Engine tests, embracing the results of over one hundred feed

Engine tests, embracing the results of over one hundred feed
JOHN LANGTON
From the
ESTATE OF JOHN LANGTON
to tke
UNIVERSITY OF
1920
TORONTO
^^;^i^%ei^-i^
ENG-INE TESTS
EMBRACING THE RESULTS OF OVER ONE HUNDRED
FEED-WATER TESTS AND OTHER INVESTIGATIONS ON VARIOUS KINDS OF STEAM
ENGINES, CONDUCTED BY
THE AUTHOR,
BY
Geo. H. Baerus, S.B.
MEMBER OF AMERICAN SOCIETY OF MECHANICAL ENGINEERS, BOSTON
SOCIETY OF CIVIL ENGINEERS, NEW ENGLAND
WATER-WORKS ASSOCIATION.
D.
NEW YORK:
VAN NOSTRAND COMPANY
1900
Copyright,
1900,
by
GEO. H. BAKRUS.
JAN
1
8 1967
;
PREFACE.
The
favor with which the author's book on "Boiler Tests,"
published in 1891, has been received, has led him to collect in
similar form the data and results
engine
tests.
Some
of
many
obtained on
of
his
the tables of results have appeared
from time to time in mechanical journals and in pamphlets
also in the Transactions of the
Engineers, but a large part
It is believed
is
American Society
now
of
printed for the
that the data liere
Mechanical
first
time.
presented will prove of
value to the engineering profession, to owners and intending
purchasers of steam plants, and to any
special
who
are interested in
The book should be
the economical production of power.
value to engineers advising intending purchasers
engines, on account of the assistance
it
will render in
GEO.
3
of
making
a wise selection.
95 Milk Strkkt, Boston, March, 1900.
of
H. BAltliUS.
COjSTTEI^TS.
PART
I.
PAGE
9
Introduction
How
THE Feed-Water Tests were conducted
12
Measurement of the Feed-Water
13
18
Indicating
General Method of Carrying on the Feed-Water Test
Leakage Tests of Valves and Pistons
....
21
23
Calibration of Instruments
28
Manner of Working up the Tests
30
m
Table
QQ
o\)
of
13750
111.
e. p.
PART
II.
Feei>-Water Tests of Simple Engines
Feei>-Water Tests of Compound Engines
Feed-Water Tests of Triple Expansion Engines
43
131
235
MMARY OF Feed-Water Tests
Review of Feei>-Water Tests
Cylinder Condensation and Leakage
I.
IL Effect of Pressure on the Economy
Effect of Speed upon Economy
III.
245
Si
IV.
V.
VL
249
251
258
259
Economy of Condensing
Effect of Superheating
Relative Economy of Simple, Compound, and Triple Ex-
....
VIII.
IX.
EcoxoMV OF Steam-jacketing and Re-heating
Engines
Effect of Ratio of Cylinder Areas
Miscellaneous
265
207
pansion Engines
VII.
261
in
Compound
270
in
Compound Engines,
273
274
Valve Setting
279
Steam-Pipe Diagrams
321
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PART
I.
ENGINE
TESTS.
INTRODUCTION.
The
first
work
in the line of engine-testing with
which the
author was intimately connected was carried out at the Massachusetts Institute of Technology in the years 1875 to 1878.
During
ments
this
time he was engaged in conducting the experi-
George B. Dixwell on the use of superheated
The experiments consisted princi-
of the late
steam for motive power.
.
pally in investigations on a Corliss engine operated with both
saturated and superheated steam
;
and they embraced the deter-
mination of the perfonnance of the engine running under both
of these conditions with different points of cut-off,
and with
different degrees of superheating, together with the determination of the effect of other
The engine
tion.
connected with
it,
in
changes in the conditions of opera-
question,
and the
formed the nucleus
testing
apparatus
of a mechanical labora-
and it
which have been
tory used in instructing the students of the Institute
was the
first
of the
many steam
laboratories
established in the colleges of this country.
these investigations a board of
experts,
;
In the course of
consisting of
Chief
Engineers Loring, Baker, and Farmer of the United States
Navy, was appointed by the Bureau of Steam Engineering to
examine the subject; and they conducted a series of tests on
the same plant, and reported them to the Bureau.
These trials
were under the active charge of the author.
this
work was such
reliable apparatus
preparing for
it
The character
as to require from the very first the
of
most
and the best methods and instruments.
In
and carrying it on, the author had the best
;
ENGINE
10
TESTS.
opportunity that could be afforded at that time for becoming
educated in the practice of engine-testing, and the training
thus acquired laid the foundation for much of the testing-work
in
which he has since been engaged.
This volume relates mainly to the engine tests which the
author has conducted subsequent to the investigations in superheating just referred
It has
to.
gaged upon any work relating
been his custom, whenever en-
to the
to advocate the determination of their
performance of engines,
economy on
the
l)asis of
feed-water consum})tion, rather than on that of the coal con-
Whenever
sumed.
advocated the feed-water
showing
water
upon simply
called
of the diagram.
test has thus l)een
By
wise been omitted.
the calls which have
test,
for indicating, he has
rather than to rely solely on the
In a great
many
undertaken where
instances the feed-
it
would have
other-
following this practice, and answering
come
in the ordinary course, the author
has personally obtained a consideral^le amoinit of
datti,
which
he believes to be of value to the engineering public, as well as
who
power or development of
economical engines, and therefore worthy of publication in
permanent form, as here presented.
The author's work in engine-testing has embraced tlie indito all
cating
of
are interested in the use of
engines
indicating for the
foi*
the
simple
purpose of valve-setting
determination of the horse-power, or for
determining the power used by various machines or depart-
ments
of
machinery which the engine drives
upon the econom}^
;
investigations
of different systems of operating engines
;
feed-water tests having for an object the improvement of the
engine and the attaininent of greater economy
in
and tests having
view the determination of the fulfilment or non-fulfilment of
;
the terms of a contract guaranteeing a certain efficiency.
These
have been made on a great variety of
engines, from the simple non-condensing engine with a single
investigations
and
tests
cylinder, to the triple expansion condensing engine
relate to
many
designs and to products of
many
;
and they
buildei-s.
They
have also covered widely varying conditions of service as to
boiler pressure, cut-off, load, speed, and valve-setting, together
11
INTRODUCTION.
with various conditions in regard to quality of steam, use of
jackets,
The
and the tightness
of valves
tests reported in this
and
pistons.
volume have not been made with
an organized attempt to obtain the jjerformance of certain types
and makes
of engines
;
but they are the result of the investigar
tions which the author has made in responding to the
whether
his clients,
it
calls of
hap[)ened to be for one object or another,
and whatever the class of engine or conditions of service. So
far as given here they are confined mainly to stationary engines
most cases
located in manufacturing establishments, and in
operating Avith a fairly uniform load.
to engines
which have a capacity
and they run from
The
first
taking up
up
volume
this size
part of the
to
is
Nearly
all
the tests apply
100 horse-power,
of at least
1700 horse-power.
devoted to Feed-Water Tests,
the simple engine, both condensing and nonand afterwards compound, and triple-expansion
engines.
The results of the test on each engine are given in a
table by itself, and they are presented in such detail that all
first
condensing,
necessary information regarding the subject
connection with the results
is
is
at hand.
In
given in each case the dimensions
and such information regarding the design of the engine, the
conditions under which it was worked, and the character of the
test, as
is
needed for a clear understanding of each case
comments on
In
all
in a
and
the engines the condition of the valves and pistons as to
leakage
t^rms.
;
the results are added where these are required.
is
pointed out so far as this can be expressed in general
The engines
few cases
selected were, as a rule, fairly tight; but
tests of leaking
engines are introduced, either on
account of the general interest attaching to them, or to show
the wasteful effect of the leakage itself in
The
some special instance.
by a chapter which
showing in brief the
tables of feed-water tests are followed
presents a general review of the results,
main points
of
information which the tests bring out.
This
chapter takes up the question of cylinder condensation, and
analyzes the tests here reported, with the object of determining
what
the percentage of cylinder condensation under different
conditions of running practically amounts
to.
The
relative
ENGINE
12
economy
of simple,
TESTS.
compound, and triple-expansion engines
is
considered, also the effects of superheating, jacketing, and piston
speed, so far as the tests furnish data on these subjects.
The chapters on Feed-Water Tests
are followed
by one de-
voted to Valve-Setting and Effects produced by various conditions of operation, as illustrated
by diagrams which the author
has taken in his professional work.
to
The
chapter relates
final
Steam-Pipe Diagrams.
In
connection with
whether feed-water
the
matter relating
tests, valve-setting, or
to
each
engine,
otherwise, sample in-
dicator diagrams are presented, usually reproduced three-fourths
size,
showing, so far as possible, average conditions.
In the
case of feed-water tests, diagrams are given from both ends of
the cylinders
;
but in cases of valve-setting and miscellaneous
diagrams, the diagrams shown are, as a rule, from only one end
of the cylinder.
HOW THE FEED-WATER
WERE
TESTS
CONDUCTED.
Before presenting the individual feed-water
review of the same as noted,
it is
of
and the
proper to give a description of
the methods employed in conducting them.
is
tests,
This description
a general character, applying rather to the usual prac-
tice of the
author in conducting these and other engine tests
than to each individual
trial
reported here.
The
principles,
ever, are applicable to the individual tests quite as
much
howas to
In the form thus presented, not only are
methods employed in conducting these tests described, but
methods which should be adopted in the general work of test^
ing, so far as they accord with the author's experience.
The two essential quantities to be determined in conducting a
feed-water test are the weight of feed-water consumed, and the
the tests as a whole.
the
indicated horse-power developed in the cylinder.
HOW THE THE
TESTS WERE CONDUCTED.
13
MEASUREMENT OF THE FEED-WATER.
How
the feed-water should be measured
depends somewhat upon the arrangement
is
a matter which
and the
of the plant
type of apparatus used for feeding the boilers, and this must in
a great
many
cases be adapted to the local conditions.
It is
always best to weigh the water, and for this purpose to erect
There are instances,
tanks and scales suitable for the work.
however, where
it is
impossible to do this, because
some head so
the weighing-tank, which
elevated
above the
pump and
;
A
size
water
may
meter
.can be
as to
is
employed
be supplied through an
orifice of
known
the system of measurement by weighing can be employed
ence to
it
can be done, the method
all others.
is to
lbs.
of
of this kind,
and an ordinary
having
water per hour, consists of a
small hogshead connected to the suction-pipe of the
injector,
and
;
be followed in prefer-
The simplest apparatus
a capacity of say 6,000
hand
at
in such
In most cases, however,
arranged so as to be calibrated.
wherever
fill
several feet
there are cases where no water
under the necessary head.
cases, or the
generally
is
neces-
is
it
sary that water should be available under
pump
mounted on platform
oil-barrel
or
scales,
the latter being supported by the hogshead on one side and by
a suitable staging on the other side.
The
barrel is filled
by
means of a cold-water pipe leading from the source of supply,
and this should be 1^" pipe for pressures not less than 25 lbs.
The
outlet valve of the barrel
is
attached to the side close to
the bottom, and this should be at least 2^" in diameter for quick
emptying.
Where
larger quantities of water are required, the
barrel can be replaced
by a hogshead, and two additional hogs-
heads can be coupled together for the lower reservoir.
capacity reached by this arrangement
when
The
the weighing hogs-
supplied through a 2^' valve under 25 lbs. pressure,
and emptied through a 5" valve, is 15,000 lbs. of water per
head
hour.
is
For
still
larger capacity
it is
desirable to use rectangular
tanks made for the purpose, and have the weighing-tank arranged
so that the ends overhang the scales
and the reservoir below,
the outlet valve, consisting of a flap valve, covering an opening
ENGINE TESTS
14
in the
With
bottom 6" or 8" square.
system can be employed for any
ordinarily
Where
met
rectangular tanks this
of
size
stationary engine
with.
is
used for measurement care should be
observed that water
is
fed through
instrument should
be
a meter
it
respect like those of the
at a uniform rate,
under conditions
calibrated
One method
test.
and the
in
every
of calibrating a
meter, which the author has found simple and fairly satisfac-
on the outlet side with a valve
and provide, at a point between this valve
and the meter, a tee with a branch having a flexible hose
A gauge is also connected to show the pressure.
attached.
tory, is to arrange the piping
known
to be tight,
The valve leading
the main line
need not be of the
to the hose
charges the water against a pressure
ing pressure, and,
no pressure.
if
the quantity
The hose
stationed to manipulate this
calibration, the stop valve in
is
tus for feeding
is
at the
quantity of supply.
much
less
than the work-
small, against practically
two empty
barrels located,
where the water can be
dis-
;
opened and so adjusted as
to
keep
The pump or other appara-
the pressure at the working point.
same time adjusted
working-
to give the
This will be determined by timing the
When
readings of the meter for, say, one minute.
rate has been secured, the
is
of
and there two workmen are
end of the line. In making the
the main is closed, and the branch
charged without doing harm
valve leading to the hose
is
carried to
is
preferably, outside of the building,
signal
full size
for under the conditions of the calibration it dis-
;
meter
is
read
;
the proper
and at that instant a
given to throw the hose into one of the barrels, the
water during the preliminary ojjerations having run to waste.
When
the first barrel
the second one
men
;
the hose
is
quickly thrown into
and while the second barrel
tip the first
second barrel
is filled,
is filling,
one over bodily and empty
is filled,
the hose
is
it.
the work-
When
the
quickly transferred back to
and immediately the second barrel is tipped over and
emptied.
This can be carried on as long as desired, depending
upon the size of the meter and the thoroughness required. The
the
last
first,
reading of the meter
is
taken when the
last barrel
becomes
HOW THE
filled,
TESTS
WERE CONDUCTED.
accurate count having been
made
of the
15
whole number.
Subsequently the quantity of water contained in the two barrels is ascertained
by weighing, and the rating
meter
of the
is
quickly determined by calculation.
When
urement
an engine
with a surface condenser, the meas-
is fitted
of the feed-water
can be somewhat simplified by
lecting the water discharged by the air-pump.
same kind
of apparatus can be used for
col-
In this case the
weighing
tanks are reversed, the water being discharged
;
but the two
first
into the
and subsequently drawn into the weighing-tank, which
is placed below it, and, after being measured, thrown away.
An approximate determination of the feed-water consumption can be made by water-glass measurement, assuming that
the type of boiler is such that this method is applicable.
The
feed-water is shut off from the boilers for a half hour's time, or
such period as is permissible, and the rate observed at which
the water disappears in the gauge glasses.
Subsequently the
volume consumed in the observed time is computed from the
known dimensions of the space occupied, and from this
the weight of the water which has been evaporated.
If the
any
water line is effected to
extent by the condition of the fires,
it is necessary in making these measurements to observe great
care that the conditions of the fires are the same at the end of
such a trial as at the beginning. In some boilers the increased
reservoir,
activity of the fire causes the water line to rise, while the dead-
ening of the
fire
open, and the
there
is
has the opposite
fire
barred
great activity of the
and new coal applied, there
fire
is,
With the damper wide
an open or free condition,
while with the damper closed
effect.
up and
;
in
for the time being, a very
The
reduction in the intensity of the heat.
damper and
the thickness and general characteristics of the
should be the same at one time as at the other.
fire
It is best to
cases, even when there
produced by these changes in the fire.
observe this precaution in
sible effect
marked
position of the
all
is
no sen-
It is also
necessary that the gauge glass and the connections leading from
the water
column
to the boiler should
be
clear; a
condition
which can be secured by blowing them out a short time (say
;
ENGINE
16
one hour) previous to the
a noticeable effect
TESTS.
When
trial.
these are
obstructed
produced upon the height of water shown
is
in the glass.
It is also necessary to be assured of the tightness of the feed
valves and check valves concerned, that none of the water
measured escapes by leakage.
The author has, in some instances, been able to obtain a
measurement of the feed-water by drawing it from the tank
which is often provided in mills for fire purposes and other
emergencies, and which
is
not regularly in use.
being generally of uniform cross-section, the water
is
subject to accurate measurement.
for measuring feed-water^
that the water
is
it is
This tank
it
contains
When such means
is
used
absolutely necessary to be assured
not in the meantime used elsewhere than for
the test, and that the valves connected with the system of regular
supply do not leak.
The
orifice
method
measurement
of
has found useful in a number of cases.
is
one which the author
One
instance
is
that of
a 1000 horse-power compound condensing engine, in which the
water from the hot well was used in the customary manner for
A test was required to determine the coal consunq>
feeding.
tion of the plant per indicated horse-power per hour, under as
The quantity of feed-water
nearly as possible working practice.
must be obtained Avithout changing,
any more than necessary, the working conditions. The hot
well overflow pipe was too near the level of the suction pipe of
used was desired
the
pump
;
but
it
to permit of using the ordinary process of
consequently, resort was had to orifice measurement.
weighing
The
feed-
tank was supplied from the overflow of the hot well through a
4-in.
pipe.
The elbow on
replaced by a
the other looked up.
this
pipe, next to the tank,
one branch of which looked
4-in. tee,
To
was
down and
the lower branch a pair of flanges
which was secured a horizontal plate having a
and this served as the orifice. The j^late
was horizontal, and the discharge from it was therefore directly
was attached,
in
hole l|-in. diameter
downward
;
into the tank.
tained a stand-pipe 3
ft.
The upper branch
high
;
and to
this pipe
of the tee con-
was attached a
HOW THE
TESTS
WERE CONDUCTED.
17
glass for showing the height of the water inside, the
graduated in inches measured from the face of the
A
same being
orifice plate.
valve in the 4-in. supply-pipe served to regulate the height of
water in the stand-pipe, and consequently the amount passing
through the
orifice.
During the progress
was maintained
of water in the stand-pipe
of
head
at such a point as to
and a careful record
Subsethe height indicated in the gauge glass.
supply the required quantity of water
was kept
of the test, the
;
the pump was stopped, the orifice was calibrated
by observing the quantity of water Avhich flowed into the tank
when
quently,
under conditions
of the average head, the contents being pre-
viously known.
Whatever method
pursued in determining the quantity of
is
water pumped into the boilers on a feed-water
made
nation should be
test,
a determi-
of the leakage of the boilers, stop valves,
safety valves, steam-pipe joints, blow-off cocks, etc., concerned
in the plant, so as to correct for such leakage,
and charge the
engine with only that quantity of feed- water which actually
passes into
it
as
steam through the throttle valve.
plish this object a leakage trial should be
after the
engine
is
shut
down
at
To accom-
made immediately
the close of the test, the
pressure being maintained in the boilers at a point nearly,
if
not quite, as high as the working pressure, and no change made
in the stop valves, etc., concerned, or in
avenues of escape.
the drips or other
Observations should then be made of the
height of water in the gauge glasses, taking readings at intervals of ten minutes for a period of one hour, or until successive
differences in the ten-minute periods
By
leakage.
show
a uniform rate of
calculating the weight of water corresponding to
the volume lost, as found by this test, which can be done
know-
ing the dimensions of the boilers, the desired correction for
leakage
is
determined.
To make
this test reliable it is neces-
sary, of course, that the throttle valve at the engine should be
tight.
The
tightness of the throttle valve can readily be deter-
mined by observing whether steam blows from the open indicator-cock of the cylinder when the steam valve is wide open,
this observation being made at the end of the cylinder which is
ENGINE
18
taking steam.
If it leaks,
the throttle valve,
it
is
and
which condenses
In some cases
valve.
may be such
may be a
leakage
it
pitches toward
also necessary that allowance be
for the steam
tions
allowance should be made for this
If there is considerable piping,
leakage.
throttle
TESTS.
and
in the pipes
it
made
collects at the
will be seen that the condi-
that the determination of the correction for
difficult
matter; but
it
is
a subject which
ought always to receive attention when the object of the test,
as in the present instances, is to determine the quantity of
steam used by the engine alone.
Whatever method
is
of feed-water
measurement
employed,
is
it
necessary that the height of water in the gauge glass should
be the same at the end of the allotted time of the test as at the
beginning.
It is
important also that the condition of the
fire
should be the same at one time as at the other, because, as
may be more or less
For example, if the test begins just before firing and
with the damper closed, or nearly closed, it should also end
just before firing and with the damper likewise closed.
It is
elsewhere noted, the height of the water
affected.
better to overrun the allotted time or even to cut
have these conditions
to
make
right,
short,
and
the duration of the trial a predetermined numl)er of
hours to the exact minute.
end
it
than to overlook them in the desire
of the test is different
If the
height of the water at the
from what
it
was
at the beginning,
the necessary correction estimated from the corresponding vol-
ume
of
water
is
applied to the quantity weighed.
This correc-
determined with sufficient accuracy, in most cases, by
calculation from the known exterior measurements of the boiler.
tion
is
INDICATLNG.
It is
unnecessary for the purposes of this volume to go into
a description of steam-engine indicators, for the books on the
subject of the indicator furnish an ample
amount
tion of this character.
say that for most of
It will suffice to
of informa-
the tests here reported the instruments used were either of the
Tabor or the Crosby pattern, or both. The methods of applying the instruments, however, the means of driving them and
HOW THE
manner
TESTS
of using them, also the
WERE CONDUCTED.
19
methods employed in calibrating
the springs, require notice.
In nearly
types of
form
all
the indicator
slow-speed
of pantagraph,
form known as the
work on the
engines,
and
Corliss,
and similar
the driving-rig has been some
in the large majority of cases, that
" lazy-tongs,"
operated from the cross-head.
The
working horizontally and
fixed
end
of the lazy-tongs
has generally been applied to one of two wooden posts, attached
to a base-board,
which in turn
is
fastened to the
second post, suitably located with reference to the
floor.
The
first, is
used
and both posts are securely
by means of three wooden braces fastened to
This method of attaching the lazy-tongs has the
the floor.
advantage of rigidity, which is so essential to a correctly driven
indicator; and the use of the carrier-pulley enables the drivingfor the support of a carrier-pulley,
fixed in position
cord to be always led
oft'
in a line parallel to the direction of
motion of the cross-head, whatever the position of the
indi-
cators with reference to the cord-pin of the lazy-tongs.
The
construction of a stand for supporting the lazy-tongs in this
manner may be considered crude and clumsy for permanent
use but the author has often found permanent rigs defective
from improper design or insecurity, due to gradual wear, and
substituted the one described.
Being made throughout of
wood, it is a device which can be quickly put together, even
where there is no carpenter-shop at hand and little material.
As it is built in such form as to easily and positively accomplish the desired ends, it has been found most useful.
For a driving-cord, a strong braided linen fish-line having an
unbraided core is used, extending a little beyond the carrierpulley and from this point to the indicators, pieces of annealed
;
;
brass wire are used, about No. 25
B.W.G. (^\"
in diameter).
For a single cylinder two cords are thus brought into use leadinitial point.
In the case of tandem cylinders, either four independent cords are used, or two independent
cords, each having branch loops at appropriate points for connecting to the two instruments.
In some cases the cords have
l)een displaced by a light wooden rod driven by the cord pin of
ing from the same
ENGINE
20
the lazy-tongs, and
TESTS.
moving on guides attached
the direction of motion being parallel to
it.
to the cylinder,
A
screw fastened
to the rod at the proper place serves to carry the
motion to the
The use of the rod in place of
cord attached to the indicator.
is especially applicable to tandem engines.
For high-speed engines the driving apparatus is some form
lever and sector, the shaft on which the lever is mounted
the cords
of
being in
many
of the engine.
In some engines of the high-speed compound
class the driving
to the
main
by a stand bolted to the frame
cases supported
motion
shaft, the
is
derived from an eccentric fastened
motion being carried from
this point to
the cylinder through a connecting-rod and bell-crank lever.
these cases an independent motion
It
is
In
used for each cylinder.
has been the custom in making these tests to employ two
indicators for each cylinder, attached as close as possible to the
end of the cylinder, using the half-inch connection, a right-angle
elbow, and the indicator-cock furnished with the instrument.
Sometimes a straight-way valve is placed below the indicatorfacility in moving the same without shutting down
the engine.
The objections to long pipes connected by a threecock for
way cock
in the center, consist in the increased friction of the
steam in passing through the greater length of the pipe
number
Avith
and in the collection of water
in the long horizontal cavity which is thus brought into play.
If two indicators are not available for an engine test, it seems
better to use one instrument, and transfer it from one end to
the other, than to employ the three-way cock and have the
the increased
of bends,
instrument fixed at the central point with the long connections.
On many
of these tests " prepared " indicator paper has
been
used, the instrument being fitted with metallic marking-points.
These marking-points are made of brass wire of suitable size,
which is reduced in diameter near the marking end to about
so that by the use of a small hand-vise, such as watchmakers employ, and an oil-stone, the marking-point is readily
kept in shape for tracing fine lines. The use of metallic paper
5^5",
is
much
sheets
to be preferred, as a
matter of convenience, to plain
with the ordinary lead-pencil point, inasmuch as
the
;
HOW THE
TESTS WERE CONDUCTED.
much
sharpening of the metal point requires
21
the less atten-
tion.
The driving mechanism
no case been any form
for the
work
referred to here has in
of reducing-wheel.
GENERAL METHOD OF CARRY1:NG ON THE
FEED-WATER TEST.
The
testing apparatus being in readiness,
working with the desired
gauge glasses
is
and the engine
the height of water in the
load,
observed, the time taken, and the position of
weighing apparatus observed.
weighed.
At the expiration of
the water in the reservoir of the
Thereafter
all
the water fed
is
the time determined upon, the water in the gauge glasses and
brought to the starting-point, and the
During
the progress of the test indicator
exact time observed.
diagrams are taken every thirty minutes, and sometimes every
twenty minutes, and at the same time the gauges are observed
and the number of revolutions per minute counted. If the
in the lower reservoir
steam
and
or
is
is
superheated, the temperature of the steam
made
Where
at convenient intervals.
required, the atmospheric pressure
tion of a barometer at
For
test.
is
observed
calorimeter tests are made, these are either continuous
if
this, it is
upon the record
of
special accuracy is
determined by observa-
some time during the progress
sufficient for all practical
of the
purposes to rely
the United States signal service at the
When
nearest station.
is
ten hours per day, say
the test
five
is
made
in a factory
hours in the forenoon and
running
five
hours
afternoon, the record in some instances embraces the
in the
whole period from the time the engine starts until the time of
In that case the initial and final readings of the
stopping.
water glasses are taken just before the engine
after it stops.
The duration
is
starts,
and just
taken from the time the engine
working speed till the time the throttle valve is
and no further account is taken of the power devel-
attains its
closed
;
oped
while
starting.
less
than
the
engine
is
In that case, the
five
reaching
first
set of
minutes after the load
its
speed
diagrams
is
put on
after
is
;
first
taken not
and the
as-
ENGINE
22
sumption
is
made
that the
k:)ss
TESTS.
of
drips during the time the engine
steam from condensation and
is first
and attaining
starting
its working speed counterbalances the deficiency of load between the time when the speed is attained and the working-
load
In factory work, the interval of time
actually applied.
is
between the attainment
tion of the full load
is
of the
working speed and the applica-
usually less than three minutes.
In taking diagrams from an engine Avith the object of deter-
mining
its
power,
it is
not desirable to limit the diagram to a
The marking-point of the indicator should
be applied long enough to obtain four or five diagrams, corresponding to that number of successive revolutions, in order
single revolution.
that the effect which the fluctuations in the governing mechan-
ism has upon the diagrams may be provided
up
the diagrams, then, the
mean
pressure
is
for.
By
average diagram, and not for any single one.
this
method, the average power which
several times as
many diagrams
as
it
to a single revolution in each case.
met where
is
In working
obtained for the
pursuing
determined relates to
would
if
it
were confined
Instances are frequently
the fluctuations in the cut-off for half a dozen suc-
cessive diagrams varies from 2 to 5 per cent of the length of
the stroke, and in such cases this matter
As
portance.
a convenience
in
is
of considerable im-
working up the diagrams, a
go over each one w^th a j^encil, and
diagram which represents an averthose made by the indicator, and in the subsequent
good plan
to follow is to
trace with dotted lines the
age of
calculations to use this dotted diagram.
When
a load
ex-
is
tremely fluctuating, this system should be carried further.
The
period of taking the diagram should extend over at least a full
minute, though
gram
it is
unnecessary to make
for this length of time.
it
a continuous dia-
The marking-point can be
pre-
ferably applied for three or four revolutions at the beginning
of,
say every ten seconds of a minute, and in that
way
the
record applies to some twenty revolutions spread over the full
period.
Having these diagrams now on
the
same
card,
an
average line can be dotted in by hand, using the best judgment
after
examining the appearance
their location.
of the various
diagrams and
HOW THE
TESTS
WERE CONDUCTED.
23
The same method is usefully applied in tests of electric railway engines. Indeed, except by some system of this kind, no
fair idea of the indicated horse-power can be obtained, and no
good comparison can be made between the indicated horse-power
and the electrical horse-power. In these engines it is best to
make the interval between the sets of diagrams thus obtained
not more than ten or fifteen minutes.
It
should be arranged
to give a signal every ten seconds while the operation
on, so that all the indicators
may
is
going
be worked together for the
Likewise, on the same signal
three or four revolutions desired.
corresponding readings are taken of the electrical instruments.
This is continued until the period of time covered is two or
more minutes. The diagrams being all taken on the same card,
without unhooking the indicators, the means is at hand for obtaining an average for the whole period, as before pointed out.
LEAKAGE TESTS OF VALVES AXD
The determination
PISTONS.
of the condition of an engine as to the
tightness of the valves and pistons has nothing to do with the
work
of
making a feed-water
the results.
When, however,
test, or of correctly
it
comes
ascertaining
to analyzing the results,
and ascertaining whether the engine is working with a proper
degree of economy, and if not, the reasons for the waste, it is
of the utmost importance that the matter of leakage should be
investigated.
water test
is
It is
always desirable, therefore, when a feed-
conducted, to supplement
it
by an inspection
of the
valves and pistons having this object in view.
This inspection
must be made when
The
the engine
is
at rest.
conditions
which surround the internal working parts of an engine at rest
are entirely different from those of the engine in motion, and
for this reason it is held by some that an examination of leakage under these circumstances gives little information which
can be applied to working conditions.
Those who take this
under
conditions
of
view hold that
motion the quantity of leakage is reduced, and it might happen that the leakage in motion
would be altogether insignificant, althougli very serious at rest.
The author takes the ground that the only course open in this
ENGINE
24
matter
is to
for certainly
motion.
rest, it
If
the examination when the engine is at rest,
no thorough inspection can be made when it is in
it is found that there is practically no leakage at
make
If,
however, there
say that there
is
is
leakage at
rest,
tight in
certainly
a probability of leakage in motion, although
not be possible to judge of
The leakage
is,
is
we can
seems reasonable to conclude that the engine
motion.
may
TESTS.
it
degree.
its
tests here referred to are
not quantitative
that
;
they do not determine the exact amount of leakage, but
rather the fact as to whether leakage does or does not exist.
They
are intended simply to give the observer a fair idea as to
the general condition of the engine.
Turning
to the
methods employed
steam-valves are readily disposed
in testing for leakage, the
In a Corliss engine,
of.
it is
necessary simply to close the two admission valves, open the
two indicator-cocks, and with the starting-bar move the exhaust
valves first one way and then the other, the throttle valve being open, and a full pressure of steam being admitted into the
When
chest.
the starting-bar
is
moved
so as to close the ex-
haust valve at the head of the cylinder, any leakage of steam
through the steam valve at that end will be made to escape at
Likewise when
the indicator-cock, and thus become visible.
the starting-bar
is
moved
so as to close the exhaust valve at the
crank end, the steam which leaks through the crank-end admission valve will show
these
movements
of
the
itself at
the open cock.
starting-bar, care
is
In making
taken that the
The quantity of leakage is
judged by the force of the current of steam blowing out of the
steam valves are held unhooked.
cock.
If the valves are tight there is
or an entire absence of vapor.
If
simply a breath of steam,
they leak badly, the cur-
rent will blow out of the indicator-cock with
noise,
and
rise to a
height of several
much
force
and
feet.
In testing the exhaust valves and pistons for leakage, the
best method is to block the fly-wheel in such a position that the
engine
is
taking steam with the piston at a short distance from
the end of the stroke, open the throttle valve, and observe
blows through.
It
is
well to try this
if
what
possible with
the
HOW THE
TESTS WERE CONDUCTED.
piston at different points.
25
the end of the exhaust pipe
If
is
open to view, as would be the case with a non-condensing
engine, the steam which leaks through can be observed at the
open
This can also be done in the case of a condensing
outlet.
engine where there
Where
is
a branch exhaust pipe leading to the at-
is condensing, and no such branch
no other opening in the exhaust pipe
in front of the condenser, a pretty good idea can be obtained of
the general facts by observing the amount which the condenser
mosphere.
the engine
is
provided, and there
is
heated by the steam which leaks.
With
is
the piston in any given position in a Corliss engine,
the leakage on such tests embraces the leakage of one exhaust
valve, one steam valve,
and the
To
piston.
investigate the
leakage of the other steam valve and the other exhaust valve,
the test
must be made with
the piston taking steam on the
In either case,
opposite stroke.
the two steam valves shows
if
them
the previous inspection of
to be leaking, this fact
must
be considered in drawing conclusions as to the leakage of the
piston and exhaust valves.
There is another method of testing the leakage of piston and
exhaust valves, namely, the " time method." The fly-wheel is
blocked, as before, with the piston at some distance from the
beginning of the stroke, the throttle valve
is
is
opened, and steam
admitted at full pressure until the cylinder
warmed.
time
is
Then
the throttle valve
observed which
is
is
shut,
is
thoroughly
and the length
of
required for the steam to escape
through the leaking openings.
an indicator
is
To conduct
the test properly,
attached to the cylinder at the end containing
the steam, and a
mark
say, one-quarter of a
is
made on
a blank card at intervals
minute from the time the throttle valve
of,
is
and by this means the rate of fall of pressure and escape
of steam is recorded.
This test, like the others, is qualitative,
and not quantitative. The relative condition of the engine
determined from results of the time tests must be judged by
closed
;
comparing with other cases where known conditions of excelIn a leaking engine the fall of pressure on a
If the leakage is serious, the
test of this kind is very rapid.
lence prevailed.
ENGINE
26
first
TESTS.
show a
down to
observation, after a quarter minute interval, might
reduction of pressure covering nearly the whole range
On
the atmosphere.
the contrary,
the engine
if
is
tight, the
reduction of pressure to the atmosphere would require from
five to ten
of one
finds that the pressure
per cent at the expiration
fifty
if
is fairly tight.
on leakage
the piston
is
more than
minute from the time of shutting the throttle valve,
the engine
If,
The author
minutes time.
will not fall as a rule
tests
with the blocked engine,
and the two valves
leak,
it is
found that
whichever stroke the piston
occupying, the piston leakage can be eliminated by discon-
necting the valve rods in such a
way
When
valves and close both exhaust valves.
resulting leakage which
is
open both steam
as to
this is done, the
observed applies to the exhaust
valves alone.
The leakage
of a piston
can always be inspected by removing
the cylinder head and applying a pressure behind the piston.
The leakage then appears
On
open end of the cylinder.
at the
large engines the operation of taking off a cylinder
head
is
The methods which have
attended with considerable labor.
been described can be brought into use with great
and
facility
save this labor, to say nothing of saving time.
The blocking
of the engine
which these
tests require
is
a
thing which should not be undertaken in any careless manner.
In most cases the masonry foundation of the engine
so
is
arranged that a piece of timber can be placed between the
spokes of the wheel, and the two ends laid upon or against the
foundation, the strain of a spoke being brought to bear upon
the middle of the timber.
say, a
12
in. or
14
in.
This timber should be of ample
stick of hard pine for an engine of
size,
1000
horse-power, the points of support at the two ends being not
over 8
ft.
apart.
The
position of the
arm should be brought
nearly as possible to the proper point before the block
duced, the leeway being
the engine, but
wedges.
filled in
as
is intro-
not by subsequently moving
by the introduction
of
wooden
filling-pieces
and
In the case of an engine having a shaft with two
cranks and a solid bed beneath each one, the engine can be
HOW THE
TESTS
WERE CONDUCTED.
27
readily blocked in certain positions by standing a piece of tim-
ber endwise, reaching from the end of the crank to the floor
number
or bed, or by putting in a
and building up
of
wooden blocks
laid flat,
Here, again, the crank-
to the desired height.
pin should be brought to the required position before the blocks
are put in,
and
filling-pieces
leeway, rather than
move
should be applied to make up the
the engine and run the risk of injury
by bringing up solid against the blocks.
Leakage tests of the valve in the case
of single-valve engines
cannot be made as satisfactorily as those in four-valve engines,
for if the valve leaks excessively it is difficult to locate by these
methods the exact place of the leak. The best that can be
done is to place the valve on its center covering both ports,
and try it under a full steam pressure. The same course can
be followed in testing the piston as that described for the four-
valve engines.
In a leaking engine of this type,
it
is
usually
necessary to test the piston with the cylinder head removed
before the investigation
is
complete.
It is needless to call attention, in
more than a passing way,
which is single-acting.
to the test of piston leakage in an engine
In a Westinghouse engine, for example, the leakage of the
is revealed by simply swinging off the cover of the crank
and observing at once what escapes from the periphery
piston
case,
of
the piston, the engine being blocked
and steam pressure
admitted into the cylinder.
The foregoing remarks on
the subject of leakage apply to
compound engines the work is
For example, in testing the leakage
of the high-pressure exhaust valves and piston, the escape of
steam is observed by opening the indicator-cock on the end of
simple engines.
to
some extent
In the case of
simplified.
the low-pressure cylinder which
ing what blows through.
is
taking steam, and observ-
Again, in testing the low-pressure
exhaust valves and piston by the time method, steam is admitted into the receiver until the desired pressure is reached,
then, after the cylinder has been thoroughly
supply shut
off,
the drop in pressure
is
receiver gauge and keeping a record of this.
is
warmed, and the
observed by reading the
A
similar course
followed in testing the leakage of triple-expansion engines.
ENGINE
28
TESTS.
CALIBRATION OF INSTRUMENTS.
For a satisfactory comparison of the steam-pipe gauge with
the initial pressure shown by the diagram, the best plan is to
compare the gauge and the indicator without changing them
from their working positions. This can be done at the same
time that the leakage tests are in progress,
when
testing the piston
for example,
as,
and exhaust valves, the fly-wheel being
blocked, and the throttle valve and admission valve set wide
By
open.
taking the reading of the steam gauge and that of
same time (the
the indicator at the
latter being
done by open-
ing the indicator-cock, then drawing a short line on the blank
card which has been applied for the purpose), not only will the
gauge
error of the
duced by the head
such error
itself
of
be allowed
but also the error pro-
This comparison alone
exists.
lish the difference in pressure
(or in the boiler to which
initial
for,
water contained in the gauge pipe,
is sufficient
if
any
to estab-
between that in the main pipe
the gauge
is
attached) and the
pressure in the cylinder of the working-engine, whether
the gauge, or indicator, or both, are in themselves correct or in
The gauge is then calibrated by reference to a standard,
and the accuracy of the indicator is established at the particular
error.
pressure used.
This single calibration
is
considered in
many
cases sufficient for determining the correct scale of the indicator
in question.
The most
method of determining the correctness
remove it from its place, and attach it to a
dead weight testing-apparatus, of the form sold by the steamgauge manufacturers, in which the pressure is produced by
satisfactory
of the gauge, is to
sealed weights resting
known
area,
through the medium of
this
its
method and the
extreme
oil
the top of a vertical plunger of
being
gauge
transmitted
or glycerine.
to
the
ahead of
Having made
it
of
in its
all
other systems for
the calibration, the indica-
working position must be corrected for
if any exists,
the head of water in the supply-pipe of the gauge,
whether
gauge
The convenience
portability of the apparatus, together with
reliability, place it
calibrating gauges.
tion of the
upon
pressure
the
be to increase the indication or to reduce
it.
HOW THE
The
calibration of
TESTS WERE CONDUCTED.
29
indicator springs used on the tests
tlie
reported in this volume has in
many
cases been carried on by
them under the action of dead weights, and correcting
the result thus found by a percentage of allowance for the
reduced tension caused by the heat of the steam in which they
testing
The
ordinarily work.
author's testing-apparatus consists of a
scale-beam mounted on knife edges, on one end of which the
The movement
weights are suspended.
other end
is
of the
beam
at the
transmitted upward by means of a vertical adjust-
able rod extending to the under side of the indicator piston.
The
tests
made with
are
the highest pressure to which
the
down to the atmosThe apparatus is operated so as
to get an average reading, whether the pressure is going up or
going down. This is done each time by pushing the scale-beam
springs are subjected, and from this point
phere at uniform reductions.
down
as far as
will go,
it
and drawing a
card, then, without changing
upward
as far as
will go,
it
the
line
on the indicator-
weight, pushing the same
and marking another
mean
line.
When
two is selected as the
The springs are in some cases compared under
the lines are measured, the
true indication.
of the
different pressures with a correct steam gauge, admitting the
steam directly into the indicator, and subjecting
it
as near as
working conditions of temperature. In making
calibrations under steam, difficulties are often experienced in
obtaining satisfactory indications, owing to the friction of the
possible to its
piston of the indicator under the action of the continuously
This
applied pressure.
is
overcome, provided the pressure
is
maintained at a constant point, by drawing two lines with the
when
instrument, one
finger as far as
pushed up as
it
far as
is pushed down with the
and the second when the arm is
the pencil-arm
will go,
it
will go, the true indication then being
taken as the mean of the two.
When
a set of indicator springs
has once been calibrated, and their exact scales obtained, the
much more
and for showing
the changes in the scale which may take place under continued
dead-weight apparatus above referred to furnishes a
satisfactory
means
use, than the
for future determinations,
steam-testing apparatus, for the reason of
its
ENGINE
30
TESTS.
greater simplicity and ease of operation, together with
dom from
its free-
the particular errors noted.
In calibrating the springs for pressures below the atmosphere,
the dead-weight apparatus referred to
resort has been
had in these
gauge, or with a standard
is
necessary to obtain a
pump
For
is
not applicable, and
comparison with a mercury
vacuum gauge,
the former being pre-
In making these comparisons in the shop or laboratory
ferred.
it
tests to
or exhauster,
this reason the
and
vacuum by
the use of some form of
proves an inconvenience.
this often
author has been in the habit of making
them in the engine room where the indicators are being used,
and where a vacuum is obtained by connecting the testingapparatus with the condenser.
paratus
the connection
is
to
All that
required for ap-
is
condenser,
the
a tee
the
for
attachment of the indicator-cock, and a mercury gauge applied
to one
end of the
down
tee.
With
this
apparatus the spring can be
which it is subjected.
It is desirable to make the calibration of an indicator spring
that is used for pressures below the atmosphere under conditions of vacuum as well as under conditions of pressure; for the
calibrated
to the lowest pressure to
fact that the spring is correct
it
is
when
a pressure
assurance that
it is
is
when subjected
applied to
it,
to compression, as
furnishes no positive
correct under tension, as
it is
when
it
is
subjected to a vacuum.
It is
of
should be
no
little
importance that the scale of the spring
known within
reasonable limits of error; for upon
knowledge depends the whole accuracy of the indicator
work, and consequently of all the results of the tests depending
upon it.
this
MANNER OF WORKING UP THE
The
results of the feed-water tests are
TESTS.
computed from the
hourly consumption of feed-water corrected for the leakage of
the boilers, pipes, and connections, as explained, and the indi-
cated horse-power developed.
the indicator"
is
The
" steam accounted for
by
determined from measurements of the dia-
grams and computations based thereon.
HOW THE
The
TESTS
WERE CONDUCTED.
31
indicator cards relating to the tests reported here have,
been measured by a polar planimeter.
as a rule,
The average
obtained by going over the line of the diagram at least twice
is
the reading taken.
The mean
scale of
effective pressure is
determined by dividing the
spring by the length of the diagram expressed
and decimals of an inch, and multiplying the quo-
the
in inches
The length of the diaby the area in square inches.
is
nearly
constant,
is
found
by selecting, say three
grams, which
sets out of every ten taken on the test, and obtaining the
average length from those three. The horse-power is computed
tient
by multiplying the "horse-power constant" for the cylinder
under consideration by the speed in revolutions per minute, and
by the mean effective pressure. The horse-power constant is
the power developed in the cylinder, assuming one pound mean
effective pressure and a speed of one revolution per minute.
It is obtained by multiplying the mean of the areas of the two
sides of the piston in square inches by twice the length of the
stroke in feet, and dividing the product by 33,000.
The mean
effective pressure used is the mean of the two measurements
obtained at the two ends of the cylinder.
In the detail tables,
giving the data and the results of the tests here reported, the
horse-power constant for each cylinder is given and the figures
of indicated horse-power in any case are the result of multipli;
cation of this constant, the revolutions given per minute, and
the
mean
pressure.
For example, in the case
which has a single cylinder 23" diameter,
effective
Engine No.
1,
stroke, with one
constant
lbs.
is
piston-rod
of
5'
3i'' in diameter, the horse-power
.1247, the speed 74.7 r.p.m., and the m.e.p. 33.08
The indicated horse-power,
viz.,
305.2,
is
the product of
these three quantities.
The water per indicated horse-power per hour is found by
simply dividing the hourly consumption of water by the indiIn the example referred to, the hourly consumption being 8477 lbs., the feed-water per I.H.P. per hour is
8477 divided by 305.2 equals 27.77 lbs.
cated horse-power.
The method
of determining the quantity of
steam " accounted
ENGINE
32
for
TESTS.
consists in measuring the diagrams for
by the indicator "
the necessary data, and using the formula
1^1^
m.e.p.
which " m.e.p."
in
is
r(c
Lv
the
+ e)^
mean
the diagrams as pointed out
Wx -
+
(h
V
e)
^
Wh]J
effective pressure
measured from
" c " the proportion of the forward
;
stroke completed either at cut-off or release, according as the
determination
made
is
at one point or another
;
"
h"
the pro-
portion of the return stroke uncompleted at compression
the proportion of the clearance space
cubic foot
"
Wh
of
" the
"
;
Wx "
" e "
;
the weight of one
steam at the cut-off or release pressure
;
and
weight of one cubic foot of steam at the compres-
sion pressure.
The
points on the diagram where these measurements are
taken are illustrated in the sample diagram Fig. 1 given below.
These points are located as follows The point of cut-off is
marked at the beginning of the expansion line after the steam
It is at the point where the curve
valve has completely closed.
changes its direction from that due to the gradually closing
:
steam valve to that of the expansion
marked
lease is
at the
end
The point
line.
of re-
expansion line just before
of the
the curve begins to drop, due to the opening of the exhaust
Likewise the compression point
valve.
ning of the true compression
is
fixed at the begin-
line, or at the
end of the curve
formed by the gradually closing exhaust valve.
followed
is
account for
The
principle
to locate the points of cut-off and release so as to
all
the steam present in the cylinder at the instant
and for all the expanded steam
present just before the exhaust valve opens.
The compression
steam valve
the
point
is
is
closed,
located with the idea of obtaining a measurement of
the exhaust steam which
all
moment
In
off
all
the exhaust valve
is
is
retained in the cylinder at the
closed.
these tests the computations are
point and the release point.
cause there
quantities
;
is
made both
It is desirable to
at the cut-
do
this, be-
often a considerable difference between the
and where there
is
such a difference,
two
much more can
HOW THE
TESTS WERE CONDUCTED.
33
be learned from the examination of the steam accounted for at
cut-off
the
than that accounted for at release.
work done during expansion
ference in the steam
is
The
difference in
not proportional to the
dif-
accounted for; and, consequently, the
economy due to cylinder condensation and leakage is more closely measured by the percentage which is
accounted for at cut-off than by the percentage accounted for
at release.
Between the two, if only one computation is to be
actual loss of
made,
it is
better to use the cut-off point than the release point.
Fig.
The
tire
proportions
"c" and "h"
length of the diagram,
1.
are found
first
by measuring the en-
erecting perpendiculars at the
extreme points, and then measuring the length up to the point
marked, dividing one by the other, and ascertaining the resulting proportion expressed in a decimal.
the
clearance
may
The proportion "e"
be found either by measurement of
for
the
clearance spaces from drawings of the cylinder and valves or
from actual test. The latter is to be preferred for drawings,
however correct in themselves, do not show the exact measurements of the material, especially of the ports and passages
which are in the state of rough casting.
To measure the clearance by actual test, the engine is carefully
set on the centre, with the piston at the end where the measurement is to be taken. Assuming, for example, a Corliss engine,
;
the best
method
to have
access to
remove the steam-valve so as
the whole steam-port, and then fill up the
to pursue is to
ENGINE
34
TESTS.
clearance space with water which
through a funnel.
The water is
poured into the open port
drawn from a receptacle containis
ing a sufficient quantity, and this has previously been measured.
When
the
whole space, including the port, is completely filled,
is measured, and the difference shows the
the quantity left
amount that has been poured in. The measurement can be
most easily made by weighing the water, and the corresponding
volume determined by calculation. The proportion required in
the formula is the volume in cubic inches thus found, divided
by the volume of the piston displacement, also in cubic inches,
and the result expressed as a decimal.
The only difficulty which arises in measuring the clearance
in this way is that occurring when the exhaust valve and
piston are not tight, so that, as the water
away and
is
poured
in, it flows
no satisfactory
measurement can be made, and it is better to depend upon the
volume calculated from the drawing. If not too serious, however, an allowance can be made by carefully observing the
length of time consumed in pouring in the water then, after
is
lost.
If
the leakage
is
serious,
;
a portion of the water has leaked out,
fill
up
the space again,
taking the time and measuring the quantity thus added, deter-
mining
in this
way
the rate at which the leakage occurs.
Data
will thus be obtained for the desired correction.
In the tests here reported the clearance has not, as a rule,
been determined by actual measurement in the manner noted,
nor even in
all
cases by the calculation
cases where the proportion of clearance
tion
is
based on the
known
from the drawing. In
assumed, the assump-
is
clearance of similar classes of engines,
determined either by water measurement or calculation.
The
which a small error in the clearance may have upon the
result of the computation of steam accounted for is not of a
effect
is a case where the cut-off is very short.
For example, if the steam accounted for with a clearance of five
per cent comes out jVir of the feed- water consumption, the result with a clearance of 4 % would be yV^, changing the proportion about j§^ at cut-off and much less at Telense.
In compound and other multiple expansion engines the same
serious nature, unless it
HOW THE
WERE CONDUCTED.
TESTS
35
formula for determining the steam accounted for by the indicator is used as that given above, but it must be adapted to the
The only change required
type of engine.
in the formula is
Here the quantity used when
in the mean
determining the steam accounted for in any given cylinder is
effective pressure.
the
collective
assumed
mean
pressure
effective
to be referred to the
cf
the
is
sum
mean
of the
In the
compound engine
case of the high-pressure cylinder of a
quantity to be used
cylinders
the
all
one under consideration.
the
H. P.
effective of the
cylinder and a quantity representing the m.e.p. of the low-pressure cylinder referred to the high-pressure cylinder
mean
by the
volume
ratio of the
If the ratio is
cylinder.
cylinder
is
that
is,
the
to be multiplied
1,
the m.e.p. of the low-pressure
by four
to determine the quantity
steam accounted for in the low-pressure cylinder
mean
effective pressure in that cylinder,
of the L. P. cylinder to the
instance given
it
4.
sum
effective pressure to be
;
of
effec-
of the
In the
effective in the
H. P.
In a triple expansion engine the mean
used for computing the steam accounted
for in the L. P. cylinder is the
sure of that cylinder
the
H. P. cylinder.
would be the mean
cylinder divided by
is
and the mean
H. P. cylinder divided by the ratio
tive pressure in the
volume
H. P.
of the L. P. cylinder to the
4 to
Likewise the quantity to be used for computing the
desired.
the
;
effective pressure in the low-pressure cylinder multiplied
sum
of the
that of the m.
e. p.
mean
of the
effective pres-
H. P. cylinder
divided by the ratio of volume of the L. P. cylinder to that of
the H. P. cylinder,
and the m.e.p.
of the intermediate cylinder
divided by the ratio of the volume of the L. P. cylinder to that
of the intermediate cylinder.
Likewise the quantity to be used
for the intermediate cylinder is the
sum
of
three quantities,
namely, the m.e.p. of the intermediate cylinder, the m.e.p. of
by the
volume of the
intermediate cylinder to that of the H. P. cylinder, and the
m.e.p. of the L. P. cylinder multiplied by the ratio of the volume
the H. P. cylinder divided
ratio of the
of the L. P. cylinder to that of the intermediate cylinder.
As an example of the proper method
mean effective pressure referred
alent
of
computing the equiv-
to either cylinder of
a
ENGINE
36
compound
engine,
which the
ratio of
the
mean
9.28
we may take the case of Engine No. 32, in
volumes of the cylinders is as 1 to 3.43, and
pressure in the two cylinders 41.26 lbs. and
effective
lbs.
TESTS.
The equivalent
respectively.
m.e.p. to be used in
computing the steam accounted for in the H. P. cylinder is
46.26 + (9.28 x 3.43) = 41.26 4- 31.83 = 73.09. For the low41.26
'
pressure cylinder the quantity
is
9.28
X
,,
=
9.28
-f-
12.03
= 21.31.
As an example of
we may take
engine
ratios of
this
method applied
to a triple
expansion
the case of Engine No. 59, in which the
volumes are as 1
and the mean effecand 10.16 lbs. respectively.
the H. P. cylinder is 60.56 +
to 2.94 to 6.5,
tive pressures, 60.56 lbs., 13.22 lbs.,
The quantity to be used for
(13.22 X 2.94) + (10.16 x 6.05) = 60.56 + 38.87 + 66.04 =
165.47.
The quantity for the intermediate cylinder is 13.22 lbs.
For the low-pressure cylinder the quantity
-1^
)
+
^
The weights
of
=
9.32
+5.98+
10.16
=
is
10.16
+
(13.22 x
25.46.
steam per cubic foot used in the formulae for
determining the steam accounted for in the tests under con-
deduced from Regnault's experiments as
given in D. K. Clark's Manual.
The following examples will serve to illustrate the use of
sideration are those
the formulae, one case being a single expansion engine and the
other a triple expansion.
Engine No. 22, Simple Condensing Engine.
Clearance
2
Cut-off pressure above zero
Weight per cubic
foot at cut-off pressure
Release pressure
Weight per cubic foot
Mean
.1773
15.5
at release pressure
effective pressure
Compression pressure
Weight per cubic foot
%
75.6
.0399
37.17
3
at compression pressure
.0085
lbs.
"
"
"
"
"
*'
HOW THE
TESTS
WERE CONDUCTED.
37
Proportion of direct stroke completed at cut-off
.172
.903
Ditto at release
Proportion of return stroke uncompleted at compression
The steam accounted
X .1773
=
-
for at cut-off
is
.
—37.17
^
.048
.
.
+ .02)^
(.172
f
'-^
+ .02) x .0085] = 369.9 x (.03404 - .00056)
= 12.39. The steam accounted for at release
(.903 + .02) X .0399 - (.048 + .02) x .0085 =
(.048
369.9 X .03348
-^^^^^^
is
[
369.9 (.03682
-
.00056)
Engine No.
=
369.9 x .03626
59— Triple
H. P. Cylinder
=
13.41.
Expansion.
at Cut-off.
Clearance
2.5
Cut-off pressure
Weight per cubic foot
at cut-off pressure
I
46.8
Weight per cubic foot at compression pressure
.1129
effective pressure
M. E. P.
lbs
.3277
.
Compression pressure
Mean
%
145.2
60.56
of all the cylinders, referred to
H. P. cylinder
.
.
.
165.47
Proportion of direct stroke completed at cut-off
.346
Proportion of return stroke uncompleted at compression
1
The steam accounted
for at cut-off
is
^
.
=
.006
.
T'^ft
L
.
165.47
X .3277 - (.006 + .025) x .1129]
83.1 X .1181 = 9.81.
.
83.1
[ (".346
^^
x (.1216
+
-
.025)
"^
.0035)
=
Intermediate Cylinder at Cut-off.
Clearance
2.5
Cut-off pressure
%
38.7
Weight per cubic foot at cut-off pressure
.0945
Mean
effective pressure
M. E.
P. of all the cylinders, referred to the intermediate cylinder,
.
•
Compression pressure
Weight per cubic foot at compression pressure
Proportion of stroke completed at cut-off
Proportion of return stroke uncompleted at compression
'^
56.28
"
20.7
'*
.406
.
.
"
13.22
.0524
.
lbs.
.008
'*
ENGINE
38
The steam accounted
.025) X .0945
.0017)
=
-
(.008
244.3 X .039
TESTS.
for at cut-off
+
=
is,
=
.025) x .0524]
x
~
I
[
(.406
244.3 x (.0407
+
-
9.53.
L. P. Cylinder at Cut-off.
Clearance
2.5
Cut-off pressure
Weight per cubic foot
Mean
at cut-off pressure
10.16
of all the cylinders, referred to L. P. cylinder
Compression pressure
Weight per cubic foot at compression pressure
Proportion of stroke completed at cut-off
Proportion of return stroke uncompleted at compression
1
The steam accounted
X .0411
-
It is
for at cut-off
(.025 X .0066)
540.1 X .01553
=
lbs.
.0411
effective pressure
M. E. P.
%
16.0
]
=
is,
^
.
.
.
25.46
2.3
.0066
.357
...
1^0
J
[
540.1 x (.0157
(.857
-
+
.025)
.00017)
=
8.39.
unnecessary to give the computations for the release
points of these diagrams, the
method being
example given above for Engine No.
The following
table
illustrated in the
22.
gives the quantity
—
^
for
mean
running from 10 to 100, advancing by twotenths of a pound and from 100 to 200 advancing by pounds.
effective pressures
;
HOW THE
TESTS WERE CONDUCTED.
39
13750
Table of
M. E.P.
13750
M.E. P.
M. E. P.
10.0
1375.0
20.0
.2
1348.
1322.1
.2
A
.6
.8
11.0
.2
.4
.6
.8
12.0
.2
.4
.6
.8
13.0
.2
.4
.6
.8
14.0
.2
.4
.6
.8
15.0
.2
.4
.6
.8
16.0
.2
.4
.6
.8
17.0
.2
.4
.6
.8
18.0
.2
.4
.6
.8
19.0
.2
.4
.6
.8
1297.1
1273.1
1253.
1227.7
1206.1
1185.4
1165.3
1145.8
1127.1
1108.9
1091.3
1074,2
1057.7
1041.7
1026.1
1011.
996.4
982.1
968.3
954.9
941.8
929.0
916.7
904.6
892.9
881.4
870.2
859.4
848.8
838.4
828.3
818.4
808.8
799.4
790.2
781.2
772.5
763.9
755.5
747.3
739.2
731.4
723.7
716.1
708.8
701.5
694.4
.4
.6
.8
21.0
.2
.4
.6
.8
22.0
.2
.4
.6
.8
23.0
.2
.4
.6
.8
24.0
.2
.4
.6
.8
25.0
13750
M. E. P.
687.5
680.7
674.0
667.5
661.1
654.8
648.6
642.5
636.6
630.7
625.0
619.4
613.8
608.4
603.1
597.8
592.7
587.6
582.6
577.7
572.9
568.2
563.5
558.9
554.4
550.
.6
545.6
541.3
537.1
532.9
528.8
524.8
520.8
516.9
.8
513.
.2
.4
.6
.8
26.0
.2
.4
27.0
.2
.4
.6
.8
28.0
.2
.4
.6
.8
29.0
.2
.4
.6
.8
509.2
505.5
501.8
498.2
494.6
491.1
487.6
484.2
480.8
477.4
474.1
470.9
467.7
464.5
461.4
M. E. P.
M. E. P.
30.0
.2
.4
.6
.8
31.0
.2
.4
.6
.8
32.0
13750
M.E.
M.E.
P.
458.3
455.3
452.3
449.3
446.4
443.5
440.7
437.9
435.1
432.4
429.7
40.0
.2
.4
.6
.8
41.0
.2
.4
.6
.8
42.0
.2
427.
.4
.4
424.4
421.8
419.2
416.7
414.1
411.7
.6
409 2
.6
.8
406.8
404.4
44.0
.6
8
33.0
.2
34.0
.2
402.
.4
399.7
397.4
395.1
392.8
390.6
388.4
386.2
384.1
381.9
379.8
377.7
375.7
373.6
371.6
369.6
367.6
365.7
363.7
361.8
359.9
358.1
356.2
354.4
352.6
350.8
349.0
347.2
345.5
.6
.8
35.0
.2
.4
.6
.8
36.0
.2
.4
.6
.8
37.0
.2
.4
.6
.8
38.0
.2
.4
.6
.8
39.0
.2
.4
.6
.8
.2
.4
.6
.8
43.0
.2
.4
.8
.2
.4
.6
.8
45.0
.2
.4
.6
.8
46.0
.2
.4
.6
.8
47.0
.2
.4
.6
.8
48.0
.2
.4
.6
.8
49.0
.2
.4
.6
.8
13750
p.
M.E.
p.
343.8
342.0
340.3
338.7
337.
335.3
333.7
332.1
330.5
328.9
327.4
325.8
324.3
322.8
321.3
319.8
318.3
315.8
315.4
313.9
312.5
311.1
309.7
308.3
306.9
305.6
304.2
302.9
301.5
300.2
298.9
297.6
296.3
295.0
293.8
292.5
291.3
290.0
288.8
287.6
286.4
285.2
284.1
282.9
281.7
280.6
279.4
278.3
277.2
276.1
ENGINE
40
TESTS.
13750
{Continu^,
Table of
JxL. Ml. Jr.
M. E.P.
13750
M.E.
M.E.
P.
.4
275.0
273.9
272.8
271.7
270.6
269.6
268.5
267.5
266.4
265.4
264.4
263.4
262.4
261.4
260.4
259.4
258.4
257.5
256.5
255.5
254.6
253.6
252.7
.6
2518
.6
.8
250.9
250.0
249.1
248.2
247.3
246.4
245.5
244.6
243.8
242.9
242.1
241.2
240.4
239.5
238.7
237.8
237.0
236.2
235.4
234.6
233.8
.8
50.0
.2
A
.6
.8
51.0
.2
A
.6
.8
52.0
.2
A
.6
.8
53.0
.2
.4
.6
.8
54.0
.2
55.0
.2
.4
.6
.8
56.0
.2
.4
.6
.8
57.0
.2
.4
.6
.8
58.0
.2
.4
.6
.8
59.0
.2
.4
.6
.8
233
232.2
231.4
230.7
229.9
60.0
.2
.4
.6
.8
61.0
.2
.4
.6
.8
62.0
.2
.4
.6
.8
63.0
.2
.4
.6
.8
64.0
.2
.4
65.0
.2
.4
.6
.8
66.0
.2
.4
.6
.8
67.0
.2
.4
.6
.8
68.0
.2
.4
.6
.8
69.0
.2
.4
.6
.8
13750
p.
M. E.P.
229.2
228.4
227.6
226.9
226.1
225.4
224.7
223.9
223.2
222.5
221.8
221.1
220.3
219.6
218.9
218.2
217.6
216.9
216.2
215.5
214.8
214.2
213.5
212.8
212.2
211.5
210.9
210.2
209.6
208.9
208.3
207.7
207.1
206.4
205.8
205.2
204.6
204.0
203.4
202.8
202.2
201.6
201.0
200.4
199.8
199.3
198.7
198.1
197.6
197.0
M.E.
70.0
.2
.4
.6
.8
71.0
.2
.4
.6
.8
72.0
.2
.4
.6
.8
73.0
.2
.4
.6
.8
74.0
.2
.4
.6
.8
75.0
.2
.4
.6
.8
76.0
.2
.4
.6
.8
77.0
.2
.4
.6
.8
78.0
•2
.4
.6
.8
79.0
.2
.4
.6
.8
13750
p.
M.E.
P.
196.4
195.9
195.3
194.7
194.2
193.6
193.1
192.5
192.0
191.5
191.0
190.4
189.9
189.4
188.9
188.3
187.8
187.3
186.8
186.3
185.8
185.3
184.8
184.3
183 8
183.3
182.8
182.3
181.9
181.4
180.9
180.4
180.0
179.5
179.0
178.6
178.1
177.6
177.2
176.7
176.3
175.8
175.4
174.9
174.5
174.1
173.6
173.2
172.7
172.3
M. E.P.
13750
M.E.
P.
.4
171.9
171.4
171.0
170.6
170.2
169.7
169.3
168.9
168.5
168.1
167.7
167.2
166.9
166.4
166.1
165.6
165.3
164.8
164.5
164.1
163.7
163.3
162.9
162.5
162.1
161.7
161.4
161.0
.6
lt)0.6
.8
160.2
159.9
169.6
169.1
158.7
158.4
158.0
157.7
157.3
157.0
156.6
156.2
155.9
156.6
155.2
154.8
154.5
154.1
153.8
153.5
153.1
80.0
.2
.4
.6
.8
81.0
.2
.4
.6
.8
82.0
.2
.4
.6
.8
83.0
.2
.4
.6
.8
84.0
.2
.4
.6
.8
85.0
.2
86.0
.2
.4
.6
.8
87.0
.2
.4
.0
.8
88.0
.2
.4
.6
.8
89.0
.2
.4
.6
.8
HOW THE
TESTS
WERE CONDUCTED.
41
13750
Table of
M. E.P,
90.0
.2
A
.6
.8
91.0
.2
.3
.6
.8
92.0
.2
.4
.6
.8
93.0
.2
.4
.6
.8
94.0
13750
M.E.P.
152.8
152.4
152.1
151.7
151.4
151.1
150.8
150.5
150.1
149.8
149.5
149.2
148.8
148.5
148.2
147.9
147.5
147.2
146.9
146.6
146,3
.2
146.
.4
.6
145.6
145.3
.8
145.
95.0
.6
144.7
144.4
144.1
143.8
143.5
143.2
142.9
142.6
142.3
.8
142.
.2
.3
.6
.8
96.0
.2
.4
97.0
.2
.4
141.7
141.4
141.2
M.E.P.
97.6
.8
98.0
7
8
9
110
1
2
3
4
115
6
7
8
9
120
1
2
3
4
125
7
8
9
.4
139.7
139.4
139.1
138.9
138.6
138.3
.6
138.
6
.8
137.8
137.5
136.14
134.8
8
9
.2
4
105
6
126
140.
.8
2
3
M.E.P.
.2
99.0
1
140.9
140.6
140.3
{Concluded).
.4
.6
100
13750
M.E.P.
^
1.33.5
130
1
2
3
4
135
7
140
1
132.21
130.95
129.71
128.5
127.31
126.15
2
3
4
145
6
125.
8
9
150
123.88
122.77
121.68
120.61
119.57
118.54
117.52
116.53
115.55
114.58
113.64
112.71
111.79
110.89
110.
7
1
2
3
4
155
6
7
8
9
160
1
2
3
13750
M.E.P.
109.13
108.27
107.42
106.59
105.77
104.96
104.17
103.38
102.61
101.85
101.10
100.36
99.64
98.92
98.21
97.52
96.83
96.15
95.49
94.83
94.18
93.54
92.91
92.28
91.67
91.06
90.46
89.87
89.29
88.71
88.14
87.59
87.03
86.48
85.94
85.40
84.88
84.36
M.E.P.
164
165
6
7
8
9
170
1
2
3
4
175
6
7
8
9
180
1
2
3
4
185
6
7
8
9
190
I
2
3
4
195
6
7
8
9
200
13750
M.E.P.
83.84
83.33
82.83
82.34
81.85
81.36
80.88
80.41
79.94
79.48
79.02
78.57
78 13
77.68
77.25
76.82
76.39
75.97
75.55
75.14
74.73
74.32
73.93
73.53
73.14
72.75
72.37
71.99
71.62
71.25
70.88
70.51
70.15
69.80
69.44
69.10
68.75
PART
11.
FEED-WATEE
TESTS.
SIMPLE ENGINES.
[
These engines are
all horizontal,
unjacketed,
and of
the automatic cut-off
type, imth fly-ball governor, unless otherwise specified.]
43
:
ENGINE
No.
1.
Simple Non-Condensing.
Kind
Four-valve (Corliss)
of engine
Number of
Diameter
Diameter
1
cylinders
23
of cylinder
in.
3i
in.
Stroke of piston
5
ft.
Clearance
2^
of piston-rod
H. P. constant for
m.
1 lb.
e. p.
%
.1247
one revolution per min.
Inside diameter of steam pipe
7
in.
Inside diameter of exhaust pipe
8
in.
Condition of valves and pistons regarding leakage
Data and Besults of Feed-Water
.
Test,
.
Practically tight
.
Engine No.
1.
Ordinary
Character of steam
Duration
5.75
consumed
Feed-water consumed per hour
Pressure in steam pipe above atm
Weight
Mean
of feed-water
lbs.
lbs.
8,477
effective pressure
Revolutions per minute
72.3
lbs.
33.08
lbs.
74.7
Indicated horse-power
Feed-water consumed per
Initial pressure
hrs.
48,741
305.2
I.
H. P. per hour
H. P.
27.77
Measurements based on Sample Diagrams.
above atmosphere
lbs.
72.8
lbs.
Steam-pipe pressm-e above atmosphere
73.6
lbs.
Cut-off pressiu-e above zero
66.5
lbs.
Release pressure above zero
24.3
lbs.
Mean
33.12
lbs.
2.8
lbs.
effective pressure
Back pressure
at
mid stroke above atmosphere
Proportion of stroke completed at cut-off
Steam accounted
Steam accounted
.367
for at cut-off
23.32
lbs.
for at release
23.66
lbs.
Proportion accounted for at cut-off
.84
Proportion accounted for at release
.852
Engine No. 1
vertical boilers,
is
supplied with steam in part from a
and
in part
number
of
from a single boiler of the horizontal
The mixed steam showed no superheating, though probably commercially dry.
The valves and pistons
were all fairly tight. The load consisted of cotton machinery.
On another occasion two tests were made on this engine, the
return tubular type.
first
with ordinary steam as above, and the second with super-
heated steam, the horizontal boiler in the latter case being out
of service.
The
principal data
and results were
45
as follows
ENGINE
46
TESTS.
Test.
No.
Chabacteb of Steam.
Mean
effective pressure
Proportion of stroke completed at cut-off
Feed-water consumed per I. H P. per
hour
Steam accounted
Steam accounted
lbs.
lbs.
for at cut-off
for at release
Proportion accounted for at cut-off
Proportion accounted for at release
The marked
No.
16.
.
.
.
lbs.
.
.
.
lbs.
.
.
.
.
ic.
Superheated
Obdinary.
82°.
34.46
.375
35.07
29.34
24.6
25.26
26.83
25.42
24.15
.392
.839
.861
effect of superheating is indicated
.
.947
.900
by comparing
two tests. By superheating the steam 82 degrees the consumption of feed- water per I. H. P. per hour was reduced about
these
9 per cent.
A
feature in these results
steam accounted for by the indicator.
is
the effect
upon the
between cutoff and release from 24.6 pounds to 25.26 pounds when ordinary steam is used, whereas the contrary effect is produced
under the influence of the superheating, the quantity falling
from 25.42 pounds
It increases
to 24.15 pounds.
ENGINE
No.
1
-60
Head End
-40
-20
Crank End
-40
-20
ENGINE
No. 2,
Simple Non-Condensing.
Kind
Four-valve (Corliss)
of engine
Number
of cylinders
1
Diameter of cylinder
Diameter of piston-rod
28.5
Stroke of piston
69.5
Clearance
1 lb.
m.
e. p.
one revolution per miu.
in.
%
.1898
Inside diameter of steam pipe
8
Condition of valves and piston regarding leakage
Data and Results of Feed-Water
Test,
.
.
in.
Fairly tight.
.
Engine No.
2.
Character of steam
Ordinary
Duration
6.08
of feed-water
consumed
hr.
79,467
Feed-water consumed per hour
Pressure in steam pipe above atmosphere
Mean
in.
3
H. P. constant for
Weight
in.
4
effective pressure
lbs.
13,070
lbs.
101
lbs.
41.18
Revolutions per minute
lbs.
64.B
Indicated horse-power
Feed-water consumed per
I.
H. P. per hour
506.5
H. P.
25.8
lbs.
Measurements based on Sample Diagrams.
pressure above atmosphere
91
^bs.
Cut-off pressure above zero
82.9
lbs.
Release pressure above zero
26.3
lbs.
Mean
41.18
lbs.
4.2
lbs.
Initial
effective pressure
Back pressure
at
mid -stroke above atmosphere
Proportion of stroke completed at cut-off
Steam accounted for
Steam accounted for
.315
at cut-off
21.06
lbs.
at release
21.35
lbs.
Proportion accounted for at cut-off
.817
Proportion accounted for at release
.828
Engine No. 2
is
supplied with steam from water tube boilers.
A calorimeter test showed less than one per cent of moisture.
The steam valves and piston were tight. The exhaust valves
leaked a small amount.
The load was that of a cotton-mill.
47
ENGINE No. 2
100
-80
Head End
-60
40
20
-100
-80
60
Crank End
40
20
L-
ENGINE
No. 3.
Simple Condensing.
Kind
Four-valve (Corliss)
of engine
Number
of cylinders
2
.
Diameter of each cylinder
Diameter of piston-rod
Stroke of each piston
20i
in.
21
in.
4
ft.
Clearance
%
3
m. e.
Inside diameter of steam pipe
H. P. constant for
1 lb.
p.
one revolution per min.
.1532
Inside diameter of exhaust pipe
Condition of valves and pistons regarding leakage
Data and Results of Feed-Water
.
Tests,
.
....
Character of steam
Duration
Weight of feed-water consumed
Feed-water consumed per hour
Pressure in steam pipe above
atmosphere
Vacuum in condenser
Mean effective pressure
Revolutions per miliute
Indicated horse-power
Feed-water consumed per I H
per hour
.
.
.
.
.
Engine No.
Test
.
.
AllCondensing,
lbs.
lbs.
B.
Three Ends Condensing, One End
Non-Condensing.
Ordinary
hrs.
in.
in.
Fairly tight.
.
Test A.
COXDITION8 AS TO USE OF CONDENSEK.
8
8
Ordinary
4.75
21,185.
4.75
24,671.
6,194.
4,460.
H.P.
67.2
26.2
22.79
60.3
210.5
69.1
26.5
24.79
60.3
229.
lbs.
21.11
22.68
lbs.
in.
lbs.
Measurements based on Sample Diagrams.
Initial
pressure above atmosphere
lbs.
60.8
64.1
Average of
Three
Condensing
Ends.
Cut-off pressure above zero
Release pressure above zero
.
Mean
.
.
.
lbs.
59.9
9.3
23.23
.
.
.
lbs.
11.9
lbs.
.138
13.85
14.77
.
.
.
pressure
Back pressure at mid-stroke above
or below atmosphere
Proportion of stroke completed
tjffective
at cut-off
Steam accounted
Steam accounted
for at cut-off
for at release .
Proportion accounted for at cutoff (average for the whole
engine)
Proportion accounted for at release
.
lbs.
lbs.
lbs.
lbs.
49
NONCONDENSING
End.
63.
63.
10.5
26.41
13.5
19.01
-12.
.152
13.95
14.59
+ 1.
.185
21.19
24.06
.654
.695
.697
.748
ENGINE
50
Engine No. 3 has a pair
TESTS.
of cylinders exhausting into a jet
condenser operated by a direct^connected air-pump.
The
ex-
haust passages and piping are arranged so as to run one end of
one cylinder non-condensing.
One
test
was made running both
cylinders condensing, and one test running three ends condens-
ing and one end non-condensing.
The engine
is
supplied with
steam from horizontal return tubular boilers. The quality of
the steam was not tested, but it was probably commercially dry.
One steam
valve and the exhaust valves of one cylinder showed
some leakage.
fairly tight.
The remaining valves, and the pistons, were
The engine was employed in driving several man-
working in connection with water-wheels.
steam due to running one end of the cylinder
The gain in fuel that would
non-condensing is about 7%.
be produced by utilizing the exhaust steam from this end for
heating feed-water for the boilers, assuming that it increases
the temperature from 60 to 210 degrees, is sufficient to cover
the increased steam consumption and leave a net fuel saving of
some 7%.
ufactories
The
loss in
ENGINE
R.H.Cyl.
No. 3 a
Head End
60-
40—
20-
6040-
20-
L,H.Cyl.
Head End
ENGINE
R.H. Cyl.
No. 3 b
Head End
60-
40-
L.H.CyI.
Head End
20-
0-"
60-
40-
20-
10
L.H. Cyl.
Crank End
ENGINE
No. 4.
Simple Condensing.
Kind
Four-valve (Corliss)
of engine
Number
of cylinders
1
Diameter of cylinder
Diameter of piston-rod
34.2 ins.
4S
Stroke of piston
5
Clearance
3
H.P. Constant for one lb. m.e.p., one rev. per minute
Inside diameter of steam pipe
Inside diameter of exhaust pipe
Data and Results of Feed Water
.
Test,
.
Engine No.
ins.
ins.
4-
deg.
10.8
of feed-water
consumed
Feed-water consumed per hour
Pressure in steam pipe above atmosphere
Vacuum in condenser
hrs.
125,420
lbs.
11,613
lbs.
83
lbs.
24.8
ins.
35.58
lbs.
effective pressure
Rev. per min
53.3
Indicated horse-power
Feed-water consumed per
523.43 H. P.
I.
H. P. per hour
22.19
Measurements Based on Sample Diagrams
:
above atmosphere
Steam-pipe pressure above atmosphere
76. 1 lbs.
83
.
Cut-off pressure above zero
lielease pressure above zero
effective pressure
at mid-stroke,
Back pressure
lbs.
—
Initial pressure
Mean
6
7
Fairly tight.
.
Duration
Mean
%
Superheated 25
Character of steam
Weight
ft.
.2764
.
.
Condition of valves and piston regarding leakajge
ins.
lbs.
lbs.
.
lbs.
Head End.
NON-CONDENSING.
Crank End.
Condensing.
71.9
17.5
28.22
76.7
18.1
41.88
above or
below atmosphere
lbs.
Proportion of stroke completed at cut-off
Steam accounted for at cut-off
Steam accounted for at release
Proportion accounted for at cut-off
(average of two ends)
Proportion accounted for at release
lbs.
.
.
.
lbs.
.
.
.
lbs.
.
53
lbs.
—
+ 2.1
.237
18.79
18:75
lbs.
.7 66
lbs.
.7 7
11.7
.230
15.18
15.43
ENGINE
54
TESTS.
Engine No. 4 exhausts into a jet condenser with direct-conOne end is run condensing, and the other
nected air-pump.
The boilers are of the vertical type,
end non-condensing.
which superheat the steam. Steam was supplied for other
purposes than power, and the amount thus used was determined and allowed for. There was slight leakage of the steam
valves.
The exhaust valves and
The load was
piston were practically tight.
that of a cotton mill.
ENGINE No.4
80-
60-
Head End
40-
20-
0-
80-
60-
Crank End
40-
20-
lO-J
ENGINE
No.
5.
Simple Condensing.
Kind
of engine
Number
»
.
Four-valve (Corliss)
of cylinders
2
Diameter of each cylinder
Diameter of each piston-rod
Stroke of each piston
„
ins.
4?
ins.
4.5
Clearance
ft.
%
3
H.P. Constant for one lb. M.E.P. one rev. per min.
Inside diameter of steam-pipe
Condition of valves and pistons regarding leakage
.
Data and Results of Feed- Water
Test,
.
.4484
.
7
.
ins.
Some
.
Engine No.
leakage.
5.
Character of steam
Duration
Ordinary
5.55
consumed
Feed-water consumed per hour
Weight
82.5
of feed -water
lbs.
18,063
lbs.
Pressure in steam pipe
71.1
Vacuum in condenser
Mean effective pressure
26.2
32.41
Revolutions per minute
lbs.
in.
lbs.
47.3
Indicated horse-power
Feed-water consumed per
hrs.
100,253
I.
H. P. per hour
687.39 H. P.
......
26.28
lbs.
Measurements Based on Sample Diagrams.
COXDENSIKG
CVLINDER.
Initial pressure
above atmosphere
Cut-off pressure above zero
.
lbs.
.
....
....
lbs.
Release pressure above zero
Mean effective pressure
Back pressure at mid-stroke, above or be
lbs.
lbs.
low atmosphere
lbs.
Proportion of stroke completed at cut-off
Steam accounted for at cut-off
Steam accounted for at releasq
Proportion accounted for at cut-off (aver
age for whole engine)
Proportion accounted for at release
.
.
.
lbs.
.
.
.
lbs.
.
Engine No. 5 has a pair
NONcondensino
Cylinder.
70.3
63.5
20.1
39.54
65.2
63.
20.
26.2
+ 4.9
-9.4
.298
16.78
17.36
.308
24.47
25.39
.784
,813
.
of cylinders,
one of which exhausts
into a jet condenser, with direct-connected air-pump,
other
is
non-condensing.
Steam
56
is
and the
furnished from cylinder
ENGINE
56
TESTS.
and it appeared to be commercially dry.
A small
amount was used for other purposes than running the engine,
but the quantity thus consumed was determined, and allowThe valves and piston of one cylinder
ance made for it.
showed some leakage those of the other cylinder were fairly
tight.
The load consisted of cotton machinery.
boilers,
;
ENGINE No. 5
R.H.Cyl.
Head End
L.H. Cyl.
Head End
60-
40-
20-
O-J
-60
L.H.Cyl. Crank End
.40
-20
ENGINE
No. 6.
Simple Condensing.
Kind
of engine
Number
Four-valve (Corliss)
of cylinders
2
...
Diameter of each cylinder
Diameter of each piston rod
Stroke of each piston
.
,
.
26i
in.
3f
in.
5
Clearance
H. P. Constant for one
lb.
m.
e. p.
one rev. per minute,
%
.3254
Inside diameter of steam pipe
8
Inside diameter of exhaust pipe
Condition of valves and pistons regarding leakage
Data and Results of Feed-Water
Test,
.
.
.
Engine No.
in.
10
in.
Some
leakage.
6.
Character of steam
Ordinary
Duration
Weight
ft.
3
5.08
of feed-water
consumed
Feed-water consumed per hour
hrs.
71,150
lbs.
14,006
lbs.
Pressure in steam pipe
84.4
Vacuum in condenser
Mean effective pressure
27.3
lbs.
in.
36.73
.
Revolutions per minute
lbs.
51.1
Indicated horse-power
610.74 H. P.
Feed-water consumed per
I.
H. P. per hour
22.95
lbs.
Measurements based on Sample Diagrams.
Three
Ends
COXDENSIJfO.
Initial pressure above atmosphere
Cut-off pressure above zero
Eelease pressure above zero
Mean
.
.
.
effective pressure
mid
low atmosphere
Back pressure
at
lbs.
77.3
74.6
lbs.
17.2
lbs.
39.46
lbs.
10.2
.233
15.81
15.56
lbs.
Noxcondex8ing
End.
76.
73.8
20.4
30.03
stroke, above or be-
Proportion of stroke completed at cut-off
Steam accounted for at cut-off
Steam accounted for at release
Proportion accounted for at cut-off (average for whole engine
Proportion accounted for at release (aver.
....
....
lbs.
lbs.
.271
22.12
22.63
.757
.754
age)
Engine No. 6 has a pair
+ 4.5
of cylinders exliausting into a jet
condenser with direct-connected air-pump.
58
One
cylinder was
ENGINE
No.
6.
59
run condensing, and one end of the other cylinder non-conSteam is supplied from sectional boilers with large
densing.
all appearances it was in a commercially dry
Both pistons showed some leakage, but the valves
drum, and from
condition.
were
all fairly tight.
The load consisted
of cotton machinery.
ENGINE No. 6
B.H. Cyl,
Head End
ENGINE
No.
7.
Simple Non-Condensing.
Kind
Four-valve (Corliss)
of engine
Number
of cylinders
1
Diameter of cylinder
Diameter of piston rod
26zb
in.
3h
in.
Stroke of piston
4
ft.
Clearance
3
H. P. constant for one lb. m. e. p. one revolution per min.
Inside diameter of steam pipe
Condition of valves and piston regarding leakage
.
Data and
Results of
Feed-Water
Test,
.
.
Engine No.
6
in.
Some
leakage.
7.
Character of steam
Ordinary
Duration
Weight of
5.1
feed-w^ater
consumed
Feed-water consumed per hour
Pressure in steam pipe above atmosphere
Mean
%
.1285
effective pressure
Revolutions per minute
lbs.
6,742
lbs.
80.5
lbs.
27.82
lbs.
64.7
Indicated horse-power
232.3
Feed-water consumed per
hrs.
34,386
I.
H. P. per hour
H. P.
29.03
lbs.
Measurements based on Sojnple Diagrams.
Initial pressure
above atmosphere
79.6
lbs.
76.6
lbs.
Release pressure above zero
19.6
lbs.
Mean
27.3
lbs.
5.4
lbs.
Cut-off pressure above zero
effective pressure
Back pressure
at
mid stroke above atmosphere
Proportion of stroke completed at cut-off
Steam accounted
Steam accounted
.237
for at cut-off
21.77
lbs.
for at release
23.31
lbs.
Proportion accounted for at cut-off
Proportion accounted for at release
Engine No. 7
is
.75
.803
supplied with steam from horizontal return
tubular boilers, presumably in a commercially dry condition.
The valves were fairly tight, but there was considerable leakage
The load consisted of cotton machinery.
of the piston.
61
ENGINE
No. 7
80
60-
Head End
40-
20-
80-
60-
40-
2fl-
Crank End
.
ENGINE
No.
S.
Simple Condensing.
Kind
Four-valve (Corliss)
of engine
Number
of cylinders
1
Diameter of cylinder
Diameter of piston rod
30
ins.
41
ins.
Stroke of piston
6
ft.
Clearance
3
H.P. constant for one lb. m.e.p. one rev. per min.
Condition of valves and piston regarding leakage
.
Data and Results of Feed-Water
.
.
%
.2543
Fairly tight.
Tests.
Test B.
Extra.
Superhtd. 37° Superhtd. 37°
....
....
Mean
,
Test A.
Ordinary.
C0NDIT10>fS AS TO PRESSURE.
Character of steam
Duration
Weight of feed-water consumed
Feed-water consumed per hour
Pressure in steam-pipe above atmosphere
Vacuum in condenser
.
.
hrs.
lbs.
lbs.
lbs.
ins.
effective pressure
5.667
40,281.
7,104.
53.1
29.7
lbs.
26.63
Revolutions per minute
H.P.
Indicated horse-power
lbs.
Feed-water consumed per I.H.P. per hour
366.4
19.39
54.1
5.167
34,984.
6,771.
68.2
29.8
26.3
54.1
361.8
18.71
Measurements based on Sample Diagrams.
Test A.
Ordinary.
Conditions as to Pressure.
Initial
pressure above atmosphere
.
.
.
lbs.
46.5
47.0
Cut-off pressure above zero
lbs.
Relea.se pressure above zero
effective pressure
Back pressure at mid-stroke below atm.
Proportion of stroke completed at cut-off
Steam accounted for at cut-off
Steam accounted for at release
Proportion accounted for at cut-off
lbs.
11.1
lbs.
26.84
Mean
.
....
....
.
Proportion accounted for at release
.
.
.
.
lbs.
— 12.4
lbs.
.247
lbs.
15.89
15.19
.819
.783
lbs.
Test B.
Extra.
—
,
61.5
58.6
9.8
26.39
12.4
.165
13.98
13.72
.747
.733
Engine No. 8 exhausts into a jet condenser with direct-conSteam is supplied through a 12-inch pipe,
nected air-pump.
160 feet in length, from vertical boilers which superheat. The
amount of superheating at the boilers on the test was 67 degrees.
63
64
ENGINE
TESTS.
was subsequently found that the loss of temperature between
the boilers and the throttle valve was 60 degrees so that the
steam entering the cylinder was still in a slightly superheated
The valves and pistons were fairly tight. The load
condition.
It
;
consisted of cotton machinery.
Advantage was taken of the comparatively light load to make
The other conditions
a trial of the engine under two pressures.
of running were the same in both cases.
It appears that the increase of pressure from 53 pounds to
68 pounds was attended by a reduction in the steam consumpThere is a marked
tion amounting to nearly four per cent.
increase in the cylinder condensation (and leakage), with the
shortening of the cut-off and increase of pressure.
ENGINE No. 8 a
Head End
ENGINE No. 8b
Head End
ENGINE
No. 9.
Simple Condensing.
Kind
of engine
Number
Four valve
.
of cylinders
(Corliss)
2
Diameter of eacli cylinder
Diameter of each piston rod
Stroke of each piston
30i
Clearance
Conditions as to Use of Condensek.
ft.
%
.515
.
.
.
Data and Results of Feed- Wafer
ft.
6
3
.
H.P. constant for one lb. m.e.p. one rev. per minute
Inside diameter of steam pipe
Condition of valves and pistons regarding leakage
ins.
41
8
ins.
Some
leakage.
Tests.
Test A.
Test B.
All
Con-
FOIRTHS
densing.
densing.
Tjiree-
Con-
Superlitd. 24°
Character of steam
Supd.24°
Duration
hrs.
5.1
Weight of feed-water consumed
lbs. 70,565.
P'eed-water consumed per hour
lbs. 13,838.
Pressure in steam pipe above atmo.sphere
lbs.
70.8
Vacuum in condenser
ins.
26.7
Mean effective pressure
lbs.
32.00
Revolutions per minute
46.
Indicated horse-power
H.P.
7;58.27
per
hour lbs.
Feed-water consumed per 1. H.P.
18.25
'
....
....
83,060!
15,4(57.
73.4
26.7
31.44
.
46.
758.10
20.4
Measurements based on Sample Diagrams.
NonThree
Condens- Ends
ing
CondensEnd.
ing.
Conditions as to Use of Condenser.
Initial pressure
above atmosphere
Cut-off pressure above zero
.
.
....
....
Release pressure above zero
Mean effective pressure
Back pressure at mid-stroke, above or below
atmosphere
lbs.
lbs.
lbs.
lbs.
lbs.
Proportion of stroke completed at cut-off
Steam accounted for at cut-off
Steam accounted for at release
Proportion accounted for at cut-off
Proportion accounted for at release
.
.
.
lbs.
.
.
.
lbs.
.
.
.
.
67.7
70.4
12.9
32.10
— 11.5
.185
14.97
14.52
67.8
72.5
13.9
34.54
70.7
69.6
17.2
26.11
— 11.5
-f4.0
.247
21.94
21.88
.82
.8 36
.796
.8
.202
14.45
14.47
ENGINE
No.
9.
67
Engine No. 9 has a pair of cylinders exhausting into a jet
condenser with direct-connected air-pump.
Steam is supphed
in a slightly superheated condition from vertical
boilers.
Arrangements are made so that one end of one cylinder can be
One test was made with this end operating non-condensing, and another when the whole engine was
run non-condensing.
The exhaust valves and steam valves of
The steam valves of the other
pistons of both cylinders showed some leakage.
running condensing.
one cylinder were fairly tight.
cylinder and the
The load consisted of cotton machinery.
The loss of steam due to running one end
2.15 pounds per
of one cylinder
H. P. per hour, or 11.8%
of the quantity required when running condensing.
non-condensing
is
I.
ENGINE
No. 9 a
R.H.Cyl.
Head End
ENGINE No.Qb
60-
R.H.Cyl.
Head End
40-
20-
60
R.H. Cyl.
40-
20-
lO-J
V
L.H. Cyl.
Head End
Crank End
ENGINE
No. lO.
Simple Condensing Engine.
Kind
Double Valve
of engine
Number
2
of cylinders
Diameter of each cylinder
Diameter of each piston rod
17
Stroke of each piston
24.2
in.
2,7o
Clearance
in.
in.
%
2
H. r. Constant for one lb. ni.
Inside diameter of steam pipe
one
e. p.
rev. per
minute
.
.0551 H.P.
.
in.
Some leakage
Condition of valves and pistons regarding leakage
Data and Results of Feed- Water
Tests,
COXUITIOXS AS TO USE OF COXDEXSEU.
Character of steam
Duration
Weight of ieed-water consumed
Feed-water consumed i)er hour
Pressure in steam pipe above atmosphere
Vacuum in condenser
lbs.
79.
lbs.
.
23.0
39.36
154.7
336.2
20.51
ins.
I.
hour
i)er
5.21
41,415.
7,952.
75.9
5.7
39,299.
0,895.
lbs.
lbs.
H.P.
NoxCOXDEXSIXO,
Superhtd. 16° Superhtd. 41°
Mean
I.
10.
CoxnENSIXG.
hrs.
....
....
effective pressure
Revolutions per minute
Indicated horse-power
Feed-water consumed i)er
Engine No.
H.P.
lbs.
30.82
152.9
310.1
25.64
Measure nents based on Sample Diagrams.
COXDITIOXS AS TO USE OF CoXDEXSEK.
CoXDEXSlXi
pressure above atmosphere
Steam-pipe pressure above atmosphere
Cut-off pressure above zero
Release pressure above zero
lbs.
lbs.
19.7
Mean
lbs.
42.15
lbs.
10.1
.262
lbs.
15.82
15.53
Initial
lbs.
....
lbs.
effective pressure
Back pres. at mid stroke above or below atm
Proportion of stroke completed at cut-off
Steam accounted for at cut-off
Steam accounted for at release
Proportion accounted for at cut-off
Proportion accounted for at release
.
Engine No. 10 has a
the siphon type, which
belt
pump
operated
l)y
})air
is
.
.
.
.
.
.
74.5
78
72.9
COXDEXSJXIJ
76
79
72 8
25 2
37 43
+
1
.337
20.78
20.42
.771
.7o7
of cylinders, with
.811
.
70.')
condenser of
supplied with water by means of a
the enoine.
Th.3
main valves are
bal-
ENGINE
The
slides.
of the
main value, which
is
of
the engine running condensing,
are
on a seat in the interior
box pattern.
controlled by a shaft governor.
ing.
71
10.
cut-off valve rides
anced
is
No.
One
The
test
cut-off valve
was made with
and one running non-condens-
Steam is furnished by superheating vertical boilers, Avhich
190 feet distant from the throttle valves, the connecting
pipe being 10 inches in diameter.
The
loss
of
temperature
from the boilers to the engine amounted to 54 degrees. The
pistons and cut-off valves were practically tight.
The main
The engine worked in connecvalves showed some leakage.
tion with water-wheels, and supplied power to a cotton-mill.
From these results it appears that the consumption of steam
when the engine Avas run condensing was 5.13 lbs. per I. H. P.
per hour less than when run non-condensing, or 20%.
In making this comparison it should be observed that there
was a comparatively poor vacuum, both in the cylinders and in
the condenser, which acted unfavorably upon the condensing
and this was further influenced in the same direction
by the relatively small amount of superheating.
result
;
ENGINE No.lOa
60—
R.H. Cyl.
Head End
ENGINE
No. lOb
80—1
RH.
0-1
Cyl.
Head End
ENGINE
No.
1
1.
Simple Non-Condensing Engine.
Kind
of engine
Number
Four valve
.
of cylinders
1
Diameter of cylinder
Diameter of jDiston rod
161
ins.
21
ins.
Stroke of piston
32
Clearance
ins.
%
4
H.P. constant for one lb. m, e. p. one rev. per min
Inside diameter of steam pipe
Condition of valves and piston regarding leakage
.
Data and
0346H.P.
5
.
.
in.
Considerable leakage
of Feed-Water Test.
Hefiults
Character of steam
Ordinary
Duration
5.47
Weight of feed-water consumed
Feed-water consumed per hour
hrs.
10,277
lbs.
1,879
lbs.
Pressure in steam-pipe above atmosphere
Mean effective pressure
61
lbs.
18.19
lbs.
Pevolutions per minute
79.8
Indicated horse-power
50.2
Feed-water consumed per
I.
11.
P. per
hour
I.
H.P.
37.43
lbs.
Measurements based on Sample Diagrams.
Initial pressure
above atmosphere
58.6
lbs.
Cut-olT pre .sure above zero
56.1
lbs.
Release pressure above zero
16.7
lbs.
Mean
18.29
lbs.
1.1
lbs.
effective pressure
Back pressure
at
mid stroke above atmosphere
Proportion of stroke completed at cut-off
Steam accounted
Steam accounted
.234
for at cut-off
21.52
lbs.
for at release
27.42
lbs.
Proportion accounted for at cut-off
.575
Proportion accounted for at
.732
Engine No. 11
is
relea.se
controlled by a shaft governor.
It
has
means for adjustment to take up
supplied from return tubular boilers, probably
piston valves provided Avith
wear.
in
Steam
is
The piston and one steam
The other steam valve and both exThe engine was employed in driving a
a commercially dry condition.
valve were
fairly tight.
haust valves leaked.
machine-shop.
The
effect of leakage,
low pressure, and light load is seen
shown on this test.
in
the excessive consumption of steam
74
i
ENGINE
Head End
No.
1
ENGINE
No. 12.
Simple Condensing Engine.
Kind
of engine
Number
Four valve
of cylinders
Diameter of cylinder
Diameter of piston rod
24i
in.
3i
in.
Stroke of piston
4
Clearance
3
H. P. constant for one lb. m. e.
Inside diameter of steam pipe
p.
one revolution per min.
Condition of valves and piston regarding leakage
Data and
Results of Feed-
.
.
Water
.
ft.
%
.112 H.P.
Inside diameter of exhaust pipe
6
in.
7
in.
Considerable leakage
Test.
Character of s^eam
Duration
Weight
(Corliss)
1
Ordinary
5.07
consumed
of feed -water
Feed-water consumed per houi*
Pressure in steam pipe above atmosphere
lbs.
6,01)1)
lbs.
70.2
Vacuum in condenser
Mean effective pressure
lbs.
21
in.
33.06
Revolutions per minute
lbs.
70.2
Indicated horse-power
258.2
Feed-water consumed per
hrs.
30,920
I.
H. P. per hour
I.
H.P.
23.62
lbs.
63.6
lbs.
Measurements ba^ed on Sample Diagrams.
Initial pressure
above atmosphere
Cut-off pressure above zero
56.1
lbs.
Release pressure above zero
17.8
lbs-
Mean
33.31
lbs.
8.5
lbs.
effective pressure
Back pressure
Proportion of
mid
below atmosphere
stroke completed at cut-off
at
Steam accounted for
Steam accounted for
stroke,
29
at cut-off
16.99
lbs.
at release
17.75
lbs.
Proportion accounted fcr at cut-off
719
Proportion accounted for at release
751
Engine No. 12 exhausts into a
direct connected air-pump.
The
jet
joints
condenser having
out of repair, and the condenser was rendered somewhat
cient.
Steam
is
a
about the air-pump were
ineffi-
supplied from vertical boilers, which do not
superheat, but which appeared to furnish steam in a commer-
ENGINE
cially
dry condition.
One
No.
of the
steam valves leaked, but the
remaining valves were practically
badly.
The load
77
tight.
The
piston leaked
consisted of cotton machinery.
Leakage and the poor vacuum are evidently accountable for
the comparatively low result obtained here.
ENGINE No. 12
Head End
ENGINE
No. 13.
Simple Non-Condensing Engine.
Kind
Single valve
of engine
Number
of cylinders
1
Diameter of cylinder
Diameter of piston rod
1-4.5
Stroke of piston
13
in.
2k
Clearance
in.
in.
%
10
H. P. constant for one
lb.
m.
one revolution per min.
e. p.
.
.0108 H.P.
.
Inside diameter of steam pipe
4
in.
Inside diameter of exhaust pipe
6
in.
Condition of valves and piston regarding leakage
.
Data and Results of Feed-Water
Character of steam
.
Considerable leakage
Test.
Ordinary
,
Duration
Weight
2.5
of feed-water
consumed
Feed-water consumed per hour
Pressure in steam pipe above atmosphere
Mean
hr.
4,350
lbs.
1,740
lbs.
102.5
effective pressure
lbs.
20.07
Revolutions per minute
lbs.
246
Indicated horse-power
53.2(3
Feed-water consumed per
hour
I. -H. P.. -.per
I.
32.(37
H.P.
lbs.
Measurements based on Sample Diagrams.
Initial pressure
above atmosphere
98. 1
lbs.
Cut-off pressure above zero
07.0
lbs.
Release pressure above zero
40.8
lbs.
Mean
20.07
lbs.
2.0
lbs.
effective pres.sure
Back pressure
at
mid stroke above atmo.sphere
-|-
Proportion of stroke completed at cut-off
Steam accounted for
Steam accounted for
at cut-off
.
.
.110
.
at release
Proportion accounted for at cut-off
is
of
the
lbs.
lbs.
.530
Proportion accounted for at release
Engine No. 13
17.72
22.50
.
high-speed
class,
mth
a
'^Q\
shaft
The valve
is of the piston type, unpacked.
Steam
from a water-tube boiler, and is presumed to
The piston was fairly
be in a commercially dry condition.
governor.
is
supplied
tight.
end
it
The valve
at one
leaked badly.
end was
The load
fairly tight,
consisted of a
but at the other
dynamo
furnish-
ing current for electric lighting.
The leaking of the piston valve is evidently responsible in
some degree for the comparatively poor showing on this engine.
78
ENGINE
Head End
No. 13
ENGINE
No. 14.
Simple J^on- Condensing Engine.
Kind
of engine
Number
Single valve
of cylinders
Diameter
Diameter
1
of cylinder
8.5
in.
of piston rod
If
in.
Stroke of piston
10
in.
8
%
Clearance
H. P. constant for 1 lb. m. e. p. one revolution per min.
.0028 H.P.
Inside diameter of steam pipe
in.
2h
Inside diameter of exhaust pipe
in.
Sh
Condition of valves and piston regarding leakage
Considerable leakage
.
.
.
Data and Results of Feed- Water
Test.
Character of steam
Ordinary
Duration
Weight
21
of feed-water
consumed
Feed-water consumed per hour
Pressure in steam pipe above atmosphere
Mean
hrs.
2,357
lbs.
942.8
lbs.
105.3
lbs.
30.58
effective pressure
Kevolutions per minute
lbs.
315
Indicated horse-power
27.35
Feed-water consumed per
I.
H. P. per hour
I.
H.P.
34.44
lbs.
Measurements based on Sample Diagrams.
pressure above atmosphere
Initial
99.6
lbs.
Cut-off pressure above zero
92.5
lbs.
Release pressure above zero
34.1
lbs.
Mean
30.58
lbs.
1.7
lbs.
effective pressure
Back pressure
at
mid stroke above atmosphere
Proportion of stroke completed at cut-off
Steam accounted
Steam accounted
.194
for at cut-off
17.92
lbs.
for at release
21.17
lbs.
Proportion accounted for at cut-off
62
Proportion accounted for at release
615
Engine No. 14
shaft governor.
unpacked.
is
It is
Steam
is
of the high-sj^eecl class, controlled
The valve leaked
tight.
is
supplied from a water-tube boiler, proba-
bly in a commercially dry condition.
namo
by a
provided with a piston valve which
badly.
The
piston was fairly
The load consisted
of a dy-
furnishing current for electric lighting.
The
boiler plant in this case
is
the same as that of Engine
No. 13.
The
main
inferior
economy exhibited here can
to leakage.
80
be attributed in the
ENGINE No. 14
Head End
ENGINE
No. 15.
Simple Condensing Engine.
Kind
Four valve
of engine
Number
of cylinders
Diameter of each cylinder
Diameter of each piston rod
Stroke of each piston
23
Clearance
m. e.
steam pipe
1 lb.
Inside diameter of
p.
in.
5
ft.
one revolution per min.
%
.249 H.P.
Inside diameter of exhaust pipe
Condition of valves and pistons regarding leakage
.
.
Data and Results of Feed- Water
of feed-water
6
in.
10
in.
Eairly tight
.
Test.
Character of steam
Duration
Superheated
5.63
consumed
Feed-water consumed per hour
Pressure in steam pipe above atmosphere
Vacuum in condenser
Mean
in.
3i
3
H. P. constant for
Weight
(Corliss)
2
74,247
lbs.
13,187
lbs.
77.6
lbs.
27.9
effective pressure
in.
40.49
Revolutions per minute
lbs.
61
Indicated horse-power
Feed-water consumed per
59<*
hrs.
615.1
I.
H. P. per hour
I.
H.P.
21.44
lbs.
Measurements Based on Sample Diagrams.
condensikg
Cylinder.
Initial pressure
above atmosphere
.
.
.
lbs.
Cut-off pressure above zero
lbs.
Release pressure above zero
Mean effective pressure
Back pressure at mid stroke, above or be-
lbs.
low atmosphere
lbs.
lbs.
Proportion of stroke completed at cut-off
Steam accounted for at cut-off
Steam accounted for at release
Proportion accounted for at cut-off
Proportion accounted for at release
.
....
....
.
.
.
.
.
lbs.
lbs.
73.2
80.1
23.6
36.05
+ 2.6
11.9
.264
16.62
15.93
.29^
22.41
22.29
.895
.874
Engine No. 15 has a pair of cylinders provided with a jetThe exhaust piping
arranged so as to run one cylinder condensing and the other
condenser and direct connected air-pump.
is
76.7
80.4
20.3
45.33
NONcokdensing
Cylindek.
82
ENGINE
No.
83
15.
non-condensing, as was done on the
test.
Steam
is
supplied
from vertical superheating boilers. A small quantity of steam
was drawn from the boilers and used for other purposes than
running the engine
allowance
both
made
cylinders
amount
;
but the quantity
for
is
insignificant,
The steam valves and
it.
and no
pistons of
were practically tight. There was a slight
exhaust valves. The engine was
of leakage in all the
employed
A
is
in driving a cotton-mill.
was made on this engine to determine the amount of
power used by the air-pump, which had a vertical plunger 22
The connecting-rod on the
in. diameter and 12-in. stroke.
condensing side was disconnected, and cards were taken from
the other cylinder first with air-pump in operation and then
with air-pump stopped. The load driven in both cases was
The difference in the two results
the shafting of the mill.
was 10.8 horse-power, or 1.8% of the working power of the
test
engine.
Sample indicator diagrams from the pump cylinder are apfirst taken under the working conditions, and the
second obtained on the power test.
pended, the
ENGINE
No. 15 AIR
PUMP
1-30
20
Working Conditions
HIO
O
L- 10
20
Power Test
10
10
ENGINE No.
15
RH. Cyl. Head End
i
ENGINE
No. 16.
Simple Non-Condensing Engine.
Kind
of engine
Number
Single valve
2
of cylinders
Diameter of each cylinder
Diameter of each indicator rod
Stroke of each piston
9.5
in.
375
in.
9
Clearance
in.
%
14.1
H. P. constant for
1 lb.
m.
e. p.
one revolution per min.
.
.00322 H.P.
.
Inside diameter of steam pipe
3^
in.
Inside diameter of exhaust pipe
Sh
in.
Condition of valves and pistons regarding leakage
Some
Data and Results of Feed - Water
Lettek by Which Tests aeeDesigxated
Character of steam
Duration
Weight
A.
B.
Ordinary
Ordinary
Ordinary
2.908
4,248.3
1,460.9
2.983
3,451.9
3.067
2,854.76
930.8
H.P.
91 7
39.49
352.2
44.81
92.5
30.76
353.9
35.08
22.33
356.7
25.66
lbs.
32.6
32.99
36.27
hrs.
of feed-water
consumed
lbs.
.
Feed-water consumed per hour
pipe above
atmosphere
lbs.
Mean
lbs.
.
Tests.
1,157.2
Pressure in steam
.
.
lbs.
.
effective pressure
Revolutions per minute
Indicated horse-power
Feed-water consumed per
per hour
I.
.
92.1
H
....
Measurements based on Sample Diagrams.
Letter by Which Tests are Designated
pressure above atmosphere
Initial
lbs.
Cut-off pressure above zero
Release pressure above zero
.
.
lbs.
Mean
.
.
lbs.
effective pressure
.
.
.
lbs.
Back pressure at mid stroke above
atmo.sphere
Proportion of stroke completed
lbs.
at cut-off
Steam accounted
Steam accounted
for at cut-off
for at release
Proportion accounted for at cut.
lbs.
.
lbs.
off
A.
84.7
79.1
38.3
39.57
+ 2.1
.353
22.92
23.27
B.
C.
85.3
77.1
33.8
82.7
76.4
30.6
30.55
22.29
+2.8
+4.
.278
21.61
22.89
.206
19.92
24.07
.703
.652
.549
.714
.694'
.664
Proportion accounted for at release
Engine No. 16 has a pair
with working parts inclosed
The
valve,
which
is
common
of vertical, single-acting cylinders
in a
chamber partly
filled
with
oil.
to both cylinders, is of the piston
85
ENGINE
86
Steam
type with ring packing.
TESTS.
is
supplied by a vertical boiler
having only a small amount of steam-heating surface.
At
a
point near the throttle valve a calorimeter test showed the
presence of
3%
of moisture,
in the record of results.
no allowance for which
The
is
made
pistons were practically tight.
The valve leaked a small amount. The load consisted of a
Prony brake applied to the fly-wheel.
The tests were three in number, made with different loads.
In these tests it appears that the economy of the engine was
not materially affected by reducing the load from 44.81 H. P.
to 35.08
H. P.
A
further reduction, however, increased the
consumption.
In connection with
made on
this
series
of
tests,
the effect of a reduction of speed.
experiments were
It
was found that
with a sj)eed of 201.1 revolutions per minute, the steam con-
sumption per horse power per hour was increased 10 per cent.
ENGINE No. 16a
R.H.Cyl.
ENGINE
No. 16b
ENGINE No. 16c
ENGINE
No. 17,
Simple Condensing Engine.
Kind
of engine
Number
...
Four valve
.
of cylinders
.
1
.
Diameter of each cylinder
Diameter of piston-rod
18
nis.
ins.
2|
Stroke of piston
.
.
Clearance
.
.
SO
.
5
H.P. Constant for one lb. m.e.p. one rev. per min.
Condition of valves and pistons regarding leakage
ins.
.031
H.P.
Fairly tight
.
Data and Results of Feed -Water
Tests.
NoxCONDENSING.
Conditions Regarding Use of Condenser.
Condensing.
Test.
A.
B.
Ordinary
Ordinary
Character of steam
hrs.
Duration
lbs.
Weight of feed-water consumed.
lbs.
Feed-water consmned per hour
.
Pressure in steam pipe above atmoslbs.
phere
ins.
Vacuum in condenser
lbs.
Mean effective pressure
Rev. per min
I. H.P.
Indicated horse-power
Feed-water consumed per I. H.P. per hour lbs.
.
.
.
.
4.1
19.298.
4,707.
4.
24,201.
6,050.2
67.6
67.
25.^
33.75
1«5.6
213.2
22.08
33.34
164.4
209.1
28.93
Measurements Based on Sample Diagrams.
Conditions Regarding Use op Condenser.
Condensing
Test.
NonCondensing
A.
B.
62.1
18.0
64.5
28.2
33.75
Cut-off pressure above zero
Release pressure above zero
lbs.
Mean
lbs.
lbs.
effective pressure
Back pressure
at
mid
33.99
stroke, above or
below atmosphere
lbs.
Proportion of stroke completed at cut-off
lbs.
Steam accounted for at cut-off
lbs.
Steam accounted for at release
accounted
for
at
cut-off
Proportion
(average of two ends)
Proportion accounted for at release
lbs.
.
.
.
.
.
.
—10.3
.264
17.11
17.5
.
Engine No. 17 has balanced
slide valves.
.77
.79
.385
23.75
23.54
.82
.81
The condenser
of the siphon pattern supplied with injection
is
water under a
Steam is taken from return tubular boilers, and
presumed to be commercially dry. The valves were prac-
natural head.
it is
+1.5
88
ENGINJS
tically tight,
tests
89
but the pistons showed a small amount of leakage.
The load was
Two
No. 17.
cotton machinery.
were made, one with the condenser in operation,
and the other with the engine exhausting into the atmosphere.
From
these figures
it
appears that the use of the condenser
secured a reduction in the Aveight of steam consumed amount-
ing to 24%.
This comparison
is
made under
comparatively low boiler pressure.
ENGINE No. 17a
60-
40-
Head End
20-
0—
lO
60—
40-
20-
lO-J
Crank End
conditions of a
ENGINE
No. 17b
60-
40
20-
0-"
60-
40
Crank End
20
0-J
i
ENGINE
No. 18.
Simple Condensing Engine.
Kind
of engine
Number
Four valve
of cylinders
Diameter
Diameter
(Corliss)
2
of each cylinder
.
20j ins.
,
of each piston rod
3
ins.
Stroke of each piston
4
ft.
Clearance
3.4
H.P. Constant for one lb. m.e.p., one rev. per minute
Inside diameter of steam pipe
Condition of valves and pistons regarding leakage
Data and Results of Feed -Water
Tests,
....
%
.0772
6
ins.
Tairly tight
Engine
JVb. 18.
Test.
A.
B.
Cylinders in Use.
One.
Both.
Ordinary
Ordinary
Character of steam
Duration
Weight of feed-water consumed
Feed-water consumed per hour
Pressure in steam pipe above atmosphere
Vacuum in condenser
hrs.
....
....
Mean effective pressure
Revolutions per minute
Indicated horse-power
Feed-water consumed per
lbs.
lbs.
lbs.
.
ins.
lbs.
I.
I.
H.P. per hour
H.P.
lbs.
5.867
24,310.
4,143.5
84.5
26.4
43.2
61.16
204.02
20.31
5.844
25,045.
4,285.6
59.
25.9
21.84
61.8
208.45
20.56
Measurements based on Sample Diagrams.
Test.
Cylinders in Use.
above atmosphere
Steam-pipe pressure above atmosphere
Cut-off pressure above zero
Release pressure above zero
Initial pressure
.
....
Mean
effective pressure
Back pres.
at
.
lbs.
lbs.
lbs.
lbs.
mid stroke below atmosphere
Proportion of stroke completed at cut-off
Steam accounted for at cut-off
Steam accounted for at release
Proportion accounted for at cut-off
Proportion accounted for at release
.
.
.
.
lbs.
.
lbs.
.
lbs.
.
.
.
.
B.
Both.
lbs.
.
.
A.
One.
—
82.7
85.3
89.3
18.0
42.51
11.7
.188
14.73
14.8
.725
.729
56.8
60.5
64.9
8.7
21.72
—11.9
.111
13.73
14.61
.668
.711
Engine No. 18 has a pair of cylinders with a jet condenser
Steam is furnished
by return tubular boilers, and calorimeter tests showed that the
operated by a direct connected air-pump.
91
;
ENGINE
92
TESTS.
The
percentage of moisture varied from ^ to 1 per cent.
were
steam valves
fairly
tight.
The piston and
Those
valves of one cylinder were absolutely tight.
other cylinder leaked a
trifle.
exhaust
The load consisted
of
the
of cotton
machinery.
Two tests were made, one with both cylinders in operation
and the other with a single cylinder, and -in both the load was
The tests were made with different
practically the same.
boiler pressures.
In this case
it
appears that the economy of feed-water con-
sumption was practically the same whether one cylinder was
used or the whole engine. As would be expected, however,
the proportion of steam accounted for by the indicator was the
least in the case of the earlier expansion.
In a series of experiments, of which these formed a part, a
test
was made
to determine the effect of increasing the boiler
pressure 20 lbs. above the nonnal, one cylinder being in use.
In one case the pressure was 85.8
and the mean
and
jW
and
effective pressure was, in
in both cases.
one,
lbs.,
The
round numbers, 41
cut-off occurred at
of the stroke in the other.
tion with the high pressure was 19.5
in the other 105.7
lbs.
yW
lbs.
the stroke in
of
The steam consumpper
I.
H. P.
jjer
hour,
and with the low pressure 19.2. In other words, there was a
This engine was
trifling loss due to the increase of pressure.
not absolutely tight, and doubtless leakage affected the results,
so that the advantage of the increase of pressure
was
to
some
extent counteracted.
On
the last mentioned test the steam accounted for was .67.
ENGINE No. 18a
80-
60-1
Head End
40-
20-
0lO-J
80-|
604020-
0-1
10-
Crank End
ENGINE No.
18b
r60
-40
R.H. Cyl.
Head End
20
-60
-40
R.H. Cyl. Crank End
20
—
60-
40-
L.H. Cyl.
20-
10-
Head End
ENGINE
No. 19.
Simple Condensing Engine.
Kind
Single Valve
of engine
Number
of cylinders
1
Diameter of cylinder
Diameter of piston rod
18.5
in.
2i
in.
Stroke of piston
30.
in.
Clearance
7.5
H. P. Constant for one
m.
lb.
e. p.
one rev. per minute
.
Some leakage
Condition of valves and pistons regarding leakage
Data and Results of Feed -Water
Character of steam
Test.
Ordinary
.
Duration
5.011
consumed
Feed-water consumed per hour
Weight
%
.0405 H.P.
.
of feed-water
27,838.1
,
Pressure in steam pipe above atmosphere
.
.
.......
5,555.4
hrs.
lbs.
lbs.
74.5
lbs.
Vacuum in condenser
Mean effective pressure
24.8
ins.
39.05
lbs.
Revolutions per minute
129.33
Indicated horse-power
204.59
Feed-water consumed per
I.
H. P. per hour
27.15
H. P.
lbs.
Measurements based on Sample Diagrams.
Initial pressure
above atmosphere
69.3
lbs.
Steam-pipe pressure
73.2
lbs.
Cut-off pressure above zero
66.8
lbs.
Release pressure above zero
29.0
lbs.
Mean
38.1
lbs.
effective pressure
Back pressure
at
mid
stroke,
below atmosphere
Proportion of stroke complete at cut-off
Steam accounted
Steam accounted
.... —8.9
lbs.
303
for at cut-off
19.17
lbs.
for at release
18.97
lbs.
Proportion accounted for at cut-off
Proportion accounted for at release
706
699
Engine No. 19 has a single unpacked piston valve, controlled
by a shaft governor. The engine is provided with a jet condenser operated by an independent air-pump, driven by steam.
The steam used by the condenser was determined separately.
and allowance made for it in the record. Steam is supplied by
horizontal return tubular boilers, and it is presumed that it was
The piston of the engine
was tight, but the valve placed at the middle of its throw
showed considerable leakage. The load was cotton machinery.
in a commercially dry condition.
95
ENGINE No.
Head End
19
ENGINE
No. 20.
Simple Condensing.
Kind
Four valve
of engine
Number
of cylinders
2
,
Diameter of each cylinder
Diameter of each piston rod
Stroke of each piston
28
ins.
4
ins.
5
ft.
%
3
Clearance
.3694 H.P.
H.P. constant for one lb. m.e.p. one rev. per minute
Inside diameter of steam pipe
Inside diameter of exhaust pipe
Condition of valves and pistons regarding leakage
9
ins.
10
ins.
Some leakage
Data and Results of Feed- Water
Tests.
B.
Test.
A.
Co'DiTioxs Regarding Use of Condenser.
Condensing.
CONDENSING.
Character of steam
Duration
hrs.
Weight of feed-water consumed
lbs.
Feed-water consumed per hour
.lbs.
Pressure in steam pipe above atmosphere
lbs.
Vacuum in condenser
ins.
Ordinary.
Ordinary
10.08
102,947.
9.83
133,925.
13,620.
65.1
.
....
.
.
.
.
Mean
effective pressure
Revolutions per minute
Indicated horse-power
Feed-water consumed per
lbs.
10,213.
68.1
23.
23.12
52.
I.
I.
H.P. per hour
H.P.
444.
lbs.
23.
NON-
23.81
50 5
451.6
30.16
Measurements based on Sample Diagrams.
Test.
A,
Conditions Regarding Use of Condense
pressure above atmosphere
Steam-pipe pressure
Cut-off pressure above zero
Release pressure above zero
Initial
Mean
.
.
.
mid
low atmosphere
at
lbs.
lbs.
lbs.
lbs.
.
....
....
Engine No. 20 has a pair
slide valves.
63.6
68.1
71.2
9.5
23.25
B.
NONCondensing.
62.5
65.7
70.1
16.8
23.97
stroke, above or be-
Proportion of stroke completed at cut-off
Steam accounted for at cut-off
Steam accounted for at release
Proportion accounted for at cut-off
Proportion accounted for at release.
anced
lbs.
lbs.
effective pressure
Back pressure
Condensing
.
.
.
.
lbs.
lbs.
of cylinders
It is fitted
with a
97
jet
—11.1
.119
14.13
14.37
.615
.025
+1.5
.222
21.8
23.17
.722
.766
with gridiron unbalcondenser, operated
ENGINE
98
TESTS.
The engine
by an independent air-pump driven by steam.
^Aas
supplied from horizontal return tubular boilers, and the steam
on subsequent occasions was found to contain 1.2
%
of moisture.
In the matter of leakage, the engine was in fair condition,
though every valve, and the pistons as well, showed a small
amount of leakage. The load was made up largely of rubber
grinding machinery.
Two tests were made, one with the condenser in operation,
and the other with the engine exhausting into the atmosphere,
Independent tests were made,
the condenser being stopped.
showing the quantity of steam used by the air-pump and
;
allowance has been made for
Besides
it.
used has not been allowed
tlie
engine, the boiler
The steam thus
tank-pump.
supplied the feed-pump and a
for.
The air-pump, which had a single steam cylinder 16" in diameter and 24" stroke, when making 56.3 single strokes per
minute, was found to use 1682 lbs. of steam per hour.
The
power developed amounted to 12.8 H. P. consequently the
;
air-pump consumed 131.7
On
lbs.
of
steam per
I.
H. P. per hour.
the condensing test the air-pump used over 13 per cent of
the entire quantity
The quantity
consumed by the engine.
steam used by the engine and air-pump
working condensing was about 12 % less than that used when
the engine was running non-condensing, and the quantity used
of
by the engine alone about 24
%
less.
In explanation of the comparatively low proportion of feed-
water accounted for on the condensing
test, it is
probable that
allowance made for steam used by the condenser was less than
owing
fact
that
cylinder drips were kept partially open.
On
the
test,
actual
quantity,
these were closed.
to the
ordinarily
the
the condenser
Probably the actual consumption of
feed-water was somewhat below the 23
lbs.
given in the table,
and the actual proportions referred to were somewhat higher.
It should also be noted that the portion unaccounted for includes the steam used by the boiler-feed and tank-pump on both
tests,
probably 2 or 3
%
of the whole.
ENGINE
No. 20a
R.H.Cyl.
Head End
ENGINE No. 20b
60-
40-
R.H.Cyl.
Head End
R.H.Cyl.
Crank End
20
0-1
60-
40
20-
60
UH.Cyl. Head End
40
20
-60
L.H.Cyl.
Crank End
-40
20
L-
ENGINE
No. 21.
Simple Non- Condensing Engine.
Kind
of engine
Number
Four valve
...........
of cylinders
Diameter of cylinder
Diameter of piston rod
1
...........
lU
ins.
II
ins.
Stroke of piston
20
Clearance
10
H. P. constant for one lb. m. e.
Inside diameter of steam pipe
p.
.0104 H.P.
4
.
.
Data and Results of Feed- Water
.
Test.
Superheated 4°
Duration
Weight
8
consumed
of feed-water
Feed-water consumed per hour
Pressure in steam pipe above atmosphere
Mean
in.
Considerable leakage
.
,
.
%
one revolution per min.
Condition of valves and piston regarding leakage
Character of steam
ins.
.
effective pressure
lbs.
1,292
lbs.
.
Revolutions per minute
64.5
lbs.
15.7
lbs.
198.3
Indicated horse-power
Feed-water consumed per
hrs.
10,341
»
I.
H. P. per hour
32.26
1. H.P.
40.04
lbs.
63.1
lbs.
Measurements based on Sample Diagrams.
pressure above atmosphere
Corresponding steam-pipe pressure
Initial
67
lbs.
Cut-off pressure above zero
60.4
lbs.
Release pressure above zero
22.4
lbs.
Mean
15.4
.
effective pressure
Back pressure
at
mid
stroke, above atmosphere
.......
Proportion of stroke completed at cut-off
Steam accounted
Steam accounted
2
lbs.
lbs.
238
for at cut-off
24.85
lbs.
for at release
25.13
lbs.
Proportion of feed-water accounted for at cut-off
62
Proportion of feed-water accounted for at release
627
Engine No. 21 has balanced
slide valves.
Steam
is
furnished
from a horizontal return tubular boiler of special design, which
is
provided with a considerable amount of steam-heating sur-
face.
The steam was superheated at the boiler 30°, and at a
One of the exhaust valves and the
The other steam valve and the other
were fairly tight.
point near the engine 4°.
piston
101
ENGINE
102
TESTS.
The
exhaust valve leaked very badly.
dynamo furnishing
It is
to
load consisted of a
a steady current for electric lighting.
evident that leakage of the valves referred to had
do with the poor showing.
ENGINE No.
21
8060-
Head End
40200-
80
1-60
Crank End
40
-20
-0
much
ENGINE
No. 22.
Simple Condensing Engine.
Kind
of engine
Number
Four valve
.
.
of cylinders
1
Diameter of cylinder
Diameter of piston rod
34^b
ins.
5
ins.
Stroke of piston
5
ft.
Clearance
2
.
.
.
.
,
H.P. constant for one lb. m. e. p. one rev. per min
Inside diameter of steam pipe
Inside diameter of exhaust pipe
Condition of valves and piston regarding leakage
%
2791 H. P.
14
ins.
14
ins.
Some leakage
Data and Eesults of Feed- Water
Test.
Ordinary
Character of steam
Duration
5.367
.
...
Weight of feed-water consumed
Feed-water consumed per hour
.
•
.
.
.
..........
hrs.
60,879
lbs.
11,343
lbs.
Pressure in steam-pipe
82.3
lbs.
Vacuum in condenser
Mean effective pressure
27.9
ins.
37.23
lbs.
Kevolutions per minute
59.9
Indicated horse-power
Feed-water consumed per
613.4
I.
H. P. per hour
I.
H.P.
18.49
lbs.
Measurements based on Samjde Diagrams.
Initial pressure
above atmosphere
Corresponding steam-pipe pressure
Cut-off pressure above zero
...
,
.
.
Release pressure above zero
Mean
effective pressure
Back pressure
at
.
.
.
.-
.
.
.
.
.
...-—;— 7—7
mid stroke above or below atmosphere
.
.
.
81.9
lbs.
84.2
lbs.
75.6
lbs.
15.5
lbs.
37.17
lbs.
13.6
lbs.
Proportion of stroke completed at cut-off
Steam accounted
Steam accounted
.172
for at cut-off
12.39
lbs.
for at release
13.41
lbs.
Proportion of feed-water accounted for at cut-oif
Proportion of feed-water accounted for at release
Engine No. 22 has
,669
.725
slide valves of the gridiron type.
It
is
provided with a siphon condenser, the injection water for Avhich
is
furnished under natural head.
Steam
is
supplied to the
engine from water tube boilers through a 16-inch pipe -331 feet
At a point near the engine it is drained by means
which discharges to waste. On the test 143 ll)s. of
water were discharged per hour, and no allowance has been made
in length.
of a trap,
103
ENGINE
104
for this.
At
TESTS.
a point between the trap and the engine the steam
was found by calorimeter
test to contain 2^ per cent of mois-
The exhaust valves were practically tight. The steam
valves and pistons showed some leakage.
The engine worked
ture.
in connection with a water-wheel driving cotton machinery.
In examining the results of this
test,
which
in
view
of the
long distance which the steam had to travel between the boil-
and the engine, shows excellent economy, the part which
overlooked.
This was phenominally low, the back pressure at the middle of the stroke being
only about one pound above a perfect vacuum.
ers
the
vacuum played cannot be
ENGINE No. 22
rSO
Head End
ENGINE
No. 23.
Simple yon-Condensing Engine.
Kind
of engine
Number
Single valve
of cylinders
1
Diameter of cylinder
Diameter of piston rod
8
ins.
1/b
ins.
Stroke of piston
12
ins.
Clearance
14
%
H. P. constant for 1 lb. m. e. p. one revolution per
Inside diameter of steam pipe
Inside diameter of exhaust pipe
niin.
.
.00301 H.P.
.
3
Condition of valves and piston regarding leakage
Character of steam
J^uration
hrs.
Weight of feed-water consumed
Feed -water consumed per hour
steam
atmosphere
Pressure
Mean
in
.
lbs.
.
lbs.
lbs.
Revolutions per minute
Indicated horse-power
Feed- water consumed per
per hour
.
Tests.
A.
B.
C.
Ordinary
Ordinary
Ordinary
3
2,140
713.3
4
4,035
4
4,833
1,008.8
1,208.2
above
pipe
effective pressure
ins.
Fairly tight
Data and Results of Feed -Water
Tests.
ins.
3^
lbs.
.
.
.
.
.
.
.
.
.I.H.P.
I.
83
24.53
303.7
22.45
82.4
34.86
307.8
32.33
81.9
42.99
304.5
39.44
H. P.
lbs.
31.78
31.2
30.63
Measurements based on Sample Diagirams.
Tests.
A.
pressure above atmosphere
Corresponding steam-pipe pressure
Cut-off pressure above zero
Release pressure above zero
Mean effective pressure
Back pressure at mid stroke above
Initial
.
.
.
of
at cut-off
78.8
lbs.
83
lbs.
76.2
27.4
24.61
.
.
lbs.
.
.
lbs.
atmosphere
Proportion
lbs.
c.
77.3
82
75.5
32.5
34.79
79.5
81.8
78.1
37.3
43.12
lbs.
.8
.
lbs.
.
lbs.
.203
20.4
21.66
22.48
21.76
.642
.72
.762
.681
.698
.726
.7
.7
stroke completed
Steam accounted
for at cut-off
Stea'n accounted for at release
Proportion of feed water accounted for at cut-off
Proportion of feed water accounted for at release
....
....
Engine No. 23 has a
means
B.
single-slide valve
which
of a pressure-plate riding on the back,
105
.312
is
.378
23.33
22.24
balanced by
and the
cut-off is
ENGINE
106
TESTS.
the action of a shaft governor. Steam
suppUed from a horizontal return tubular boiler. A calorimThe piston was
eter test showed that it was practically dry.
fairly tight.
The valve showed some leakage. The load conA series of tests were made
sisted of a Sturtevant Blower.
under conditions of different loads, but practically constant
made automatic through
is
boiler pressure.
Another test in the same series with a load of 28.44 I. H. P.,
which is intermediate between the first and the second, gave a
feed-water consumption of 31.46 lbs. per I. H. P. per hour, and
the proportions of steam accounted for were respectively .685
and .694. In this series of tests the gradual improvement in
the
is
economy
also the
as the load is increased
counted for at the
as the cutroff
release
the
is
a noticeable feature, as
uniform increase in the proportion of steam accut-off.
becomes
later,
Another point to be noticed is that
amount of steam present at the
the
In
compared with that at cut-off is gradually reduced.
experiment the steam at release is the greater of the
first
two, while in the last
80-1
^
it is
the smaller.
ENGINE No. 23a
Head End
ENGINE No. 23b
Head End
20-
ENGINE
No. 24.
Simple Non-Condensing Engine.
Kind
Single valve
of engine
Number
of cylinders
1
Diameter of cylinder
Diameter of piston rod
14.5
ins.
2i
ins.
Stroke of piston
13
Clearance
12
m. e. p. one revolution per min.
Inside diameter of steam pipe
Condition of valves and piston regarding leakage
H. P. constant for
.
.
%
.0107
1 lb.
.
ins.
5
HP.
ins.
Fairly tight
Data and Results of Feed- Water Test
Ordinary
Character of steam
Duration
Weight
4.45
of feed-water
consumed
Feed-water consumed per hour
Pressure in steam pipe above atmosphere
Mean
effective pressure
hrs.
8,983
lbs.
2,018.6
lbs.
80.3
lbs.
23.22
lbs.
248.4
Revolutions per minute
I.H.P.
61.7
Indicated horse-power
Feed-water consumed per
I.
H. P. per hour
32.71
lbs.
Measurements based on Sample Diagrams.
above atmosphere
78.4
lbs.
Corresponding steam-pipe pressure
Cut-off pressure above zero
80.5
lbs.
74.1
lbs.
Release pressure above zero
20.6
lbs.
Mean
23.43
lbs.
2.6
lbs.
Initial pressure
effective pressure
Back pressure
at
mid stroke above atmosphere
Proportion of stroke completed at cut-off
Steam accounted for
Steam accounted for
.211
at cut-off
21.66
lbs.
at release
23.57
lbs.
Proportion of feed-water accounted for at cut-off
.662
Proportion of feed-water accounted for at release
.721
Engine No. 24
is
of the high-speed type,
with an unpacked
Steam was supplied from a horizontal return tubular boiler in what was
The valve was new,
believed to be a commercially dry state.
well fitted, and fairly tight.
The piston \^as also fairly tight.
The load consisted mainly of machinery for the manufacture of
piston valve controlled
by
a shaft governor.
woolen yarns.
108
ENGINE No. 24
80
60
Head End
-40
- 20
r-
80
60
Crank End
— 40
20
ENGINE
No. 25,
Simple Condensing Engine.
Kind
Four valve
of engine
Number
(Corliss)
2
of cylinders
26
Diameter of each cylinder
Diameter of each piston rod
ins.
ins.
3i
Stroke of each piston
5
ft.
Clearance
H. P. constant for one
3
%
lb.
m.
one revolution per minute
e. p.
H.P.
16
each cylinder
Inside diameter of steam pipe
8
ins.
Inside diameter of exhaust pipe
10
ins.
Condition of valves and pistons regarding leakage
Some leakage
Data and Results of Feed Water
Test.
Ordinary
Character of steam
Duration
Weight
1.75
of feed-water
consumed
Feed-water consumed per hour
Pressure in steam pipe above atmosphere
hrs.
24,416
lbs.
13.948
lbs.
82,9
lbs.
Vacuum in condenser
Mean effective pressure
25,9
ins.
36.29
lbs.
Revolutions per minute
53.9
625,6
Indicated horse-power
Feed-water consumed per
I. II.
P. per hour
I.
22.29
H.P.
lbs.
Measurements Based on Sample Diagrams.
Thuee Ends
One Km»
Noncondensixo. Condensing.
above atmosphere
Corresponding steam-pipe pressure
Cut-off pressure above zero
Release pressure above zero
Initial pressure
Mean
at
mid
lbs.
lbs.
10.
lbs.
.245
15.49
15,59
.
.
lbs.
.
.
,
lbs.
lbs.
lbs.
effective pressure
Back pressure
79.9
83.4
73.2
19.2
40.25
.
79.7
83.4
66.2
17.6
23.94
stroke, above or be-
low atmosphere
Proportion of stroke completed at cut-off
Steam accounted for at cut-off
Steam accounted for at release
Proportion of feed-water accounted for at
cut-off, average
Proportion of feed-water accounted for at
release, average
.
....
....
Engine No. 25 has a pair
into a jet condenser which
lbs.
+ 3.5
.24
21.17
22.23
r37
r40
of horizontal cylinders exhausting
is
operated by a direct connected
110
ENGINE
No.
25,
111
The cylinders were arranged for running one end
and it was under these conditions that the tests were made.
Steam is furnished by cylinder
boilers, and it is presumed that it was in a commercially dry
condition.
When the water was carried at an unusually low
point, a small portion of the shell became steam-heating surface, and the steam was found to be slightly superheated.
Two
of the steam valves showed some leakage.
The pistons also
leaked a small amount.
The remaining valves were fairly
tight.
The load consisted of cotton machinery.
air-pump.
of one cylinder non-condensing,
ENGINE No^25
r80
R.H.Cyl.
Head End
ENGINE
No. 26.
Simple Non-Condensing Engine.
Kind
Four valve
of engine
Number
of cylinders
Diameter
Diameter
1
of cylinder
IQk
ins.
2i
ins.
of piston rod
Stroke of piston
3
Clearance
6
H.P. Constant for one lb. m.e.p. one rev. per min
Condition of valves and piston regarding leakage
Character of steam
Duration
hrs.
Weight of feed-water consumed.
lbs.
Feed-water consumed per hour
lbs.
Pressure in steam pipe above atmosphere
lbs.
Mean effective pressure
lbs.
Revolutions per minute
I. H.P.
Indicated horse-power
Feed-water consumed per I. H.P. per hour, lbs.
.
.
.
.
.
%
03717 H.P.
....
Data and Results of Feed -Water
Test.
ft.
Leakage Test
A
Tests.
A.
B.
Ordinary
Ordinary
3.117
3.
7,207.
6,221.
2,073.7
2,312.2
74.2
25.17
75.8
70.9
32.61
74.
24.89
76.03
70.6
29.37
Measurements based on Sample Diagrams.
Test.
above atmosphere
Corresponding steam-pipe pressure
Cut-off pressure above zero
Release pressure above zero
Initial pressure
Mean
.
.
.
lbs.
.
.
.
lbs.
lbs.
lbs.
effective pressure
lbs.
at mid stroke above atmosphere
Proportion of stroke completed at cut-off
Steam accounted for at cut-off
Steam accounted for at release
Proportion of feed-water accounted for at
Back pres.
.
A.
B.
66.2
74.2
64.7
18.5
25.17
66.5
1.9
.237
lbs.
.
....
....
lbs.
lbs.
74.
65.5
18.3
24.89
1.7
.223
21.87
24.64
22.55
24.65
cut-off
.692
.745
.755
.839
Proportion of feed-water accounted for at
release
Engine No. 26 has double poppet steam valves, and plain
exhaust valves.
Steam is drawn from horizontal return
slide
tubular boilers.
The load was
a machine shop.
and piston were practically tight on
113
test B.
On
The valves
test
A
the
ENGINE
114
TESTS.
exhaust valve leaked badly, and during the interval between
the two
The
engine
10%
it
was repaired.
effect of
is
exhaust valve leakage on the economy of the
here clearly revealed.
less steam.
the diagrams
is
The
The
tighter engine used about
effect of the leakage
hardly noticeable.
upon the
lines of
ENGINE
No.
26a
60
40
Head End
20
60
40
Crank End
20
60-
40
ENGINE
No.
Head End
20-
60
40-
20
0-1
26b
Crank End
ENGINE
No. 27.
Simple Non-Condensing Engine.
Kind
Single valve
of engine
Number
of cylinders
Diameter
Diameter
1
of cylinder
of piston rod
Stroke of piston
Clearance
.
12*
ins.
2j
ins.
20
ins.
8
%
.01210 H, P.
H. P. constant for 1 lb. m. e. p. one revolution per minute
Considerable leakage
Condition of valves and piston regarding leakage
.
.
Data and Results of Feed- Water
.
Test.
Ordinary
Character of steam
3.088
Duration
Weight
of feed-water
consumed
4,374.5
Feed-water consumed per hour
Pressure in steam pipe above atmosphere
Mean
lbs.
1,418.0
lbs.
72.2
lbs.
effective pressure
18.
Revolutions per minute
hrs.
lo
lbs.
172.3
Indicated horse-power
Feed-water consumed per
.
,
I.
l.H. P.
38.1
.
H. P. per hour
37.21
lbs.
Measurements based on Sample Diagrams.
above atmo.sphere
Corresponding steam-pipe pressure
Cut-off pressure above zero
Release pressure above zero
08.8
Mean
Initial pressure
Back
effective pres.sure
pressiu-e at
mid stroke above atmosphere
lb.s.
3.5
lbs.
lbs.
2(J.74
lbs.
is
of
5(58
710
the high-speed class, with
the horizontal return tubular t}^e.
engine was confined mainly to the valve.
unpacked
The
boiler is
The leakage of the
The load consisted
tools.
The engine being
as it
some 75 ft. from
was not so favorable for
located at a distance of
the boiler, the condition of the steam
economy
lbs.
]8.1o
21.13
Engine No. 27
machine
2().4
for at cut-off
piston valve operated through a shaft governor.
of
lbs.
for at release
Proportion of feed-water accounted for at cut-off
Proportion of feed-water accounted for at release
of
lbs.
6(1 o
210
Proportion of stroke completed at cut-off
Steam accounted
Steam accounted
lbs.
72.2
might otherwise have been.
plains in part the poor showing.
116
Doubtless this ex-
ENGINE No. 27
60
Head End
40
-20
60
Crank End
-40
20
^
ENGINE
No. 28.
Simple Condensing Engine.
Kind
of engine
Number
Four valve
of cylinders
Diameter of cylinder
Diameter of piston rod
32i
ins.
4^
ins.
Stroke of piston
5
Clearance
2i
H. P. Constant for one
lb.
m.e.p., one rev. per minute
Condition of valves and piston regarding leakage
.
ft.
.
Data and Eesults of Feed - Water
%
H.P.
Some leakage
.2451
.
.
Test.
Character of steam
Ordinary
Duration
Weight
(Corliss)
l
.
6.1
of feed-water
consumed
hrs.
55,001
Feed-water consumed per hour
Pressure in steam pipe above atmosphere
lbs.
10,784.5
lbs.
70. 1
lbs.
Vacuum in condenser
Mean elf ective pressure
24.2
ins.
38.26
lbs.
Revolutions per minute
59.13
Indicated horse-power
Feed-water consumed per
554.4
II.
I.
P. per hour
I.
19.45
H.P.
lbs.
Meamirements based on Sample Diagrams.
above atmosphere
Corresponding steam-pipe pressure
Cut-off pressure above zero
Release pressure above zero
Initial pressure
Mean
(57.5
effective pressure
Back pressure
mid
below atmosphere
Proportion of stroke completed at cut-off
Steam accounted for at cut-off
Steam accounted for at release
Proportion of feed-water accounted for at cut-off
Proportion of feed-water accomited for at release
at
stroke,
Engine No. 28 exhausts into a
connected air-pump.
tubular type.
The
.
.
.
lbs.
61.5
lbs.
17.6
lbs.
38.26
lbs.
11.6
lbs.
271
15.20
lbs.
15.27
lbs.
781
785
jet condenser,
with direct
boilers are of the horizontal return
The steam valves were
was some small amount
.
lbs.
70.1
practically tight.
of leakage of the piston,
leakage of the exhaust valves.
and a
There
trifling
The load was cotton machinery.
118
ENGINE
No.
28
60
Head End
40
20
60-
40-
20-
010—
Crank End
ENGINE
No. 29.
Simple Condensing Engine.
Kind
Four valve
of engine
Number
(Corliss)
2
of cylinders
Diameter of each cylinder
Diameter of each piston rod
28
ins.
4
ins.
Stroke of each piston
5
ft.
Clearance
2i
H. P. Constant for one
lb.
m.
e. p.
one rev. per minute
Some leakage
Condition of valves and pistons regarding leakage
Data and Results of Feed -Water
Character of steam
Duration
Weight of feed-water consumed
Feed-water consumed per hour
Pressure in steam-pipe above atmosphere
Vacuum in condenser
Test.
R. H.
L. H.
Cylinder.
Cylinder.
Ordinary
5.32
76,053
14,295.7
hrs.
....
....
Mean
%
H.P.
.1846
lbs.
lbs.
67.1
lbs.
.
27.3
31.26
60.27
347.8
ins.
effective pressure
lbs.
Revolutions per minute
Indicated horse-power
I. H.P.
Indicated horse-power, whole engine
I. H.P.
Feed-water consumed per I. H. P. per hour lbs.
......
19.26
60.27
214.3
562.1
25.43
.
Measurements Based on Sample Diagrams.
K. H.
L.
Cylinder
pressure above atmosphere
Corresponding steam-pipe pressure
Cut-off pressure above zero
ReleEise pressure above zero
Initial
Mean
.
.
.
lbs.
.
.
.
lbs.
lbs.
lbs.
effective pressiu-e
Back pressure
mid
low atmosphere
at
lbs.
11.
Cylinder.
61.9
63.7
67. 1
67.6
13.9
31.26
67.7
16.6
19.26
stroke, above or be-
...
....
....
....
Proportion of stroke completed at cut-off
Steam accounted for at cut-off
Steam accounted for at release
Steam accounted for at cut-off, both cylinders, average
Steam accounted for at release, both cylinders, average
Proportion of feed-water accounted for at
lbs.
—12.1
+2.8
.202
.
lbs.
lbs.
.187
14.46
14.86
21.82
24.31
lbs.
17. 27
lbs.
18. 37
379
cut-off
.(
Proportion of feed-water accounted for at
release
•
120
r22
ENGINE
121
No. 29.
Engine No. 29 has a pair of cylinders, one
of
which
is
non-
condensing, and the other exhausts into a jet condenser with
direct connected air-pump.
Steam
return tubular boilers, and
presumably in a commercially dry
state.
is
is
drawn from horizontal
There was a small amount of leakage in the valves of
both cylinders, not only steam valves but exhaust valves, and
some piston leakage.
The engine operated
ing in connection with water-wheels.
a cotton-mill, work-
ENGINE
No.
29
60
R.H.Cyl.
40
Head End
20-
0-"
-60
R.H. Cyl.
Crank End
-40
-20
L.H.Cyl.
Head End
ENGINE
No. 30.
Simple Condensing Engine.
Kind
Four valve
of engine
Number
of cylinders
2
Diameter of cylinder
Diameter of piston rod
16
ins.
ins.
2i
Stroke of piston
3
Clearance
5
H. P. constant for one lb. m. e.
Inside diameter of steam pipe
p.
ft.
%
one rev. per min., each
.0361 H.P.
Inside diameter of exhaust pipe
Condition of valves and pistons regarding leakage
.
Data and Besults of Feed-Water
5
ins.
6
ins.
Some leakage
.
Test.
Ordinary
Character of steam
Duration
hrs.
5.
Weight of feed-water consumed
Feed-water consumed per hour
Pressure in steam pipe above atmosphere
.'
Vacuum in condenser
Mean effective pressure
•
.
.
.
.
Kevolutions per minute
22,055
lbs.
4,411
lbs.
83.4
lbs.
26.7
ins.
31.27
lbs.
90.4
Indicated horse-power
205.9
Feed-water consumed per
I.
H. P. per hour
I.
H.P.
21.42
lbs.
Measurements based on Sample Diagrams.
Initial pressure
above atmosphere
74.4
Ibi.
Cut-off pressure above zero
75.0
lbs.
Release pressure above zero
14.9
lbs.
Mean
31.16
lbs.
effective pressure
Back pressure
at
mid stroke below atmosphere
Proportion of stroke completed at cut-off
Steam accounted
Steam accounted
— 11.15
lbs.
.130
for at 'cut-off
13.81
lbs.
for at release
16.45
lbs.
Proportion of feed-water accounted for at cut-off
.645
Proportion of feed-water accounted for at release
.760
Engine No. 30 has a pair of cylinders each having two steam
valves and two exhaust valves, all being slide valves.
The
condenser
is of
the jet type operated by an independent air-pump
driven by steam taken from the engine-pipe.
The quantity
of
steam used by the condenser was determined by an independent
test
and allowed
for.
Steam
tube boilers, and a separator
is
123
is
furnished by vertical water
fitted to the
main steam
pipe.
ENGINE
124
No
TESTS.
water collected in the separator, and the steam
to be commercially dry.
The
inder showed some leakage.
is
presumed
valves and pistons of each cyl-
The load
consisted of
dynamos
furnishing current for electric lighting.
Engine No. 30 belongs to the same plant as Nos. 35 and 36,
and it is supplied with steam from the same boiler plant.
ENGINE No. 30
ENGINE
No. 31.
Simple Non-Condensing Engine.
Kind
Four valve
of engine
Number
...
of cylinders
Diameter of each cylinder
Diameter of each piston rod
Stroke of each piston
Clearance
,
16
ins.
42
.-
.
.....'
ins.
%
2.5
.
Data and Eesidts of Feed- Water
.
.
.
.
effective pressure
Fau-ly tight
Tests.
I.
B.
Heavy
Load.
Ordinary
hrs.
4.
2.
lbs.
10,807.
17,746.
8,873.
lbs.
lbs.
lbs.
H.P. per hour
ins.
7
Ordinary
....
....
H.P.
.042
Light Load.
Character of steam
Duration
Weight of feed-water consumed
Feed-water consumed per hour
Pressure in steam pipe above atmosphere
I.
.
A.
ChAKACTKK UK LoAU.
Revolutions per minute
Indicated horse-power
Feed-water consumed per
ins.
21
H.P. constant for one lb. m.e.p. one rev. per minute
Inside diameter of steam pipe
Condition of valves and pistons regarding leakage
Mean
(Corliss)
2
H.P.
lbs.
2,724.2
101.8
5.03
87.6
37.02
73.63
98.6
48.4
84.9
342.43
26.91
Measurements based on Sample Diagrams.
Initial
pressure above atmosphere
Light Load.
.
.
.
Cut-off pressure above zero
Release pressure above zero
Mean
B.
A.
Character of Load.
lbs.
lbs.
80.5
81.9
lbs.
effective pressure
at mid stroke above atmosphere
Proportion of stroke completed at cut-off
Steam accounted for at cut-off
Steam accounted for at release
Proportion of feed-water accounted for at
cut-off
Proportion of feed-water accounted for at
release
Back pres.
.
lbs.
5.4
lbs.
2.
.041
.
....
....
lbs.
28.16
lbs.
.382
Heavy
Load.
91.6
94.8
31.4
40.26
»
2.6
.323
20.63
21.55
.796
.832
Engine No. 31 has a pair of cylinders drawing steam from
boilers.
There was only a small
amount of leakage in any of the valves and pistons. The
horizontal return tubular
126
ENGINE
12T
No. 31.
engine was employed in driving a line-shaft to which were
belted
The
dynamos supplying current
for electric lighting.
tests reported in the principal table were two in number,
one of which was made with a friction load consisting of the
shafting and
empty dynamos, and the other with
a full load.
Tests on the same engine at intermediate loads gave the
lowing principal results
Indicated
Horse
Power.
100.4
146.2
222.2
287.1
:
Feed-Water
Per I.H.P.
Per Hoi'R.
38.38
31 .43
25.83
25.39
Proportion
OF Stroke
Completed
AT Cut-off.
.084
.121
.178
.231
Proportion
OF Feed-
Water
ACCT.
FOR AT Cutoff.
.509
.588
.709
.745
fol-
ENGINE
No. 31a
80
h
RH.Cyl. Head End
60
40
- 20
80
60
40
RH.Cyl. Crank End
20
<^
r
100
80
h60
40
[-20
L.H.Cyl. Crank
End
ENGINE No. 31b
80
R.H.Cyl.Head End
h60
-40
-20
L-
— 80
-60
RH.Cyl.Crank End
-40
20
L-
-80
L.H.Cyl.Head End
-60
-40
20
L-
80
L.H.Cyl. Crank
End
-60
-40
20
FEED -WATER
TESTS.
COMPOUND ENGINES.
IThese engines are
all
of the automatic cut-off type, with fly-ball governor,
unless otherwise stated.]
131
ENGINE
No. 32.
Compound Condensing Engine.
H. P.
Cylinder.
Kind
L. P.
Cylinder.
Four valve
of engine
Number
of cylinders
Diameter of cylinders
Diameter of piston rod
Stroke of piston
ins.
ins.
1
26
4
48
4
3
4
3
ft.
Clearance
H. P. constant for 1 lb. m. e. p. one revolution per min
Ratio of areas of cylinders
Inside diameter of steam pipe
Inside diameter of exhaust pipe
Condition of valves and pistons regarding
leakage
....
(Corliss)
1
%
H.P,
5
.5454
3.43
14
14
.159
1
8
14
ins.
ins.
Tight
Fairly tight
Data and Results of Feai - Water
Test.
Ordinary
Character of steam
Duration
Wejglit of feed-water consumed
Feed-water consumed per hour
Pressure in steam pipe above atmosphere
Pressure in receiver
Vacuum in condenser
Revolutions per minute
Mean effective pressure, H. P. cylinder
4.5
hrs.
*44, 436
lbs.
874
lbs.
9,
94.8
lbs.
6.4
lbs.
27.2
ins.
52.3
41.14
lbs.
9.27
lbs.
342.1
H.P.
Mean
effective pressure, L. P. cylinder
Indicated horse-power, H. P. cylinder
Indicated horse-power, L. P. cylinder
Indicated horse-power, whole engine
Feed-water consumed per I. H. P. per hour
264.43 H.P.
606.53 H.P.
*16.28
lbs.
Measurements based on Sample Diagrams.
H.P.
Cylinder.
above atmosphere
Con-esponding steam-pipe or receiver
Initial pressure
.
pressure
Cut-off pressure above zero
Relea.se pressure above zero
Mean
.
....
....
effective pressure
Back pressure
at
mid
lbs.
89.4
lbs.
94.2
91.9
28.4
41.26
lbs.
lbs.
lbs.
L. P.
Cylinder.
6.0
6.3
12.6
7.5
9.28
stroke, above or
below atmosphere
Proportion of stroke completed at cut-off
Steam accounted for at cut-off
Steam accounted for at release
Proportion of feed-water accounted for
lbs.
.305
.
.
.
lbs.
.
.
.
lbs.
at cut-off
+ 8.1
12.60
12.84
-10.8
.544
11.78
12.98
.774
.723
.789
.797
Proportion of feed-water accounted for
at release
Includes steam used by circulating-pump.
133
ENGINE
134
TESTS.
Engine No. 32 is a cross-compound, having unjacketed horizontal cylinders and unjacketed receiver.
A surface condenser
is employed, and the air-pump is operated by direct connection
The circulating-pump is a duplex steam
with the engine.
9" X 10" X 12", and the steam it used is included in that
pump
reported.
boilers,
tion.
The engine
and
it
is
is
furnished with steam from sectional
presumed
to be in a
commercially
dr}^ condi-
In the matter of leakage the engine was in excellent
condition throughout with the exception of the piston in the
which leaked a small amount.
The
The feed-water consumption
load consisted of a cotton-mill.
was determined by measuring the water discharged by the airpump.
high-pressure
cylinder,
ENGINE
No. 32
— 100
— 80
H.P.
Head End
-60
-40
h-20
-
-100
-80
H.P.
Crank End
h-60
40
-20
I—
5-
L.P.
Head End
OH
510-
50510-
UP. Crank End
ENGINE
No. 33.
Compound Condensing Engine.
H.P.
Cylixder.
......
Kind
of engine
of cylinders
Diameter of cylinder
Stroke of piston
Number
Single valve.
....
1
ins.
.
20
:^
12
ins.
Clearance
%
H. P. Constant for one lb. m. e. p.
one rev. per min
H.P.
Ratio of areas of cylinders
Condition of valves and pistons
regarding leakage
.
L.P.
Cylinder.
12
9
33
.00952
2.78
.00342
1
.
....
Tight.
Data and Results of Feed - Water
Tight.
Tests.
li.
Te.st.
A.
Conditions reqabdin& use of Condenser.
Condensing
CONDENSING
Character of steam
Duration
hrs.
Weight of feed-water consumed
lbs.
Feed-water consumed per hour
lbs.
Press, in steam pipe above atmos. lbs.
Vacuum in condenser
ins.
Revolutions per minute
Mean effective pressui-e, H.P. cyl. lbs.
Mean effective pressure, L.P. cyl. lbs.
Indicated horse-power, H.P. cyl. H.P.
Indicated horse-power, L. P. cyl. H.P.
Indicated H. P., whole engine
H.P.
Feed-water cons, per I. H. P. per hr. lbs.
Ordinary
Ordinary
8
34,555
4,319.4
129.3
41,562
5,195
128
.
.
....
....
totals
8
25
296.1
57.21
20.34
115.85
114.69
300.
53.53
20.73
109.84
118.41
228.25
18.92
.
The above are the
N<JN-
230.54
22.53
ami averages for the two engiues.
Measurements based on Sample Diagrams.
H.P.Cyl. L.P. Cyl. H.P.CYL. L.P. Cyl.
Tests,
Initial pressure above atmosphere
Corresponding steam-pipe pressure
Cut-off pressure above zero
Release pressm-e above zero
lbs.
122.9
lbs.
132.
122.
Meau
.
lbs.
.
.
lbs.
.
.
lbs.
67.9
53.4
.
lbs.
+ 20.8
.
lbs.
.
lbs.
.
effective pressure
Back pressure
at
.
33.9
121.5
52.8
136.
27.1
17.8
20.71
124.3
82.3
56.44
35.8
27.4
20.25
mid stroke above
or below atmosphere
of stroke completed
.
-11.
+ 29.4
+ 1.1
Proportion
.38
at cut-off
Steam accounted
Steam accounted
Proportion
ed for
Proportion
ed for
for at cut-off
for at release
of feed water accountat cut-off
of feed water accountat release
....
....
15.21
16.24
.
180
.521
12.14
1321
.532
20.13
28.2
.66
16.54
17.76
.804
.642
.894
.734
.859
.700
.925
.789
ENGINE
137
No. 33.
two independent engines which
These engines are single-acting
with vertical unjacketed cylinders, and provided with a single
Engine No. 33 consists
of
were tested simultaneously.
piston valve fitted with ring packing, one valve serving for
A jet condenser is used
which is common to both engines and it is operated by an independent air-pump, which takes steam from the main supply
pipe.
The boiler feed-pump is also supplied from the main
both high- and low-pressure cylinders.
;
The quantity
pipe.
of
steam used by these two pumps was
determined by independent
tests
furnished by water tube boilers
in one case
y^j
of
1%
;
and allowed
Steam is
showed
the other 1tV%The
for.
and a calorimeter
of moisture,
and
in
test
valves and pistons of both engines were practically tight.
load consisted of
test
dynamos employed
in electric lighting.
The
One
was made with the engines running condensing, and an-
other running non-condensing, the condenser being stopped.
The
difference in
economy
represented by 3.61
lbs.
which, in round numbers,
of feed-water per
is
due to the use
by air-pump, is
H. P. per hour,
of these engines,
of a condenser not allowing for steam used
20%
I.
of the quantity
used when
was run condensing. The results of these tests cannot be passed by without noticing the marked difference in the
porportion of steam accounted for at the cut-off under the two
the engine
conditions of operation; and the loss of steam between
the
high-pressure cylinder and low-pressure cylinder in both cases.
ENGINE No. 33a
1—120
-
00
— 40
40
—
20
—
-
120-
80-
40-
40-
20-
0lO-i
10
J
ENGINE No. 33b
120
-
80
40
60
40
20
I—
120-
80-
40.
0-
60-
40-
20-
0—
ENGINE
No. 34.
Compound Condensing Engine.
H.P. Cylindeb.
L.P.
Cylixdk
Kind
Four valve
Number
1
1
22
44
of engine
of cylinders
Diameter of cylinder
Diameter of piston rod
Stroke of piston
ins.
ins.
ft.
%
Clearance
H. P. constant for one lb. m. e. p. one
H.P.
rev. per min
Ratio of areas of cylinders
ins.
Inside diameter of steam pipe
ins.
Inside diameter of exhaust pipe
Condition of valves and pistons regarding leakage
....
.
2.:i
.1138
1
.
7
.
.
9
Some leakage
Data and Results of Feed - Water
Character of steam
Duration
Weight of feed-water consumed
Feed-vsrater consumed per hour
Pressure in steam pipe above atmosphere
Pressure in receiver above atmosphere
Vacuum in condenser
Revolutions per minute
Mean effective pressure H. P. cylinder
Ordinary
lbs.
lbs.
7.5
lbs.
25.5
ms.
41.48
10.08
321.39
315.09
636.48
13.28
'
.
Indicated horse-power L. P. cylinder
Indicated horse-power, whole engine
Feed-water consumed per I. H. P. per hour
.
lbs.
(58.08
Mean
.
hrs.
8,453.2
116.1
.
.
tight
4
33,813
.
.
.4592
4.04
13
16
Practically
Test.
....
....
.
31
5
5.9
3i
5
.
effective pressure L. P. cylinder
Indicated horse-power H. P. cylinder
(Corliss)
lbs.
lbs.
H.P.
H.P.
H.P.
lbs.
Measurements based on Sample Diagrams.
H.P.
CVLIXDER.
Initial pressure above atmosphere
Corresponding steam-pipe or receiver
.
pressure
Cut-off pressure above zero
Release pressure above zero
Mean
Back
.
....
....
effective pressure
pressure at mid stroke
L.P.
Cylinder.
lbs.
108.8
9.1
lbs.
114.2
lbs.
104.
lbs.
29.1
7.4
16.7
6.8
lbs.
41.26
10.05
above or
below atmosphere
Proportion of stroke completed at cut-off
Steam accounted for at cut-off
lbs.
Steam accovinted
for at release
+ 11.3
.26
.
.
.
lbs.
.
.
.
lbs.
10.48
11.3
-11.8
.325
10.06
10.98
Proportion of feed-water accounted for
at cut-off
.789
.758
.852
.827
Proportion of feed-water accounted for
at release
140
ENGINE
Engine No. 34
is
a cross
141
No. 34.
compound with horizontal jacketed
Steam supplied to the low-
cylinders and unjacketed receiver.
pressure
cylinder
first
through the jacket space,
circulates
entering at the bottom at a central opening.
drained into tanks, which are
operated by the engine.
source
about 7
during the tests
%
The
jackets are
emptied by means
The water
amounted
of the total quantity of
of condensation
to
600
lbs.
of
pumps
from
this
per hour, or
steam used by the engine.
The condenser is of the jet type with a direct connected airpump. Steam is supplied from horizontal return tubular boilA calorimeter test showed that the amount of moisture
ers.
was tV of 1 %.
The exhaust valves and pistons of both
cylinders,
and the steam valves
were found to be practically
of the low-pressure cylinder
tight.
The steam valves of the
The load con-
high-pressure cylinder showed some leakage.
sisted of cotton machinery.
ENGINE JMo. 34.
—100
80
H.P.
Head End
60
—
40
-
20
-
-100
-80
H.P.
Crank End
-60
-40
-20
1—
10-
L.P.
5-
Head End
05lO-i
L.P.
Crank End
ENGINE
No. 35.
Compound Condensing Engine.
H. P.
CVLT^'DER.
Kind
L. P.
Cylinder.
Single valve.
of engine
of cylinders
Diameter of cylinder
Diameter of piston rod
Number
ins.
1
1
13
22
IH
ins.
ins.
Stroke of piston
%
Clearance
Horse-power constant for one lb. m.e.p.
H.P.
one revolution per minute
Ratio of areas of cylinders
ins.
Inside diameter of steam pipe
ins.
Inside diameter of exhaust pipe
Condition of valves and pistons regarding leakage
.
.
18
7
.0119
.
....
.
.
.
.
.
2j
18
10
.0344
2.89
1
41
6.
Considerable
leakage
Data and Results of Feed-Water
Character of steam
Duration
Weight of feed-water consumed
Feed-water consmned per hour
Pressure in steam pipe above atmosphere
Vacuum in condenser
Revolutions per minute
Mean effective pressure H. P. cylinder
Mean effective pressure L. P. cylinder
Indicated horse-power II. P. cylinder
Indicated horse-power L. P. cylinder
Indicated horse-power, whole engine
Feed-water consumed per I. H. P. per hour
Considerable
leakage
Test.
Ordinary
5
hrs.
16, 375
lbs.
3, 275
lbs.
105.2
lbs.
ms.
28
197.1
32.57
10.63
76.4
72.1
148.5
H.P.
H.P.
H.P.
22.05
lbs.
lbs.
lbs.
Measurements based on Sample Diagrams.
H.P.
Cylixueu.
above atmosphere
Corresponding steam-pipe or receiver
Initial pressure
.
pressure
Cut-off pressure above zero
Release pressure above zero
Mean
.
....
....
effective pressure
Back pressure
at
of
lbs.
96
11.5
lbs.
104
84.6
43.6
16.9
lbs.
lbs.
lbs.
stroke
lbs.
completed
11.
10.82
+ 18
-9.6
at
cut-off
Steam accounted
Steam accounted
3.3.21
mid stroke above or
below atmosphere
Proportion
L. P.
Cylinder.
..382
for at cut-off
for at release
.
.
.
lbs.
1.3.73
.
.
.
lbs.
14.95
.505
13.93
14.68
Proportion of feed-water accounted for
at cut-off
.623
.632
.678
.666
Proportion of feed-water accounted for
at release
........
143
ENGINE
144
Engine No. 35
TESTS.
a horizontal cross-compound
is
unjacketed
engine, provided with a shaft governor operating on the cut-off
of the high-pressure
cylinder.
type without packing.
A
jet
The
valves are of the piston
condenser
is
used operated by an
independent air-pump driven with steam taken from the engine
used, as also that consumed by the
was determined by independent tests and
allowed for. Steam is supplied from vertical water-tube boilers, and a separator placed in the steam pipe secured what was
The steam showed no
believed to be commercially dry steam.
The valve in each cylinder was found to leak
superheating.
badly.
The piston of the high-pressure cylinder was fairly
tight.
Owing to the leakage of the low-pressure valve no
leakage observations could be made upon the low-pressure
piston.
The load consisted of dynamos furnishing current for
pipe.
The quantity thus
boiler feed-pump,
electric lighting.
There
is
a close agreement between the steam accounted for
by the indicator
in view of the
not
known
which might be surprising
fact that the cylinders are unjacketed, were it
in the
two
cylinders,
that the steam valve of the high-pressure cylinder
showed considerable leakage. Some of the steam shown on
the low-pressure diagram was undoubtedly due to this cause.
ENGINE No. 35
lOO-i
80-
H.P.
Head End
60-
40-
20-
,-100
80
H.P.
Crank End
— 60
— 40
20
L.P.
10
Head End
5
\—
5
10
10-
50510-
L.P.
Crank End
ENGINE
No. 36.
Compound Condensing Engine.
H. P.
L. P.
Cylinder.
Cylinder.
.
Four valve
Kind
of engine
of cylinders
Diameter of cylinder
Diameter of piston rod
Stroke of piston
Number
.
ins.
.
ins.
.
ft.
....
%
Clearance
H. P. constant for one lb. m. e. p. one
revolution per minute
H.P.
Ratio of areas of cylinders
ms.
Inside diameter of steam pipe
ms.
Inside diameter of exhaust pipe
Condition of valves and pistons regar ding leakage
1
16
3
4
2
32
3H
4
4
.
.
.
.
.
.
.
.
.0479
1.00
.
.
.
6
.1937
4.04
12
.
Practically tight
•
Data and Results of Feed - Water
1
Test.
Ordinary
Character of steam
Duration
Weight of feed- water consumed
Feed-water consumed per hour
Pressure in steam pipe above atmosphere
Pressure in receiver above atmosphere
Vacuum in condenser
Revolutions per minute
Mean effective pressure, H. P. cylinder
Mean
(Corliss)
1
5.05
27,133
5,373
126.8
effective pressure, L. P. cylinder
Indicated horse-power, H-. P. cylinder
Indicated horse-power, L. P. cylinder
Indicated horse- power, whole engine
Feed-water consumed per I. H. P. per hour
hrs.
lbs.
lbs.
lbs.
8
lbs.
27.4
74.9
ins.
58.29
11.79
211.6
170.9
382.5
14.05
lbs.
lbs.
H.P.
H.P.
H.P.
lbs.
Measurements based on Sample Diagrams.
H.P.
Cylinder.
Initial pressure
above atmosphere
Cut-off pressure above zero
Release pressure above zero
Mean
effective pressure
at mid stroke,
Back pressure
.
.
....
....
lbs.
116.5
120.7
39.4
59.4
lbs.
+ 9.9
lbs.
lbs.
lbs.
L.P.
Cylinder.
7
18.4
7.4
11.97
above or
below atmosphere
Proportion of stroke completed at cut-off
Steam accounted for at cut-off
Steam accounted for at release
Proportion of feed-water accounted for
.
.
.
lbs.
.295
10.78
.
.
.
lbs.
12.
at cut-off
-13.
.337
8.98
10.42
.767
.64
.853
.741
Proportion of feed-water accounted for
at release
146
ENGINE
Engine No. 36
is
147
No. 36.
a cross-compound horizontal engine with
steam jacketed cylinders and a
direct connected air-pump.
The
jet
condenser operated by a
jacket spaces in each cylinder
form a thoroughfare through which the steam is suppUed to the
respective steam chests, the steam first entering the bottom of
During the test the drain-pipes
the jacket at a central point.
provided for carrying
and
this
all
jackets
effect the
off the
water of condensation were closed,
Whatever
might otherwise have produced was thus
water passed over into the cylinder.
and the engine may be considered as practically unSteam is supplied from vertical water tube-boilers,
jacketed.
and a separator is provided in the main steam pipe. For a
short period during the test, water accumulated in the sepaFor
rator, and its quantity was determined and allowed for.
the balance of the test there was no accumulation, and the
steam is presumed to be commercially dry. The valves and
nullified,
tight.
The loaddynamos supplying current for electric lighting.
Engine No. 36 belonged to the same plant as Nos. 30 and 35.
The behavior of the steam in its passage through the cylinders which the analysis of the indicator diagrams reveals is of
unusual interest. The increase in the amount of steam shown
at release over cut-off is very large in both cylinders, and the
loss of steam which the low-pressure cylinder shows is a marked
pistons
of
both cylinders were practically
consisted of
feature.
These actions
may
be attributed to the effect of the
jacket-water in the cylinders combined with the cooling action
which always takes place when steam passes from a high
low-pressure cylinder, where no means
cylinder condensation.
fected
to a
provided for reducing
In this case the quantities are unaf-
by steam which leaked,
practically tight.
is
all
the valves and pistons being
ENGINE No. 36
-120
-100
-80
-60
40
20
120-1
100-
H.P. Crank End
80H
60-
4020-
0-
lo-n
L.P.
Head End
50510-
L.P.
10
Crank End
5
-
5
10
ENGINE
No. 37.
Compound Condensing Engine.
H.P.
Cylinder.
Four valve
Kind
of engine
of cylinders
Diameter of cylinder
ins.
Diameter of pi^on rod
ins.
21
ft.
Stroke of piston
%
Clearance
H. P. constant for 1 lb. m. e. p. one
H.P.
revolution per minute
Ratio of areas of cylinders
Condition of valves and pistons regarding leakage
4h
2h
L. P.
Cylinder.
(Corliss)
Number
.
.
.
32
j2i
4^
2h
.2162
3.774
.0573
.
....
1
Fairly tight.
Data and Results of Feed- Water
Test.
Ordinary
Character of steam
Duration
-^
.
consumed
Feed-water consumed per hour
Weight
of feed-water
3,122.
Pressure in steam pipe above atmosphere
Pressure in receiver above atmosphere
Vacuum
in condenser
,
Revolutions per minute
Mean
Mean
0.833
hrs.
lbs.
3,746
lbs.
108
lbs.
2
lbs.
27
ins.
59
H. P. cylinder
45.47
effective pressure, L. P. cylinder
9.83
lbs.
154.28
effective pressure,
lbs.
Indicated horse-power, L. P. cylinder
125.85
Indicated horse-power, whole engine
280.13
H.P.
H.P.
H.P.
13.37
lbs.
Indicated horse-power, H. P. cylinder
Feed-water consumed per
I.
H. P. per hour
Measurements based on Sample Diagrams.
H.P.
Cylinder.
Steam accounted for
Steam accounted for
at cut-off
at release
.
,
.
lbs.
.
.
.
lbs.
9,8
10.78
L. P.
Cylinder.
10.48
10.94
Proportion of feed-water accounted for
at cut-off
.732
.784
.806
.818
Proportion of feed-water accounted for
at release
Engine No. 37
is
a tandem horizontal
ders and heads steam jacketed.
type,
compound with cylinThe condenser is of the jet
operated with an air-pump connected to the engine.
149
ENGINE
150
TESTS.
Steam is supplied from vertical boilers, which gave steam that
was at times slightly superheated, and at other times in its ordinary condition. The feed-water was measured on the test by
water-glass observations, the water being
point, then shut off,
needed replenishing.
amounted
to
248
total quantity
lbs.
and the
test
first
pumped
to a high
continued until the boilers
The water drained from
the
per hour, or in round numbers,
used by the engine.
The load
7%
jackets
of the
consisted mainly
of rubber grinding machinery.
The
and the short duration of
would be
the test,
if the load had been steady and the water had been measured
The sample indicator diagrams which are
for a longer period.
here presented, owing to the fluctuating load, must be regarded
as showing the general distribution of the steam in the cylinvariable character of the load,
make
the results less accurate than they
ders rather than precise average samples of the work.
When
the jackets were shut
off,
the
distribution
steam was affected in a noticeable degree.
between the steam shown at release and
increased.
The
cut-off
of
the
difference
was greatly
ENGINE No. 37
plOO
-80
H.P.
Head End
-60
40
20
-100
-80
H.P.
Crank End
60
h40
20
&-1
L.P.
Head End
05-
10-
5-1
0510-
L.P.
Crank End
ENGINE
No. 38.
Compound Condensing Engine.
H.P.
Cylinder.
Four valve
Kind
of engine
of cylinders
Diameter of cylinder
Diameter of jM^ton rod
Stroke of piston
Number
L.P.
Cylinder.
(Corliss)
1
ins.
44
22
ins.
3.5
3.5
ft.
5
2.5
5
%
Clearance
H. P. Constant for one lb. m.e.p., one
H.P.
rev. per minute
Ratio of areas of cylinders
Condition of valves and pistons regarding leakage
.0114
....
1
Practically
tight
Data and Results of Feed -Water
2.5
.0459
4.03
Excessive
leakage
Test.
Ordinary
Character of steam
Duration
Weight of feed- water consumed
Feed-water consumed per hour
Pressure in steam pipe above atmosphere
Pressure in receiver
Vacuum in condenser
Revolutions per minute
Mean effective pressure, H. P. cylinder
Mean
effective pressure, L. P. cylinder
Indicated horse-power, H. P. cylinder
Indicated horse-power, L. P. cylinder
Indicated horse-power, whole engine
Feed-water consumed per I. H. P. per hour
8.58
118,927
13,861
108.9
8.4
23.6
62,14
61.53
9.87
hrs.
434.6
281.4
716
19.36
H.P.
H.P.
H.P.
lbs.
lbs.
lbs.
lbs.
ins.
lbs.
lbs.
lbs.
Measurements Based on Sample Diagrams.
H.P.
Cylinder.
Initial pressure
above atmosphere
Cut-off pressure above zero
Release pressure above zero
Mean
Back
.
.
....
....
effective pressure
pressure at mid stroke
of
Steam accounted
Steam accounted
stroke
lbs.
lbs.
lbs.
112
111
45.7
62.08
8
J6.8
6.2
9.84
above or
below atmosphere
Proportion
lbs.
L.P.
Cylinder.
lbs.
completed
for at cut-off
for at release
+ 10
-11
at
.
.
.
lbs.
.
.
.
lbs.
.377
13.07
12.76
.381
8.42
8.67
Proportion of feed-water accounted for
at cut-off
.675
.435
.659
.448
Proportion of feed-water accounted for
at release
152
ENGINE
153
No. 38,
compound. The cylinand the intermediate receiver, which is
The
a chamber 30" in diameter and 8' high, is also jacketed.
arrangement of the jacket^piping is such that the drain pipe of
the high-pressure jacket supplies the low-pressure jacket, and
the drain pipe of this supplies the receiver jacket, and their
Engine No. 38
is
a horizontal cross
ders are steam-jacketed,
sizes are so proportioned that there is a continual reduction of
pressure from one point to the next, and consequently a con-
tinuous circulation.
The engine
is fitted
operated by a direct connected air-pump.
with a
jet
Steam
is
condenser
furnished
by horizontal return tubular boilers located at a distance of
some 200 feet. The water of condensation which collects in
the steam pipe is carried back to a feed tank in the boiler-room,
and steam used by the feed pump exhausts into the same tank.
There was some leakage of joints in the steam piping which
The valves and pistons of the highhas not been allowed for.
pressure cylinder were practically tight.
The
valves of the
low-pressure cylinder were tight, but the piston contained a
loosely fitting packing ring and leaked very badly.
The
load
consisted of cordage machiner}\
The interest in this test centers upon the effect which was
produced by excessive leakage through the low-pressure piston.
In a well jacketed engine the steam accounted for by the indicator
is
nearly as great in the low-pressure cylinder as in the
high pressure cylinder.
.675 to .435, or
and
24%
this is evidently
In this case there
of the total
due
is
a reduction from
weight of steam consumed,
to the leakage referred to.
ENGINE No. 38
I20-,
100
80-1
H.P.
Head End
60
40 H
20
0-J
120
-100
H.P. Crank End
-80
-60
-20
-0
(- 10
L.P.
Head End
5
I-
6
10
10
5
6
10
L.P.
-I
Crank End
ENGINE
No. 39.
Compound Condensing Engine.
H.
L. P.
P.
Cylinder.
Kind
of engine
of cylinders
])iameter of cylinder
Diameter of piston rod
Stroke of piston
Cylinder.
Single valve
Number
ins.
1
1
13
26
m
ins.
ins.
18
%
7
Clearance
Horse-power constant for one lb. m.e.p.
H.P.
one revolution per minute
.
....
Ratio of areas of cylinders
Condition of valves and pistons regarding leakage
Data and
18
10
.0019
.
.
2*
1
Considerable
leakage
.048
4.03
Considerable
leakage
Results of Feed -Water Test.
Ordinary
Character of steam
Duration
Weight
2.85
of feed-water
consumed
Feed-water consumed per hour
Pressure in steam pipe above atmosphere
Vacuum
in condenser
effective pressure
lbs.
120.6
lbs.
H. P. cylinder
,
.
.
.
.
.
ins.
195.3
.
effective pressure L. P. cylinder
Indicated horse-power
lbs.
3,973.7
27
Revolutions per minute
Mean
Mean
.
43.75
lbs.
12.68
lbs.
P. cylinder
101.7
Indicated hor.se-power L. P. cylinder
118.9
IT.
Indicated horse-power, whole engine
Feed-water consumed
hrs.
11,325
i)er I.
220.0
H. P. per hour
....
H.P.
H.P.
H.P.
18.01
Measurements based on Sample Diagrams.
H.P.
Cylinder.
Initial pres.sure
above atmosphere
Cut-off pressure above zero
lielease pressure above zero
effective pressure
Back pressure at mid stroke,
.
.
....
....
Mean
lbs.
lbs.
lbs.
lbs.
above or
below atmosphere
Proportion of stroke completed at cut-off
Steam accounted for at cut-off
Steam accounted for at release
lbs.
115.5
104.9
55.4
43.1
.
.
lbs.
.
.
.
lbs.
15
20.0
10.3
12.69
-
+ 23
.396
.
L. P.
Cylinder.
11.33
12.3
10.5
.387
12.49
12.49
Proportion of feed-water accounted for
at cut-off
.629
.094
.683
.094
Proportion of feed-water accounted for
at release
155
lbs.
156
ENGINE
.
Engine No. 39
is
TESTS.
a single valve, cross
compound, unjacketed
engine, with a shaft governor operating on the cut-off of the
The valves
high-pressure cylinder.
vided with
an
are of the piston type pro-
A
inefficient ring packing.
jet
condenser
is
by an independent air-pump driven with steam
The quantity thus used was
taken from the engine pipe.
determined by an independent test and allowed" for. Steam is
supplied from vertical water- tube boilers, and a separator placed
in the steam pipe secured what was believed to be commercially
dry steam without superheating. The valves and pistons all
The load consisted of dynamos
leaked a considerable amount.
used, operated
furnishing current for electric lighting.
With
the exception
cylinder and the valves, this engine is
same as No. 35. During the interval between the tests the
engine had been provided with new valves fitted with packing
and a complete new low-pressure cylinder of larger size.
Referring to the test on Engine No. 35, the figures given here
show an improvement, due largely to a better distribution of
the steam, which was accomplislied by a change of proportion
of the low-pressure
the
in the
The
steam cylinders.
increase in the size of the low-
pressure cylinder enabled this cylinder to do a larger proportion
The reduction
consumed per horse power per
and the reduction in the steam
hour amounted to 18.3%
the
diagrams
at cut-off, which is 17.59^, furfor
accounted
by
of
the work, with corresponding advantage.
in the quantity of feed water
;
nishes a reason for the change.
In view of the leakage of the
not surprising that the proportion of
valves and pistons,
it
is
steam accounted for
is
low
;
and
this is true in the case of both
engines.
To make
a ready comparison of the diagrams in the
two
cases imder consideration, showing the general effect of the
change of cylinders, diagrams from Engine No. 35, taken with
the same load, are superposed in dotted lines upon those relating to No. 39, which are represented in full
lines.
J
ENGINE
No. 39
120-
100-
H.P.
Head End
806040200-
120-
iOO-]
8060-
4020o-J
L.P.
Head End
20
L.P.
Crank End
10
10
ENGINE
No. 40.
Compound Condensing Engine.
Kind
H. P.
L. P.
CVLINDER.
CYLIXDER
of engine
Single valve
Number
of cylinders
Diameter of cylinders
Stroke of piston
.
1
1
30
ins.
18
16
%
33
.
ins.
Clearance
H. F. constant for 1 lb. m. e. p. one revolution per min
Ratio of areas of cylinders
Condition of valves and pistons regarding
leakage
H.P.
16
9
.0103
1
Practically
tight
Data and Results of Feed - Water
.0285
2.78
Practically
tiirht
Test.
Character of steam
Ordinary
Duration
Weight
1.62'
of feed-water
consumed
Feed-water consumed per hour
Pressure in steam pipe above atmosphere
Vacuum in condenser
Revolutions per minute
Mean
Mean
hrs.
0.
660
(J,
326.1
lbs.
126
lbs.
lbs.
21.1
ins.
228
H. P. cylinder
63.9
lbs.
effective pressure, L. P. cylinder
30.4
lbs.
Indicated horse-power, H. P. cylinder
149.7
Indicated horse-power, L. P. cylinder
197.9
Indicated horse-power, whole engine
347.6
H.P.
H.P.
H.P.
18.2
lbs.
effective pressure,
Feed-water consumed per
I.
H. P. per hour
Measurements based on Sample Diagrams.
Initial
pressure above atmosphere
Cut-off pressure above zero
.
.
....
....
Release pressure above zero
Mean effective pressure
Back pressure at mid stroke, above or
below atmosphere
Proportion of stroke completed at cut-off
Steam accounted for at cut-off
Steam accounted for at release
Proportion of feed-water accounted for
L. P.
Cylinder.
lbs.
111.6
114.8
82.4
63.4
lbs.
+ 24.5
lbs.
lbs.
lbs.
.
.
.
lbs.
.
.
.
lbs.
at cut-off
H. P.
CVLIXUEK.
49
29.7
25.7
30.1
-7.
.596
16.58
15.59
.795
17.58
16.11
.911
.mb
.857
.885
Proportion of feed-water accounted for
at release
158
ENGINE
Engine No. 40
159
No. 40.
a vertical single-acting engine with unjack-
is
eted cylinders and a single piston valve fitted with ring packing, one
valve
apparatus
steam.
is
serving for both
cylinders.
The condensing
a surface condenser with air-pump operated
During the
test the
by
exhaust from the air-pump escaped
pump was
to the atmosphere.
This
a proper vacuum.
Steam is furnished by horizontal return
was found by calorimeter test that at a
tubular boilers.
It
point near the engine
The
it
of insufficient size to give
contained one-half of
1%
of moisture.
pistons and the valve were practically tight, although in
this class of engines there is
always some escape of water by
the piston rings into the crank case.
centrifugal
The
The load consisted
of a
pump.
feed- water
was measured by collecting the water
charged from the surface condenser.
The quantity thus
dis-
deter-
mined does not include that referred to above, which leaked
from the steam cylinders into the crank case, and which there is
no ready means of determining.
The consumption of feed-water here given was less than the
actual amount of steam which passed through the engine,
owing to the fact above noted that some of the steam which
was condensed in the cylinders passed into the crank case and
failed to be measured.
This accounts for the large proportions
which the steam accounted for at cut-off and release bears to
the feed-water consumption.
In view of the late cut-off, the
high back pressure in the small cylinder, the excellent quality
of the steam furnished to the engine,
valve,
all
of
which tend
to reduce
and the tightness of the
the losses shown by an
must necessarily be
The leakage referred to could hardly be expected to
exceed 5%. Assuming it to be 5%, the feed- water consumpanalysis of the diagram, these proportions
large.
would stand 19.1
lbs., and the proportions of steam accounted for at cut-off in the two cylinders .87 and .92 respect-
tion
ively.
ENGINE
No.
40
H.P. Cyl.
100
80
60
40
20
-
UP.
Cyl.
40
20
.
ENGINE
No. 41
Compound Condensing Engine.
H. P.
L. P.
Cylinder.
Cylinder.
Kind
Single valve
of engine
of cylinders
Diameter of cylinder
Diameter of piston rod
Stroke of piston
Number
1
m
1
ins.
lu
ins.
2
13
ins.
Clearance
%
H. r. constant for one lb. m. e. p. one
H.P.
revolution per minute
Ratio of areas of cylinders
ins.
Inside diameter of steam pipe
ins.
Inside diameter of exhaust pipe
Condition of valves and pistons regarding leakage
.
.
.
7
.
.
.
.
4
2.61
5
5
7
1
Considerable
leakage
Data and Results of Feed -Water
Tests.
Test.
A.
B.
Character of Load.
Light Load.
Heavy Load.
Ordinary
Ordinary
Character of steam
Duration
hrs.
Weight of feecl-water consumed.
Feed-water consumed per hour
Pressure in steam pipe above atmos.
Vacuum in condenser
Revolutions per minute
Mean effective pressure, H. ]'. cylinder
.
.
.
.
lbs.
,
lbs.
lbs.
ins.
Mean effective pressure, L. P. cylinder
Indicated horse-power, H. P. cylinder
lbs.
lbs.
H.P.
Indicated horse-power, L. P. cylinder H.P.
horse-power,
whole
Indicated
engine
H.P.
Feed-water consumed per I H. P. per hr
lbs
.
.
.
3.5
7,203.5
2,058
129.7
25.9
306
25.02
7.27
51.5
39.
90.5
22.74
Measurements based on Sample Diagrams, heavy load
H.P.
Cylinder.
Tkst.
pressure above atmosphere
Corresponding steam-pipe or receiver
Initial
.
pressure
Cut-off pressure above zero
Release pressure above zero
Mean
.01755
.00672
.
....
.
2
13
10
.
....
....
effective pressure
Back pressure
at
4.8
18,043.
3,759
130.1
25.5
298.5
48.5
19
97.3
99.5
196.8
19.1
Test.
L. P.
Cylinder.
lbs.
130
20.3
lbs.
132
115.2
24.6
lbs.
lbs.
63.1
48.9
lbs.
+ 20.3
lbs.
15.
19.2
mid stroke above or
below atmosphere
Proportion of stroke completed at cut-off
Steam accounted for at cut-off
Steam accounted for at release
Proportion of feed-water accounted for
.382
.
.
.
lbs.
.
.
.
lbs.
at cut-off
Proportion of feed-w. acc'd for at release
161
12.03
13.43
.629
.703
-11.1
.409
9.97
12.76
.522
.668
ENGINE
162
TESTS.
Engine No. 41 is a vertical cross-compound unjacketed highspeed engine, having unpacked piston valves, one for each
cylinder,
and controlled by a shaft governor operating on the
cut-off of the high-pressure cylinder.
A
jet
condenser
is
used,
operated by an independent air-pump driven by steam taken
from the main
The quantity
pipe.
of steam used
by the con-
denser was determined by an independent test and allowed
for.
Allowance was also made for steam condensed in the large service main, which was designed for supplying several other
engines besides the one tested.
Steam was furnished by horishowed that
zontal return tubular boilers, and a calorimeter test
it
contained j% of
1%
of moisture.
The valve
pressure cylinder was found to leak quite badly.
low-pressure cylinder was reasonably tight.
of the high-
That
of the
The leakage
of
the valves interfered "with a determination of the condition of
the pistons.
The load consisted of dynamos furnishing curThe tests were made with two differ-
rent for electric lighting.
ent loads, other conditions remaining the same.
If the results of this test are
compared with those made on
a four- valve engine such as No. 36, which showed a
much more
economical performance, the effect of various features in the
Engine No. 41 had a single
valve, which secured less perfect distribution of steam than the
It had larger percentages of
four valves of the other engine.
design of the engine are apparent.
clearance space, and finally, the type of valve used permitted a
much
larger
engine.
amount
rapid reciprocations
effect to
of leakage
than occurred in the other
Engine No. 41, however, had the advantage of more
;
but
this, it
appears, did not have sufficient
overcome the losses due to the causes mentioned.
ENGINE No. 4.1a
120100-
8060-
40-
20'
0-
I20-,
100-
80-
6040-
20
o--
L.P.
Top
5-|
0510-
L.P.
5-|
05loJ
Bottom
ENGINE No. 4-lb
120
100-
806040
20
120-
100
H.P.
80
60-
4020
0-J
L.P.
L.P.
20
10-
010-
Top
Bottom
Bottom
ENGINE
No. 42.
Compound Non-Condensing Engine.
H.P.
Cylinder.
Kind
of engine
of cylinders
Diameter of cylinders
Diameter of piston rod
Stroke of piston
Number
L. P.
Cylinder.
Single valve
....
....
1
1
ins.
lU
ins.
2
13
18^
2
13
7
10
ins.
%
Clearance
H. P. Constant for one lb. m. e. p.
H.P.
one rev. per min
Ratio of areas of cylinders
Condition of valves and pistons
regarding leakage
.
.
....
.01755
2.61
.00672
1
.
Considerable
leakage
Data and Results of Feed -Water
Tests.
Test.
A.
Conditions regarding Load.
Light Load.
Heavy Load.
Character of steam
Duration
hrs.
lbs.
Weight of feed-water consumed
lbs.
Feed-water consumed per hour
Press, in steam pipe above atmos. lbs.
Revolutions per minute
Mean effective pressure, H.P. cyl. lbs.
Mean effective pressure, L.P. cyl. lbs.
Indicated horse-power, H. P. cyl. H.P.
Indicated horse-power, L. P. cyl. H.P.
H.P.
Indicated H. P., whole engine
Feed-water cons, per I. H. P. per hr. lbs.
Ordinary
Ordinary
.
.
....
B.
5
10,228
2,045.6
126.5
300.2
20.36
15,369
3,842.2
128
292.7
42.16
13.56
82.89
69.59
152.48
25.2
.86
41.05
4.53
45.58
44.89
.
Measurements has ed on Sample Diagrams.
Test,
H.P.Cyl. L.P. Cyl. H.P.Cyl. L.P. Cyl.
Conditions regarding Load.
Initial pressure above atmosphere
Corresponding steam-pipe or re-
lbs.
ceiver pressure
Cut-off pressure above zero
Release pressure above zero
Mean effective pressure
Back pressure at mid stroke above
.
lbs.
125.
.
.
lbs.
112.4
.
.
lbs.
40 9
.
.
lbs.
20.2
lbs.
10.7
.
lbs.
.
lbs.
.107
10.21
26.43
atmosphere
Proportion
of
at cut-off
10.3
120
30
128.
19.5
.7
1.
120.3
64.7
42.27
29.9
53.5
20.6
14.1
1.8
stroke completed
Steam accounted
Steam accounted
Proportion
ed for
Proportion
ed for
116.4
for at cut-off
for at release
of feed-water accountat cut-off
of feed-water accountat release
....
....
.228
.589
165
.526
28.26
.629
.389
15.56
17.16
.424
13.82
16.66
.617
.548
.681
.661
;
ENGINE
166
Engine No. 42
is
TESTS.
of the vertical
cross-compound unjacketed
of Engine No. 41, being
power house, and forming a pait of the
same plant. It was supplied with steam from a different portion of the service main, the water condensed in which returned
back to the boiler. Unlike engine No. 41 it was run non-conThe valves and pistons leaked to about the same
densing.
extent as in the other engine, and the load Avas of the same
The tests were two in number, one being made
character.
high-speed
class.
It is a duplicate
located in the same
with a very light load.
These
tests bring
out very forcibly the wastefulness of a non-
condensing compound engine of this type when carrying an
extremely light load.
In the case of the
first test
the load was
so small that the low-pressure cylinder contiibuted only about
10% of the whole power, which is so small as to be immaterial
and consequently, the engine showed simply the economy due
to a non-condensing cylinder of this type carrying a high back
pressure, and working at a comparatively early cut-off.
The
effect of valve leakage is revealed by the small proportion of
steam accounted for by the indicator. Compared with the condensing engine of the same type, No. 41, there is a marked
advantage due to the use of the condenser and this appears to
Comparing the
be especially true in the case of the light load.
two heavy-load tests the reduced consumption of feed-water is
;
6.1 lbs. per
I.
H. P. per hour, or about 24 «y^.
test there is a remarka])le increase in the
In the hght-load
steam accounted for
at release of the high-pressure cylinder over that
off.
It is
due largely no doubt
to valve leakage.
shown
at cut^
ENGINE No. 4.2a
-120
-100
-80
-60
-40
-20
I-
-120
-100
80
-
H.P. Bottom
-60
-40
-20
-
30
20
10
-
L.P.
Bottom
20
10
ENGINE No. 42b
-120
H.P.Top
-100
/
-80
-60
-40
.^
-20
^
H.P.
Bottom
^
Ml
pl20
-100
/
^
-80
-60
-40
-20
-
L.P.
Top
30
L.P.
Bottom
20
10
ENGINE
No. 43.
Compound Condensing Engine.
H.P, Cylindek.
Four valve
Kind
of engine
of cylinders
Diameter of cylinder
Diameter of piston rod
Stroke of piston
Number
ins.
1
48.3
6
.
12
Fairly tight
Data and Results of Feed -Water
Fairly tight
Test.
Character of steam
Duration
Weight of feed-water consumed
Feed-water consumed per hour
Pressure in steam pipe above atmosphere
Pressure in receiver above atmosphere
Vacuum in condenser
Kevolutions per minute
Mean effective pressure H. P. cylinder
Mean
.556
3.04
1
.
.
5
2.5
.1828
....
(Corliss)
27.9
5
2.5
ft.
Cylindek.
1
ins.
%
Clearance (assumed)
H. P. constant for one lb. m. e. p. one
H.P.
rev. per min
Ratio of areas of cylinders
ins.
Inside diameter of steam pipe
Condition of valves and pistons regarding leakage
L.P.
Superh'd 44.5 degs.
19.08
257,351
13,488
119.8
hrs.
11.0
25.7
70.03
39.04
13.28
499.9
517.2
1,017.1
13.26
lbs.
effective pressure L. P. cylinder
Indicated horse-power H. P. cylinder
Indicated hor.se-power L. P. cylinder
Indicated horse-power, whole engine
Feed-water consumed per I. H. P. per hour
lbs.
lbs.
lbs.
ins.
lbs.
lbs..
H.P.
H.P.
H.P.
lbs.
Measurements Based on Sample Diagrams.
H. P.
Cylinder.
above atmosphere
Corresponding steam-pipe or receiver press,
Cut-off pressure above zero
Release pressure above zero
lbs.
Mean
lbs.
Initial pressure
.
.
.
effective pres.sure
Back pressure
at
mid
lbs.
lbs.
lbs.
L.P.
Cylinder.
109
113
12.9
114.8
31.4
40.03
22.1
7.4
13.21
stroke, above or be-
low atmosphere
lbs.
Proportion of stroke completed at cut-off
Steam accounted for at cut-off
Steam accounted for at release
Proportion of feed-water accounted for at
.
....
....
lbs.
lbs.
cut-off
+
16.
.236
10.1
12.0
-12.2
.312
9.39
10.21
.762
.708
.908
.77
Proportion of feed-water accounted for at
release
109
ENGINE
170
Engine No. 43
is
TESTS.
a horizontal cross
cylinders and unjacketed
receiver.
compound with jacketed
It
exhausts into a jet con-
denser provided with a direct connected air-pump.
space of either cylinder, which
is
cylinder, forms a thoroughfare through
by
which superheat.
Steam
traps.
jacket
which the steam passes
to the top chest, the steam entering at the bottom.
are drained
The
confined to the barrel of the
is
The valves and
The spaces
supplied by vertical
boilers
pistons of the H. P. cylin-
der leaked a small amount, but those of the L. P. cylinder were
practically tight.
The
dent
A
The
load consisted of cotton machinery.
test reported is the collective result of four indepen-
trials of 4.5 to
5 hours each.
noticeable feature in these results
is
the increase in the
steam accounted for at release H. P. cylinder over that shown
at cut-off, viz., .146.
In working out these figures the clear-
ance was assumed at 2^ %.
1
%
more
(i. e.,
this is notable.
3.5
%)
If
the clearance were in reality
the increase
is
reduced to .123.
Even
ENGINE No. 43
100
80
H.P.
Head End
60
40
20
100
80
H.P.
Crank End
60
40
20
L.P.
L.P.
Head End
Crank End
ENGINE
No. 44.
Compound Non-Condensing Engine.
H.P.
Cylinder.
Kind
of engine
of cylinders
Diameter of cylinder
Stroke of piston
Single valve
,
Number
1
ins.
ft.
Clearance
%
H. P. constant for 1 lb. m. e. p. one
H.P.
revolution per minute
Ratio of areas of cylinders
ius.
Inside diameter of steam pipe
Condition of valves and pistons regarding leakage
.
.
.
11
11
.
11
9
.00264
.
1.
Practically
Practically
tight
tight
Data and Results of Feed- Water
Test.
Character of steam
Duration
Weight of feed-water consumed
Feed-water consumed per hour
Pressure in steam pipe above atmosphere
Revolutions per minute
Ordinary
5.33
13,397
2,511.8
135.9
hrs.
lbs.
lbs.
lbs.
29(5.3
P. cylinder
effective pressure, L. P. cylinder
Indicated horse-power, H. P. cylinder
Indicated horse-power, L. P. cylinder
effective pressure,
.00788
2.98
6
.
.
19
33
....
Mean
Mean
L. p.
Cylixder.
67.2
23.3
53.6
56
109.66
22.91
II.
Indicated horse-power, whole engine
Feed-water consumed per I. H. P. per hour
lbs.
lbs.
H.P.
H.P.
H.P.
lbs.
Measurements based on Sample Diagrams.
H.P.
Cylinder.
pressure above atmosphere
Corresponding steam-pipe pressure
Cut-off pressure above zero
Release pressure above zero
Initial
.
.
lbs.
.
lbs.
....
....
Mean
effective pressure
Back pressure
lbs.
lbs.
lbs.
atmosphere
Proportion of stroke completed at cut-
lbs.
30
.605
18.39
18.56
off
for at cut-off
for at release
65
35.5
28.4
23.6
above
at lowest point
Steam accounted
Steam accounted
130
132
128.2
89.5
67.1
L. p.
Cylinder.
.
.
.
lbs.
.
.
.
lbs.
.662
14.96
16.61
Proportion of feed-water accounted for
at cut-off
.803
.653
.81
.725
Proportion of feed-water accounted for
at release
172
ENGINE
Engine No. 44
is
173
No. 44.
a vertical cross-compound, single-acting,
unjacketed, high-speed engine, having a single
fitted
piston
valve
with ring packing, the speed being controlled by a shaft
Steam is suppUed by a horizontal return tubular
which by calorimeter test contained some 2% of moistDrip pockets in the main pipe and at the throttle valve,
governor.
boiler,
ture.
which were trapped, intercepted most of the entrained water
which would otherwise have passed into the engine. The load
consisted of an electric generator with constant output.
The
valve and pistons were very nearly tight.
ENGINE No. 44
H.P. Cyl.
120100
80
6040-
20
0-"
60
L.P. Cyl
-40
-20
ENGINE
No. 45.
Compound Condensing Engine.
H. P. Cylixdkk. L, p. Cylixdeu
Kind
Double valve
of engine
of cylinders
Diameter of cylinder
Diameter of piston rod
Stroke of piston
Number
'
28
ins.
14
21
ins.
24
24
ins.
Clearance
%
H.P. constant for one lb. m.e.p. one
H.P.
revolution per minute
Ratio of areas of cylinders
Condition of valves and pistons regardin«r leakage
Data and
liesults
.01839
.07436
4.04
Considerable leakage
A.
C.
Ordinary Ordinary Ordinary
Character of steam
Duration
hrs.
Weight of feed-water consumed
Feed-water consumed per hour
.
.
.
lbs.
.
.
lbs.
.
lbs.
Pressure in steam-pipe above atmos.
in receiver
in condenser
lbs.
ins.
Revolutions per minute
Mean
Mean
6.4
of Feed -Water Tests.
TE8T.
Vacuum
2i
3.6
....
....
Pressme
1
1
H. P. cylinder
lbs.
effective pressure, L. P. cylinder
lbs.
effective pressure,
Indicated horse-power, H. P. cylinder H.P.
Indicated horse-power, L. P. cylinder H.P.
H.P.
Indicated horse-power, whole engine
Feed-water consumed per I. H. P. per
.
lbs.
hoiu-
4
19,014
4,753.7
119.9
4
16,366
3,841.6
120,4
10.1
4.5
25.1
25.5
161.75
162.75
67.4
49.97
10.39
7.85
170.74
149.66
124.97
95
296.71
244.65
16.07
3
6,375
2,125
117.6
below
at.
25.6
170.1
25.89
3.35
80.98
42.41
123.39
15.71
17.22
Measurements based on Sample Diagrams.
A
Test.
H.P.
Initial pressure
above atmosphere
.
.
(J
L.P.
H.P.
L.P.
lbs.
117.4
lbs.
10.5
18.6
119
121.8
7.7
14.1
7.5
3.7
lbs.
120
114.5
42.5
57.95
24.97
3.47
lbs.
+10.9
-11.6
9.6
118
5.1
Corresponding steam-jjipe or receiver
pressm-e
Cut-off pressure above zero
Release pressure above zero
Mean effective pressure
Back pressure at mid stroke above or
....
....
below atmospere
Proportion of stroke completed at cut-
lbs.
lbs.
off
Steam accounted for
Steam accounted for
at cut-off
at release
.
.
.
lbs.
.
.
.
lbs.
10.37
-.3.6
-12.4
.336
12.08
12.75
.338
9.06
10.69
.044
6.21
11.32
.761
.563
.361
.503
.793
.665!
.657
.744
..3.36
8.67
12.82
Proportion of feed-water accounted for
at cut-off
Proportion of feed-water accounted for
at release
174
ENGINE
ENGINE
No. 45
175
No. 40.
(Continued).
Data and Results of Feed- Water
Tests.
E.
D.
NOKCOXDEXSIXG.
Ordinary
Ordinary
3
13,356.5
4,452.2
118.9
3
18,614
6,204.7
118
27.8
Test.
Character of steam
hrs.
Dui-ation
Weight
of feed-water
consumed
.
.
lbs.
lbs.
Feed-water consumed per hour
Pressure in steam pipe above atmos. lbs.
Pressure in receiver above atmosphere lbs.
ins.
Vacuum in condenser
K evolutions per minute
Mean effective pressure, H. P. cylinder lbs.
Mean effective pressure. L. P. cylinder lbs.
Indicated horse-power, H. P. cylinder H.P.
Indicated horse-power, L. P. cylinder H.P.
H.P.
Indicated horse-power, whole engine
Feed-water consumed per I. H. P. per hr. lbs.
.
.
.
14.125.8
164.77
46.94
10.99
142.23
134.65
276.88
16.07
.
165.66
52.4
8.81
158.54
108.47
267.1
23.24
Measurements based on Sample Diagrams.
E.
D.
Test.
NonCondensing.
Condensing.
H.P.Cy L.P.Cy. H.P.Cy.
pressure above atmosphere
Corresponding steam-pipe or receiver
pressure
Cut-off pressure above zero
Release pressure above zero
Mean effective pressure
Back pressure at mid stroke above or
Initial
.
.
....
....
below atmosphere
lbs.
lbs.
lbs.
Cy
14.1
113.1
27.8
118
14.5
22.2
7.0
11.07
115
110.8
28.5
31.9
14.9
8.77
-12.2
+28.7
113.1
38.3
47.65
lbs.
lbs.
L.P.
117.6
-H16.
58.2
50.94
+1.2
Proportion of stroke completed at cut.3
off
Steam accounted
Steam accounted
for at cut-off
for at release
.
.
.
lbs.
.
.
.
lbs.
11.16
12.06
.239
8.82
10.71
.487
18.46
19.1
.406
15.83
18.3
Proportion of feed-water accounted for
at cut-off
.548
.794
.681
.666
.821
.787
Proportion of feed-water accounted for
^50
at release
Engine No. 45
is
a horizontal cross-compound with unjack-
eted cylinders and unjacketed receiver.
There
ernor operating on the cut-off of the
H. P. cylinder.
The
cut-off valve rides
on a
main valves
are balanced slides.
seat in the interior of the
The engine exhausts
The
main valve, which
is
is
of
a shaft gov-
box pattern.
into a surface condenser, with indepen-
dent air-pumps, the latter exhausting to waste.
The feed-water
ENGINE
176
TESTS.
consumption was found by weighing the water discharged by
Steam was drawn from the main service of a
the air-pump.
large plant,
dry.
and a calorimeter
The main
test
showed that
it
was
practically
valve of the H. P. cylinder leaked quite badly.
The other valves and pistons leaked a small amount. The
A
engine supplied power to dynamos for electric lighting.
series of tests was made with different loads, and in one case
the engine was run non-condensing.
Considering the wide changes of load in the tests A, B, and
C,
viz.,
from 295. H. P. to 123. H.
P., the
small difference in
economy, 15.71 to 17.22, is noteworthy. Probably the leakage
of the valves of the H. P. cylinder affected the matter, but to
what extent can only be conjectured. The economy is at best
much below that obtained from some of the four-valve engines,
and excessive leakage is the only thing which satisfactorily
The results of tests D and E, condensing and
explains it.
non-condensing, are respectively 16.07 lbs. and 23.24 lbs., from
which
it
appears that the consumption
ing was 30.9% less than
when running condens-
when running non-condensing.
i
ENGINE No. 45a
-120
-100
H.P.
Head End
-
80
-
60
-
40
-
20
-
-120
-100
H.P.
Crank End
-
80
-
60
-
40
-
20
-
L.P.
Head End
L.P.
Crank End
ENGINE No. 45c
-120
-100
-80
H.P.
Head End
-60
-40
-20
-
-120
100
-80
-60
H.P.
Crank End
-40
-
20
-
L.P.
L.P.
Head End
Crank End
r
°
-
5
-
10
-
15
ENGINE No.45d
-120
-100
H.P.
Head End
-80
-60
-40
-20
-
-120
-100
H.P.
Crank End
-80
-60
-40
-20
-
15
10
5
6
10
[5
10
L.P.
Crank End
5
O
6
10
ENGINE
No.
45e
-120
-100
H.P.
Head End
-80
-60
-40
h20
-120
-JOO
H.P.
Crank End
-80
-60
40
-20
-
L.P.
Head End
I-
ENGINE
No. 46.
Compound Non-Condensing Engine.
H. P.
L. P.
Cylinder.
Cylinder.
Four valve
Kind
of engine
of cylinders
Diameter of cylinders
Diameter of piston rod
Stroke of piston
Number
1
....
.
.
.
.
Clearance
H. P. Constant for one lb. m. e.p.
one rev. per min
Ratio of areas of cylinders
Inside diameter of steam pipe
Inside diameter of exhaust pipe
Condition of valves and pistons
regarding leakage
.
1
28
ins.
17.5
31
ins.
48
48
ins.
%
31
4.1
H.P
.0572
.148
2.587
.
.
.
.
ins.
.
ins.
12
....
Practically tight
Data and Results of Feed - Water
Tests.
Test.
A.
B.
Character of steam
Duration
hrs.
Weight of feed-water consumed
lbs.
Feed-water consumed per hour
lbs.
Press, in .steam pipe above atmos. lbs.
Pre.s.sure in receiver above atmos.
Hevolutions per minute
Mean effective pressure, H.P. cyl. lbs.
Mean effective pressure, L.P. cyl. lbs.
Indicated horse-power, H. P. cyl. H.P.
Indicated hor.se-power, L. P. cyl. H.P.
Indicated H. P., whole engine
H.P.
Feed-water cons, per I. H.P. per hr. lbs.
Ordinary
Ordinary
.
8.55
65,501
7,671.2
.
128.7
27.2
101.02
.
.
.
.
34.83
9.75
201.3
.145.6
346.0
22.11
.
Measurements based on
7.87
82,607
10,507.9
135.5
20.5
90.00
52.42
14.19
278.84
207.85
^'aiiple
486 69
21.50
Diagrams.
H.P.CVL. L.P.CvL. H.P.Cyl. L.P. Cyl.
Initial
pressure above atmosphere
Corresponding
steam-pipe
sure
Cut-off pres.sure above zero
Relea.se pre.ssure above zero
Mean
effective pres.sure
Back pressure
at
.
of
at cut-off
28.01
lbs.
34.31
13.88
9.66
116.52
51.76
49.03
34.91
18.26
14.22
2.2
34.3
2.9
125.3
30.3
.
lbs.
.
.
lbs.
.
.
lbs.
129.2
112.37
39 81
34.66
lbs.
32.0
.
lbs.
.
lbs.
.309
17.83
20.34
.338
15.81
18.61
.419
17.62
18.43
.806
.715
.816
.743
.910
.842
.854
.813
.
136.
mid stroke above
stroke completed
Steam accounted
Steam accounted
Proportion
ed for
Proportion
ed for
118.8
pres-
atmosphere
Proportion
lbs.
for at cut-off
for at release
of feed-water accountat cut-off
of feed-water accountat relea.se
....
....
181
.474
16.03
17.54
ENGINE
182
TESTS.
Engine No. 46 is a cross-compound, with horizontal unjackThe valves are all
eted cylinders and unjacketed receiver.
The steam was drawn from horizontal water-tube
plain slides.
boilers,
and contained 0.7
%
of moisture
by calorimeter
The load was miscellaneous iron-working machinery.
were made with two different loads. The valves and
were
all in
pistons
excellent condition as regards leakage.
It is evident
that the
test.
Tests
from an analysis
economy was
as
of the diagrams in these tests,
high as could be expected under the
conditions of boiler pressure, ratio of cylinder areas, and cutoff.
For higher economy a higher pressure, larger
cylinder area, and earlier cut-off are required.
noted, however, that the distribution
and there
is
is
It
ratio of
must
l>e
not the most perfect,
rather a high back pressure in the L. P. cylinder.
ENGINE No. 46a
-120
-100
H.P.
Head End
-80
-60
-40
-20
-
-120
-100
H.P. Crank End
-80
-60
-40
-20
-
30-
20-
L.P.
Head End
10-
30-1
20-
lOH
0-
L.P.
Crank End
ENGINE No. 46b
1-120
H.P.
Head End
-80
40
r-l20
H.P. Crank End
80
40
>-
30-1
L.P.
Head End
20-
10-
30-
L.P.
20-
10-
0-
Crank End
ENGINE
No. 47.
Compound Condensing Engine.
H.P. Cylinder.
Kind
L.P.
Cylinder.
Four valve
of engine
of cylinders
Diameter of cylinder
ins.
Diameter of piston rod
ins.
Number
1
1
183^5
one
Stroke of piston
ft.
%
Clearance
H. P. constant for one lb. m. e. p. one
rev. per min
H.P.
Ratio of areas of cylinders
Inside diameter of steam pipe
ins.
Inside diameter of exhaust pipe
ins.
Condition of valves and pistons regardins; leakage
....
.
Data and
.
.
.
.
liesults
4iV
41
1.8
.08728
.5584
6.398
14
16
1
8
9
ractically
tight
Considerable
leakage
of Feed -Water Tests.
A.
Test.
Conditions regarding use of jackets.
Character of steam
Duration
Weight of dry steam consumed
Dry steam consumed per hour
Pressure in steam pipe above
atmosphere
Pressure
in
receiver
above
atmosphere
Vacuum in condenser
Revolutions per minute
44i^5
Jackets
OFF.
C.
13.
D.
Jackets Jackets Jackets
I
ON.
ON.
ON.
Ordinary
hrs.
.
lbs.
.
lbs.
4.833
4.817
42,147.
8,749.8
823.3
8,596.6
150.7
151.1
150.5
lbs.
643.
151.4
00.31
9.4
27.3
60.54
60.59
19.4
28.0
60.33
lbs.
67.79
66.15
59.9
57.13
cylinder
lbs.
Indicated horse-power, H. P.
cylinder
H.P.
Indicated horse-power, L. P.
cylinder
H.P.
Indicated horse-power, whole
engine
H.P.
Dry steam consumed per I. PI. P.
per hr
lbs.
9.87
10.63
10.78
11.39
360.8
349.52
316.77
300.85
332.52
359.31
364.69
383.71
689.32
708.33
681.45
684.56
12.45
12.61
12.72
....
.
Mean
effective pressure,
.
II.
effective pressure,
10.6
27.
.
P.
cylinder
Mean
lbs.
ins.
15.0
27.1
^707.
L. P.
.
186
12.69
ENGINE
186
TESTS.
Measurements Based on Sample Diaarams.
A.
Te.st.
above atmospliere
Corresponding steam-pipe or re-
lbs.
ceiver pressure
Cut-off pressure above zero
lbs.
Initial pressure
.
.
Release pressure above zero
effective pressure
Back pressure at mid stroke,
above or below atmosphere
Proportion of stroke completed
Mean
.
lbs.
.
.
lbs.
.
.
lbs.
.
lbs.
H.P.Cyl.
145.2
150.
149.2
42.5
68.19
+10.9
.281
at cut-off
Steam accounted
Steam accounted
for at cut-off
for at release
feed-water ac.
at cut-off
feed-water acat release
Proportion of
counted for
Proportion of
counted for
.
jacketed cylinders
is
.
lbs.
.
lbs.
10.00
10.34
.
.
Engine No. 47
Engine No. ^7
a
.
horizontal
and a reheater.
B.
L.P. Cyl. H.P.Cyl. L.P.Cyl.
9.8
146.1
10.6
149.2
149.3
20.
5.3
9.78
and barrel
superheat the
some
of
that
66.06
-12.6
+10.1
.25
.263
9.22
9.59
8.69
9.54
.282
9.13
9.61
.788
.685
.740
.733
.815
.752
.770
.771
tandem compound, with
The condenser is of the
The
of the H. P. cylinder,
heads but not the barrel of the L. P. cylinder.
of the tubular type,
95
18.9
5.4
10.55
41.
-12.1
siphon type with water supplied by gravity.
applies to heads
9.
The
jacketing
and
to the
reheater
is
and contains a sufficient area of surface to
steam passing to the L. P. cylinder, although
entering
the
heater remains
in
a
condensed
drawn off by a trap. The valves are all of the
gridiron type.
The steam is furnished by horizontal tubular
boilers, and it was found by calorimeter test to be practically
dry.
The valves and piston of the H. P. cylinder were found
in good condition.
The steam valve at the head end of the
L. P. cylinder leaked badly, and the crank-end valve a considerable amount; but as near as could be judged under these
circumstances the exhaust valves and piston were fairly tight.
The load was cotton machinery. Three tests were made with
different receiver pressures, and one test was made with
and
state,
steam shut
On
test
off
B
from jackets and reheater.
the water condensed in the jackets and reheater
amounted
tubes
This
is
is
to
681
lbs.
per hour, or 7.7% of the
included in the total quantity given in the table.
total.
I
ENGINE
A
noticeable feature of
crease in
the
187
No. 47.
these results
is
the systematic in-
steam consumption per H. P. per hour as the
receiver pressure was raised.
This
may have been due
to the
increased leakage of the L. P. steam valves.
A
due to the
2%. Although
this is not a marked difference, it is evident from an analysis
of the diagrams that the jackets had a considerable effect upon
comparison of the jacket
tests reveals a gain
jackets of 0.24 lbs. per H. P. per hour, or about
the
distribution
of
the
steam,
especially
in
increasing
power developed by the L. P. cylinder and the quantity
steam accounted for by the diagram for that cylinder.
the
of
ENGINE No. 4-7a
140
h-120
H.P.
Head End
100
80
60
-40
20
-
140
-120
H.P.
Crank End
100
h
80
60
-40
-20
-
L.P.
L.P,
Head End
Crank End
10
5
5
10
ENGINE No. 47b
-140
-120
H.P.
Head End
-100
-80
-60
-40
-20
-
-140
-120
H.P.
Crank End
-100
-80
-60
-40
-20
-
10
L.P.
Head End
5
\-
5
10
L.P.
Crank End
-10
- 5
6
10
ENGINE
No. 48.
Compound Condensing Engine.
H. p.
L. P.
Cylinder.
Cylinder.
Kiud
Four valve
of engine
of cylinders
Diameter of cylinder
Diameter of piston rod
Stroke of piston
Number
1
28A
ins.
6
5
4
ft.
^
Clearance
Horse-pov^rer constant for one lb. m.e.p.
H.P.
one revolution per minute
Ratio of areas of cylinders
Condition of valves and pistons regarding leakage
.
.
itse
of reheater.
Character of steam
Duration
Total weight of feed-water consumed
Total feed-water consumed per hour
Feed-water consumed per hour by air.
6
.682
3.69
Fairly tight
Tests.
B.
Reheater Reheat'b
ON
OFF.
c.
iEA
ON.
Sup'd 12° Sup'd 13° Sup'd 20o
hrs.
lbs.
lbs.
pump
per
7
5
A.
Test.
Feed-water consumed
engine alone
two
1
Data and Results of Feed - Water
Conditions REOARDiNt*
54
.185
.
....
'
1
ins.
5.0
101,466.
20,293.
5.0
97,856.
19,571.2
2,063.
2,030.
1,744.
17,541.2
121.5
19,327.
100.2
10.2
27.4
5.0
105,355.
21,071.
hour by
lbs.
Pressure in steanT pipe above atmos. lbs.
Pressure in receiver above atmosphere lbs.
ins.
Vacuum in condenser
Revolutions per minute
Mean effective pressure, H. P. cylinder lbs.
Mean effective pressure L. P. cylinder lbs.
Indicated horse-power, H. P. cylinder H.P.
Indicated horse-power, L. P. cylinder H.P.
H.P.
Indicated horse-power, whole engine
Total feed-water consumed per I.H. P.
per hour
lbs.
Feed-water per I. H. P. per hour,
eniane alone
lbs.
.
18,230.
125.9
11.4
10.1
27.
27.
46.11
12.08
656.51
634.62
1,291.13
76.69
46.47
11.34
658.90
593.31
1,252.21
1,281.73
15.72
16.63
16.44
14.12
14.01
15.08
77.
* This refers to steam used by the engine aloue.
190
76.68
45.29
12.22
642.16
6.39.57
;
ENGINE
191
No. 48.
Measurements based on
Sam pie Diag rams.
A.
Test.
B.
C.
H.P.CV. L.P.Cy. H.P.Cy. L.P.Cy. H.P.Cy. L.P.Cy.
Initial
pressure above
atmosphere
Corresponding steam
.
.
lbs.
.
119.5
pipe
or receiver
lbs. 127.
pressure
Cut-off pres. above zero lbs. 115.3
Release pres. above zero lbs. 38.2
lbs. 46.62
Mean effective press.
Back pressure at mid
stroke above or be-
....
low atmosphere
lbs.
.
at cut-off
....
Steam accounted
at release
.
113.3
11.8
12.3
121.
22.
112 5
9.8
20.7
37.7
8.3
12.29
.
.326
.294
94.8
10.3
18.8
8.5
12.25
39.
45.11
11.5
-10.7 +13.7
.326
.31
10.
100.
93.
7.7
46.99
—10.7 +16.5
+18.5
Proportion of stroke
completed at cut-off
Steam accounted for
13.1
—11.3
.432
.416
lbs.
11.18
10.66
11.99
10.33
12.41
12.18
lbs.
12.27
11.55
12.63
11.
13.04
12.25
for
.
.
feed
Proportion of
water accounted for
at cut-off
.
.
.
.792
.755
.856
.737
.823
.808
.869
.818
.901
.785
.865
.812
feed
Proportion
of
water accounted for
at release
.
.
Engine No. 48
.
a horizontal
is
cross
compound, with un-
jacketed cylinders and a reheating receiver.
The condenser
plain slides.
is
of
the
jet
The
valves are
type with steam-
driven air-pump, the steam used for which was determined
and allowed
The
for.
boilers are of the vertical fire-tube type,
furnishing slightly superheated steam.
valve of the H.
P
The crank end exhaust
cylinder leaked considerably, but with this
exception the valves and pistons were practically tight.
The
load was cotton machinery.
A
comparison of
tests
A
and C shows the
effect of
two
widely different pressures upon the economy, one being 125.9
and the 'other 100.2 lbs. The reduction of pressure increased the consumption from 14.12 lbs. per I* H. P. per hour
lbs.,
to 15.08 lbs., or nearly 7
Test
B
%.
compared with test A exhibits the effect of
There is a slight loss of economy
the reheater.
as
shutting off
but as the difference
is
within the limits of errors of measure-
ENGINE
192
ment and
be said
accidental difference of condition, the most that can
is
that the
economy produced by the reheater was
this case inappreciable.
per hour condensed
This
the
4
is
%
On
test
and drawn
of the quantity
power developed by the
A
in
there was 648 lbs. of steam
from the reheater tubes.
off
used by the engine.
heat derived from this
amount
TESTS.
source
is
L. P. cylinder,
The
effect of
seen in the increased
and the increase
in the
of steam accounted for in the L. P. cylinder as com-
pared with that in the H. P. cylinder.
The
pump
comparativel}^ large
is
amount
noticeable, being about
on Test A.
10
of
%
steam used by the
air-
of the entire quantity
ENGINE No. 48a
120^
100-
H.P. Cyl.
Head End
80H
6040200-
-120
H.P. Crank
-100
End
80
-
60
40
20
-
UP. Head End
16-
10-
50610-"
L.P.
Crank End
ENGINE No. 48b
120-1
100-
H.P.
80-
Head End
60-
4020-
-120
iOO
H.P. Crank
End
80
60
40
-
-
L.P.
Head End
1510-
50-
510-
L.P.
Crank End
20
ENGINE No.48c
100-1
80-
H.P.
60-
Head End
40200-
-100
H.P.
-
80
-
60
Crank End
-
40
20
L.P.
Head End
10-
L.P.
6H
05lO-J
Crank End
ENGINE
No. 49.
Compound Condensing Engine.
Kind
H. P.
L. P.
Cylinder.
Cylindeb.
Four valve
of engine
Number of
cylinders
Diameter of cylinder
Diameter of piston rod
Stroke of piston
ins.
1
24
44
5^
ins.
ft.
5,
Clearance
%
H. P. constant for 1 lb. m. e. p. one
revolution per minute
H.P.
Ratio of areas of cylinders
Condition of valves and pistons regarding leakage
3
....
....
51
5
4i
.457
.1337
Some
3.43
Fairly
leakage
tight
1
Data and Results of Feed - Water
Test.
Character of steam
Duration
Weight of feed-water consumed
Feed-water consumed per hour
Pressure in steam pipe above atmosphere
Pressure in receiver above atmosphere
Vacuum in condenser
Revolutions per minute
Mean effective pressure, H. P. cylinder
Mean
(Corliss)
1
Ordinary
4.75
58.832
12,385.6
115.4
6.8
28.4
71.3
47.93
12.71
457.9
effective pressure, L. P. cylinder
Indicated horse-power, H. P. cylinder
Indicated horse-power, L. P. cylinder
Indicated horse-power, whole engine
Feed-water consumed per I. H. P. per hour
415
872.9
14.18
hrg.
lbs.
lbs.
lbs.
lbs.
ins.
rev.
lbs.
lbs.
H.P.
H.P.
H.P.
lbs.
Measurements based on Sample Diagrams.
H.P.
CVLINDBB.
pressure above atmosphere
Corresponding steam-pipe and receiver
Initial
.
pressure
Cut-off pressure above zero
Release pressure above zero
Mean
.
....
....
effective pressure
lbs.
100.9
lbs.
114
104.4
36.3
49.03
lbs.
lbs.
lbs.
L. P.
Cylinder.
9.3
10.6
19.
8.6
12.71
Back pressure
at mid stroke above or
below atmosphere
Proportion of stroke completed at cut-
lbs.
off
Steam accounted
Steam accounted
+12.7
.33
for at cut-off
for at release
.
.
.
lbs.
.
.
.
lbs.
12.28
12.95
-11.8
.404
10.82
11.78
Proportion of feed-water accounted for
at cut-off
.806
.763
.913
.831
Proportion of feed-water accounted for
at release
196
ENGINE
Engine No. 49
is
a cross
No. 49.
197
compound
horizontal engine with
jacketed cylinders, and a jet condenser operated by a direct con-
nected air-pump.
The
jacket spaces are of the kind which allow
the steam to pass through them before entering the steam chest
and the water of condensation drains to waste.
Steam is supplied from water-tube boilers through a pipe about
100 feet in length, which is trapped near the throttle valve.
Steam lost by condensation in this pipe, and that used for certain heating purposes, was determined independently, and
The front-end steam valve of the high-pressure
allowed for.
of either cylinder,
cylinder leaked badly.
pistons
With
this exception, the valves
throughout were in fairly good condition.
and
The load
was cotton machinery.
Considering the proportion which
is
borne by the steam
accounted for to the feed-water consumption in the high-pressure cylinder, the result of this test, 14.18 lbs. per.
per hour,
formance.
must be considered
as an
I.
H. P.
exceptionally good per-
ENGINE No.49
rooH
80-
H.P.
Head End
60-
40200-
-100
H.P.
Crank End
— 80
60
40
L.P.
—
20
—
O
Head End
1
L.P.
Crank End
ENGINE
No. 50.
Compound Condensing Engine.
Kind
H. P.
L. P.
Cyli>'dek.
Cylinder
Four valve
of engine
Number
of cylinders
Diameter of cylinders
Diameter of piston rod
Stroke of piston
1
431
ins.
4iJ
5H
ft.
6
%
2.5
6
4
ins.
Clearance
H. P. constant for 1 lb. m. e. p. one revolution per min
Ratio of areas of cylinders
Condition of valves and pistons regarding
leakage
H.P.
.1631
Some
leakage
Data and Results of Feed -Water
Superheated 30°
of feed-water
consumed
Feed-water consumed per hornPressure in steam pipe above atmosphere
Pressure in receiver above atmosphere
in condenser
Revolutions per minute
Mean
Mean
tiffht
Test.
Duration
Vacuum
.5577
3.42
Fairly
1
Character of steam
Weight
(Corliss)
1
5
hrs.
63,003
lbs.
10,600.7
lbs.
108.1
lbs.
13.4
lbs.
27.2
ins.
61.4
H. P. cylinder
35.77
lbs.
effective pressure, L. P. cylinder
12.86
lbs.
effective pressure,
Indicated horse-power, H. P. cylinder
358.2
Indicated horse-power, L. P. cylinder
440.2
Indicated horse-power, whole engine
Feed-water consumed per I. H. P. per hour
798.4
13.28
H.P.
H.P.
H.P.
lbs.
Measurements based on Sample Diagrams.
H.P.
Cylinder.
Initial pressure above atmosphere
Corresponding steam-pipe and receiver
.
pressure
Cut-off pressure above zero
Release pressure above zero
Mean
.
....
....
effective pressure
Back pressm-e
at
mid
lbs.
94.9
lbs.
108
102.6
28.1
35.78
lbs.
lbs.
lbs.
L. P.
Cylinder.
12.8
13.4
22.4
6.9
12.72
stroke, above or
below atmosphere
lbs.
Proportion of stroke completed at cut-off
Steam accounted for at cut-off
Steam accounted for at release
Proportion of feed-water accounted for
.
.
.
lbs.
.
.
.
lbs.
at cut-off
+ 16.3
-12.4
.274
11.81
11.97
10.23
10.87
.889
.77
.901
.819
.27
Proportion of feed-water accounted for
at release
199
ENGINE
200
Engine No. 50
a cross
is
compound engine with
steam jacketed cylinders and a
direct connected air-pump.
TESTS.
jet
The jacket
of the L. P. cylinder
forms a thoroughfare through which the steam
the steam
The
horizontal
condenser operated by a
is
supplied to
steam being admitted through the bottom.
chest, the
The
jacket of the H. P. cylinder drains into the receiver.
drip of the receiver and of the low-pressure jacket passes to a
pump operated by the engine, and thence to flue heaters, or
" regenerators " as they are called, which are located in the flue
of the boilers.
The steam generated
By
in these heaters returns
means the low-pressure cylinder
receives benefit from some of the heat which would otherwise
escape from the boilers to the chimney.
Steam is supplied
from vertical boilers, which superheat. The exact amount of
superheating was not determined; but from the operation of
boilers of similar type, the temperature was probably 30° above
to
the
receiver.
The
the normal.
this
piston of the high-pressure cylinder leaked
considerable, but the piston of the low-pressure cylinder and
the valves of both were in good condition.
The load was
that
of a cotton mill.
The results of this test are interesting on account of
means provided for reheating the steam and re-evaporating
the
the
jacket water for the use of the low-pressure cylinder, employ-
ing for this purpose the heat of the waste gases of the boilers.
Comparing this test with that made on Engine No. 49, where
no such provision was made, the difference is quite marked,
being
.9 of
difficult to
effect
a
pound per
I.
H. P. per hour, or nearly 1%.
determine by this comparison
how much,
was produced by the reheating process, because
difference
in
the condition of
the st^am;
It is
if
any,
of the
and, furthermore,
because there was quite a difference in the degree of expansion,
the cut-off in the high-pressure cylinder of one engine being
.33,
and
The effect of the reheating is not
show in the analysis of the diagrams.
was no more steam accounted for in the
in the other .27.
sufficiently
marked
to
It appears that there
low-pressure cylinder in one case than in the other.
quantity might be expected
duced by the reheating.
if
there
was a marked
A greater
effect pro-
ENGINE No. 50
100-
80-
H.P.
Head End
60H
40200-
-100
-80
H.P.
Crank End
-60
— 40
-20
O
I- 15
L.P.
Head End
10
5
6
10
15
L.P.
Crank End
10
5
h- 5
10
ENGINE
No. 51
Compound Condensing Engine.
...
Kind
of engine
of cylinders
Diameter of cylinder
Diameter of piston rod
Stroke of piston
.
,
,
H. P.
L. P.
Cylinder.
CVLIKDER.
Four valve
,
Number
ins.
....
ins.
ft.
Clearance
%
H. P. constant for one lb. m. e. p. one
revolution per minute
H.P.
Ratio of areas of cylinders
Condition of valves and pistons regarding leakage
.
.
1
1
18
31
4
2
48i
....
JJata
and
llesults
4
2J
.0604
.
.
41
.4412
7.3
1
Some
Some
leakage
leakage
of Feed- Water Test s.
Test.
A.
B.
C.
Character of steam, degs. superh'g
15.7
16.4
12.2
Duration
hrs.
5
6
5
Weight of feed-water consumed
lbs. 41,210
30,583
39,174
P'eed-water consumed per hour
8,242
7,916.6
7,834.8
141). 7
Pressure in steam pipe above atmos.
150.4
150.2
lbs.
6.4
Pressure in receiver
9.1
12.9
Vacuum in condenser
ms.
26.9
26.4
26.6
Revolutions per minute
rev.
80.04
80.14
80
72.44
65.89
Mean effective pressure, H. P. cylinder lbs.
61.9
9.03
Mean effective pressure, L. P. cylinder lbs.
9.59
10.2
350.9
Indicated horse-power, H.P. cylinder. H.P.
318.9
299.3
H.P.
300.6
330.2
Indicated horse-power, L.P. cylinder
359.8
670.5
H.P.
658.1
Indicated horse-power, whole engine
659.1
12.29
12.03
11.89
Feed-water cons, per I. H. P. per hour lbs.
.
.
.
.
.
.
.
Measurements Based on Sample Diagrams.
Test.
A.
H.P.
Initial pressure above atmosphere
Corresp. steam-pipe and receiver pres.
Cut-off pressure above zero
Relea.se pressure above zero
.
.
....
....
Mean
effective pres.sure
Back pressure
at
lbs.
6.2
lbs.
5.5
below atmosphere
at cut-off
Proportion of feed-water
at release
lbs.
.
.
.
lbs.
.
.
.
lbs.
+6
.285
9.54
9.62
150.6
145.9
43.
62.27
14.5
12.8
24.7
6.2
10.23
-13.1
.323
9.07
8.88
+ 16.5 -13
.285
9.21
9.58
.176
7.96
8.43
.77
.732
.769
.654
.776
.710
.8
.704
Not corrected.
— The weight of steam
%
9.08
143.
1
L.P.
accoimted for
*
three trials, 9.5
16.4
5.2
H.P.
mid stroke above or
Proportion of stroke completed at cut-off
Steam accounted for at cut-off
Steam accomited for at release
Proportion of feed-water accounted for
Note.
143.9
151
lbs. 149
lbs. 42.5
lbs.
72.7
c.
L.P.
of the total
condensed in all the jackets averaged, for the
steam consumed
and this is included in the
;
quantities given.
202
ENGINE
203
No. 51.
Engine No. 51 is a horizontal cross compound, with jacketed
The condenser is of the siphon type,
cylinders and a reheater.
and water is supplied by gravity. Both the barrel and the
heads of the high-pressure cylinder are jacketed, but only the
barrel of the L. P. cylinder.
The
reheater has sufficient sur-
face to superheat the steam, although not sufficient to prevent
some water condensing in the bottom of the shell, from which
The jackets are drained by traps
it is drawn away by a trap.
which discharge to waste. The valves are all of the gridiron
Steam is supplied from vertical boilers which supertype.
The piston of the H. P. cylinder was found to show
heat.
The low-pressure exhaust valve at the crank
some leakage.
end leaked quite badly. The piston of the L. P. cylinder and
the remaining valves were in good condition.
Three tests
were made, using three different receiver pressures.
These
of
tests are of interest
volumes
that which
of the cylinders.
is
high-pressure
common
on account of the unusual
This ratio
is
about the same as
practice between the low-pressure
cylinder of
a
triple
ratio
expansion
engine.
and
This
large ratio taken in conjunction ^vith the high initial pressure,
and the fact that the steam was
slightly superheated, furnishes
an explanation for the economical results obtained, which are
unusual.
Comparing the three tests together, it appears that there was
improvement produced by increasing the receiver
a gradual
pressure, the best result being obtained
when
that pressure was
the highest.
In this connection,
sure
increased,
l:)ecame
less,
the
cylinder became
it is
and the
noticeable that as the receiver prescut-off in
the low-pressure cylinder
steam accounted for by the low-pressure
less.
ENGINE No.SIa
140-1
120-
H. P.
100-
Head End
80-
60-
4020-
0-
140
120
H.P.
Crank End
100
-80
60
40
-20
-
L.P.
Head End
L.P.
Crank End
ENGINE No.Slc
140120100-
H.P.
Head End
80-
604020-
0-
-140
-120
H.P.
Crank End
-100
-80
-60
-40
-20
-
L.P.
L.P.
Head End
Crank End
ENGINE
No. 52.
Compound Condensing Engine.
H. P.
L.P.
Cylinder.
Cylixder.
Kind
Four valve
of engine
of cylinders
Diameter of cylinder
ins.
14A
Diameter of piston rod
ins.
SI
Number
2
2
ft.
Stroke of piston
%
Clearance
H. P. Constant for one lb. m.e.p., one
H.P.
rev. per minute
Ratio of areas of cylinders
Condition of valves and pistons regarding leakage
....
one 3i
one 4i
4
4
9
2i
.0367 each
Some
Data and Hesults of Feed -Water
TEhT.
Jackets on or off.
leakage
.2456 each
6.69 both
Some
leakaije
Tests.
A.
B.
C.
On.
On.
On.
I).
Off.
....
Character of steam
Ordinary Ordinary Ordinary Ordinary
Duration
hrs.
5.0
5.06
5.03
4.6
Weight of feed-water consumed lbs. 47,045.0 49,720.0 48,389.0 43,321.0
9,409.0
Feed-water consumed per hour
lbs.
9,812.5
9,614.4
9,626.9
lbs.
144.2
Pres. in steam pipe above atmos.
144.1
143.8
144.1
lbs.
8.6
12.2
Pres. in receiver above atmos.
4.9
12.3
ins.
25.2
25.0
Vacuum in condenser
25.3
24.9
76.86
78.80
Revolutions per minute
rev.
77.45
76.65
60.82
57.29
xVIean effective pressure, H.P. cyl. lbs.
61.12
60.53
11.0
9.76
10.6
9.66
Mean effective pressure, L.P. cyl. lbs.
342.48
323.48
Indicated horse-power, II. P. cyl. H.P.
347.63
350.79
415.29
Indicated horse-power, L.P. cyl. H.P.
371.22
398.84
374.41
Indicated H. P. whole engine
741.32
738.77
725.2
H.P.
718.85
Feed- water consumed per I. H. P.
13.23
13.01
per hour
lbs.
13.09
13.27
....
.
.
.
.
Measurements based on Sample Diagrams.
c.
Test.
Jackets on or off.
pressure above atmosphere
Corresponding steam-pipe and receiver
pressure above atmosphere
Cut-off pressure above zero
Release pressure above zero
Mean effective pressure
Back pressure at mid stroke above or
Initial
„.
On.
On.
Off.
H.P.
L.P.
H.P.
1
Off.
L. P.
.
.
lbs.
139.7
13.0
139.9
11.7
.
.
lbs.
12.3
22.4
5.6
11.07
144.6
140.0
44.0
60.3
12.8
21.4
lbs.
145.0
140.0
41.3
67.64
lbs.
+13.8
-12.2
+14.1
-12.2
....
....
below atmosphere
lbs.
lbs.
Proportion of stroke completed at cut-off
Steam accounted for at cut-off
lbs.
Steam accounted for at release
lbs.
Proportion of feed-water ace. for at cut-off
Proportion of feed-water accounted for
.
.
.
.
.
.
at release
206
.268
8.48
9.26
.651
.236
10.23
10.62
.786
.293
9.75
10.27
.734
.712
.816
.774
5.2
9.58
.213
8.71
9.79
.655
.73
;
ENGINE
No.
207
52.
Engine No. 52 is a pair of horizontal tandem compounds,
having jacketed cylinders and reheating receivers, the condensers being of the siphon type, to which water is supplied
The H.
by gravity.
P. cylinders are jacketed
over, but the
all
As
L. P. cylinders have only the barrels jacketed.
in the cas3
Engine No. 51, the reheaters are provided with sufficient
surface to superheat the steam passing to the low-pressure
The valves
cylinders, the water which remains being trapped.
of
are all of the gridiron type.
Steam
is
supplied by horizontal
return tubular boilers, and at the throttle valves
%
.1 of 1
The H.
of moisture.
it
contained
P. pistons leaked to
some ex-
and the head-end exhaust valve
tent,
of
the
left-hand low-
The
pressure cylinder leaked a considerable amount.
pistons
of the
H. P. cylinder and the remaining valves were
tight.
The load was cotton machinery.
trials were made with three different
Three
sures,
and a fourth
trial
with steam shut
fairly
receiver pres-
from the jackets
off
and the reheating tubes.
Comparing the results of these tests with those made on
Engine No. 51, which is of the same general type and of
about tlie same power, but having only half the number of
This engine did not
cylinders, there is a striking difference.
have the benefit of superheated steam as did Engine No. 51,
and this difference in the conditions must be taken into account
but
it is
hardly possible that the whole of the difference, which
about 9 %, could be produced in this way. There may be
some difference, also, in the amount of leakage of the two en-
is
gines.
Engine No. 51 had the benefit
Making
all
that the size of the cylinders
The
of the
allowances for these differences,
had some
effect
action of the steam in the cylinders
No. 52 from what
it is
in No. 51
;
but
is
best
it is
vacuum.
quite certain
upon the
results.
quite different in
it will
be noticed that
steam accounted for in the low-pressure cylinders
that
shown
in the
is greater than
high pressure cylinders, whereas in Engine
No. 51 the contrary
Comparing
jackets
off,
is
Test "
true.
C"
with jackets on, and Test "
the difference in the
economy shown
is
D"
with
only .26 of
ENGINE
208
TESTS.
The nature of the
shown in the analysis
a pound, or about 2 %.
action which the
jackets produced
of
With
is
the diagrams.
the jackets on, the steam accounted for in the low-pres-
sure cylinder
is
the greatest
;
whereas, with the jackets
steam accounted for in that cylinder
is
off,
the
the least.
Another noticeable thing in the action of the jackets is in
With
distribution of the power between the cylinders.
cylinders
developed 92 horsejackets on, the low-pressure
power more than the high-pressure cylinders, or about 30 %
whereas, with jackets off, the increase was only 24 horse-power,
the
;
or about 7 %.
—
The quantity of steam condensed in the jackets on the first three
was respectively, 11.4 %, 10.8 %, and 10.8 % of the total quantity consumed and these are included in the figures given in the tables.
Note.
trials
;
ENQINENo. 52q
140120100-
R.H.H.P.
Head End
8060-
40200-
-140
120
R.H.H.P. Crank End
100
80
60
-
40
20
-
15-
R.H.L.P.
10-
50510-
R.H.L.P.
Crank End
Head End
ENGINE No. 52c
140120-
L.H.H.P.
100-
Head End
8060-
40H
200-
-140
-120
100
L.H.H.P. Crank End
-80
60
-40
-20
-
L.H.L.P.
Head End
16-1
10-
5-
0510-
L.H.L.P.
Crank End
ENGINE No. 52d
140-1
120100-
R.H.H.P.
Head End
8060-
40200-
-140
120
R.H.H.P. Crank End
-100
-
80
-
60
-
40
-20
-
15-
10-
R.H.L.P.
5-
0510-
R.H. UP.
Crank End
Head End
ENGINE No. 52d
140—
120—
100-
806040-
200-
-140
-120
L.H.H.P. Crank End
-100
-
80
-60
-40
-
20
-
16
L.H.L.P.
Head End
10
6
O
6
10
15—1
10^
5
0510
ENGINE
No. 53.
Compound Condensing Engine.
H.P. Cylinder.
Four valve
Kind
of engine
of cylinders
Diameter of cylinder
ins.
Diameter of piston rod
ins.
Number
1
30
18
one
3i
4
3
Fairly tight
Data and Results of Feed -Water
Hi
4
3
.0608
....
Cylinder.
(Corliss)
1
ft.
Stroke of piston
Clearance
%
H. P. constant for one lb. m. e. p., one
rev. per min
H.P.
Ratio of areas of cylinders
Condition of valves and pistons regardins: leakage
.1685
2.77
Fairly tight
Tests.
Character of steam
Ordinary
Duration
3.0
consumed
Feed-water consumed per hour
Weight
L.P.
of feed- water
Pressure in steam pipe above atmosphere
hrs.
14,195.0
lbs.
4,731.7
lbs.
114.9
lbs.
Pressure in receiver above atmosphere
15.4
lbs.
Vacuum
25.6
ins.
65.5
rev.
in
condenser
Revolutions per minute
Mean
Mean
H. P. cylinder
35.07
lbs.
effective pressure, L. P. cylinder
14.27
lbs.
effective pressure,
Indicated horse-power, H. P. cylinder
142.1
Indicated horse-power, L, P. cylinder
157.6
Indicated horse-power, whole engine
Feed-water consumed per I. H. P. per hour
299.7
H.P.
H.P.
H.P.
15.78
lbs.
Measurements based on Sample Diagrams.
H. P.
Cylinder.
pressure above zero
lbs.
111.9
Cut-off pressure above zero
lbs.
Release pressure above zero
effective pressure
Back pressure at mid stroke, above or be-
lbs.
111.7
30.8
Initial
Mean
low atmosphere
lbs.
Proportion of stroke completed at cut-off
Steam accounted for at cut-off
r
Steam accounted for at release
Proportion of feed-water accounted for at
.
.
.
.
....
cut-off
36.65
lbs.
lbs.
lbs.
+
16.7
.238
11.31
9.47
L.P.
Cylinder.
14.6
33.2
8.7
14.52
-11.8
13.01
10.76
.717
.60
.825
.682
Proportion of feed- water accounted for at
release
2i;
ENGINE
214
Engine No. 53
is
TESTS.
a horizontal tandem compound, with un-
jacketed cylinders and jet condenser operated by an indepen-
dent air-pump.
an auxiliary
The steam from
The boilers
boiler.
the air-pump was taken from
are of the water-tube vertical
type, furnishing steam slightly superheated.
The steam passes
through a reservoir at the engine, which
drained by a trap
discharging to waste.
The valves and
ders were found to be in
fairly
is
pistons of both cylin-
good condition throughout.
The load on the engine was rubber-grinding machinery and
somewhat variable in its character.
The economy shown by this test, 15.78 lbs. per I. H. P. per
hour, is rather low compared with other compound engines of
this type.
The explanation of this result is found in part, at
least, in the small ratios of volumes of the two cylindere.
The
diagrams show the variable character of tlie load.
ENGINE No. 53
100
80
60
40
20
100-
806040200-
L.P.
L.P.
Crank End
Head End
ENGINE
No. 54.
Compound Non-Condensing Engine.
H. P. Cylinder. L. P. Cylinder.
Kind of engine
Single valve
Number
of cylinders
Diameter of cylinder
Diameter of pii-ton rod
Stroke of piston
1
ins.
ins.
%
Clearance
H.P. constant for one lb. m.e.p., one
revolution per minute
.H.P.
Ratio of areas of cylinders
Condition of valves and pistons regarding leakage
.
.
-
Tkst.
]yaler Test s.
.
.
.
.
lbs.
.
lbs.
Pressure in steam pipe above atmos.
Pressure in receiver above atmosphere
Revolutions per minute
Mean effective pressure, H. P. cylinder
.
effective pressm*e, L. P. cylinder
lbs.
lbs.
rev.
lbs.
lbs.
Indicated horse-power, H. P. cylinder H.P.
Indicated horse-power, L. P. cylinder H.P.
Indicated horse-power, whole engine
H.P.
Feed-water consumed i)er I. H. P. per
.
...
Measurements
lbs.
Jnised
on
>'«/ iple
6.0
17,918.0
3,583.6
1«6.9
28.2
275.7
29.06
7.94
58.5
44.88
103.37
Initial pressure above atmo.sphere
Corresponding steam-pipe and receiver
.
.
pressure
Cut-off pressure above zer
Release pressure above zero
>
.
....
.
.
.
effective pressure
Back pressure
at
'.
6.0
5.0
19,815.0
25,7.30.0
3,963.0
6,140.0
166.8
164.6
46.3
60.6
271.2
273.4
48.37
52.31
16.5
24.58
95.77
104.41
91.74
137.77
187.51
242.18
24.99
Diagrams, Test
H.P.
Cylinder.
Mean
(
v..
Ordinary Ordinary Ordinary
hrs.
Weight of feed-water consumed
Feed-water consumed per hour
hour
.0205
2.81
Some leakage
A.
Character of steam
Duration
Mean
2,
13
8
.0073
.
and Results of Feed
20
11
....
J)ata
1
12
2i
13
ins.
21.14
21.26
I 1.
L. P.
Cylinder.
lbs.
157.3
43.0
lbs.
46.0
39.9
lbs.
168.5
147.5
77.4
47.98
lbs.
41.6
.479
15.73
15.41
.499
14.71
14.51
.744
.696
.728
.080
lbs.
lbs.
2.3.9
16.36
mid stroke above
atmosphere
2.00
Proportion of stroke completed at cutoff
Steam accounted
Steam accountetl
for at cut-off
for at release
.
.
.
lbs.
.
.
.
lbs.
Proportion of feed-water accounted for
at cut-off
Proportion of feed- water accounted for
at release
216
ENGINE
Engine No. 54
cylinders.
is
a vertical cross
Each cylinder has
217
No. 54.
compound with unjacketed
a single
balanced slide valve,
and the speed is controlled by a shaft governor operating on
The steam is drawn from water-tube boilers
the H. P. valve.
through a considerable length of pipe, having headers and
separators which were thoroughly drained, and a calorimeter
attached near the engine showed that it was practically dry.
Steam condensed from the pipes was trapped and properly
allowed for.
The load consisted of two dynamos located on
The valves of both cylindere leaked a small
the engine shaft.
amount, and the piston of the H. P. cylinder leaked considerably
Three
at
full
tests
low-pressure
piston
was
tight.
were made with three different loads.
In these tests there
results of
The
pressure.
tests "
conditions of a
B"
is
medium
load,
be considered an overload.
pounding in engines
substantial
and " C "
;
agreement between the
and the
latter
This reveals the advantage of com-
of this class,
where by
benefits of expansion in the engine as a
out suffering the losses produced
early cut-offs.
made under
under what would
the former being
this
means the
whole are realized with-
in either cylinder
due to
ENGINE No. 54a
-120
80
40
L160-
I20H
80-
400-"
3020-
L.P.
Top
10-
0-
30-
L.P.
2010-
0-
Bottom
'
ENGINE No. 54b
r
H.P.Top
160
120
-80
40
160-
H.P.
120-
80-1
40-
0—
504030-
2010-
0-
504030-
2010-
0-
L.P.
Bottom
Bottom
ENGINE No. 54c
-160
H.P.Top
-120
80
40
U
160-
H.P.
120-
80-
40-
60-n
60
L.P.
Top
40
30-
2010-
60-|
50-
4030-
2010-
0-
UP. Bottom
Bottom
ENGINE
No. 55.
Compound Condensing Engine.
H.P.
Cylinder.
....
Kind
of engine
of cylincjers
Diameter of cylinder
Diameter of piston rod
Stroke of piston
Number
.
.
.
.
.
.
Four valve
ms.
ins.
.
....
1
28
56
6h
5
4.3
5
3.1
.7413
4.06
1827
.
.
....
Practically tight
Data and Results of Feed - Water
Character of steam
Duration
Weight of feed -water consumed
Feed-water consumed per hour
Pressure in steam pipe above atmosphere
Pressure in receiver above atmosphere (not verified)
Vacuum in condenser
Revolutions per minute
Mean effective pressure, H. P. cylinder
Test.
Ordinary
9 .5
...
.
Mean
effective pressure, L. P. cylinder
(Corliss)
1
5i
ft.
%
Clearance
H.P. Constant for one lb. m. e
H.P.
one rev. per min.
Ratio of areas of cylinders
Condition of valves and pistons
regarding leakage
.
L. P.
CVLINDER.
.'
.
Indicated horse-power, H. P. cylinder
Indicated horse-power, L. P. cylinder
Indicated horse-power, whole engine
Feed-water consumed per I. H. P. per hour
hrs.
216,002 .45
lbs.
22,737..1
lbs.
151,.5
lbs.
11 .8
lbs.
26 .8
nis.
75,.18
rev.
61,.76
lbs.
15 .53
lbs.
848..27
865..58
1,713..85
13..27
H.P.
H.P.
H.P.
lbs.
Measurements based on Sample Diagrams.
H.P.
Cylinder.
Initial pressure above atmosphere
Corresponding steam-pipe or receiver
.
.
pressure
Cut-off pressure above zero
Release pressure above zero
Mean
Back
....
....
effective pressure
pressure at mid stroke
lbs.
143
lbs.
151.0
152.3
44.4
61.53
lbs.
lbs.
lbs.
above or
below atmosphere
Proportion of stroke completed at cut-
lbs.
off
Steam accounted
Steam accounted
for at cut-off
for at release
.
.
.
lbs.
.
.
.
lbs.
L. P.
Cylinder.
15.5
+ 20.0
.326
10.84
10.84
*11.8
22.0
9.5
15.84
-11.5
.421
10.98
10.85
Proportion of feed-water accounted for
at cut-off
.817
.828
.817
.818
Proportion of feed-water accounted for
at release
Not
verified.
221
ENGINE
222
Engine No. 55
jacketed
cylinders
TESTS.
a cross compound with horizontal unand a reheating receiver. The steam is
is
exhausted into a surface condenser operated by an independent
steam-driven air and circulating pump.
The quantity
used by the condenser was determined
allowed
for.
The steam
is
both
cylinders were found
to be
The valves and
in
excellent
throughout, with practically no leakage.
electric generator located
on the main
for motors in a cotton mill.
steam
and
taken from vertical water-tube
boilers in a slightly superheated state.
of
of
independently
pistons
condition
The load was an
shaft, furnishing current
The steam condensed
in the re-
heater coil amounted to three and one half per cent of the total
weight of steam passing the throttle valve.
in the quantities given in the table.
This
is
included
A noticeable feature in these results is the close agreement
between the four quantities given for steam accounted for by
Three of these are practically equal, and the
the indicator.
fourth differs only one per cent.
ENGINE No.55
140120100-
H.P.
Head End
80-
60H
4020-1
0-
140
120
Crank End
H.P.
-100
-80
-
60
40
[-20
L.P.
Head End
I-
L.P.
Crank End
15
10
h
I-
5
5
10
ENGINE
No. 56.
Compound Condensing Engine.
H.P.
Cylinder.
Kind
Four valve
of engine
Number of
cylinders
Diameter of cylinder
ins.
22i
Diameter of piston rod
ins.
4.i
(Corliss)
1
1
ft.
Stroke of piston
Clearance
%
H. P. constant for 1 lb. m. e. p. one
H.P.
revolution per minute
Ratio of areas of cylinders
Condition of valves and pistons regarding leakage
.
.
.
42
4i
5i
3.5
4
3.5
.0799
.
....
.2897
3.63
1
Some
Some
leakage
leakage
Data and Results qf Feed - Water
Character of steam
Duration
Weight of feed-water consmned
Feed-water consumed per hour
Pressure in steam pipe above atmosphere
Pressure in receiver above atmosphere
Vacuum in condenser
Revolutions per minute
Mean effective pressure, H. P. cylinder
Mean
L. P.
CVLIX0EK.
Test.
Ordinary
5.0
hrs.
60. 636
12.
effective pressure, L. P. cylinder
Indicated horse-power, H. I*, cylinder
Indicated horse-power, L. P. cylinder
Indicated horse-power, whole engine
Peed-water consumed per I. II. P. per hour
lbs.
127.3
107.8
11.0
25.2
120.2
45.07
11.30
432.93
394.12
827.05
lbs.
lbs.
lbs.
ins.
rev.
lbs.
lbs.
H.P.
H.P.
H.P.
14.67
Measurements based on Sample Diagrams.
Initial pressiu-e above atmosphere
Corresponding steam-pipe and receiver
.
pressure
Cut-off pressure above zero
Release pressure above zero
Mean
.
....
....
effective pressure
Back pressure
at
102-2
11.1
lbs.
107.0
99.0
36.0
44.93
11.0
20.3
8.5
11.29
lbs.
lbs.
or
below atmosphere
lbs.
Proportion of stroke completed at cut-off
lbs.
Steam accounted for at cut-off
lbs.
Steam accounted for at release
Proportion of feed-water accounted for
at cut-off
of feed-water
for at release
Proportion
L. P.
Cylixdeb.
lbs.
lbs.
mid stroke abuv«
H. P.
CVLIXDEK.
.
.
.
.
.
.
+11.6
.331
11.87
12.91
-10.5
.362
10.46
11.79
.813
.716
.8S
.806
accounted
224
i
ENGINE
Engine No. bQ is a tandem compound
eted cylinders and reheating receiver.
the bottom of each cylinder, and the
thoroughfare through which it passes to
The
top.
waste.
A
jackets
jet
are
Steam
it
is
taken
contained 0.8
valve.
tion,
•^^
of
best.
is
supplied to
jacket spaces form a
the steam chest at the
is
is
to
used, with an independent steam-
supplied from an independent boiler.
from horizontal return
The valves and
but not the
with horizontal jack-
Steam
drained by traps which discharge
condenser
driven air-pump, which
225
No. 56.
tubular boilers, and
moisture at a point near the throttle
pistons were found to be in fair condi-
The
load consisted of an electric gene-
rator placed on the driving-shaft, which for the test supplied
current to a water rheostat.
This
is
an example of a Corliss engine running at compara-
tively high rotative speed
and piston speed
as well,
erally considered to be one of the conditions
which
is
gen-
which contribute
good economy. The result, however, is nothing unusual.
The conclusion cannot fairly be drawn from this test that such
to
a speed produces no advantage
;
for there were other conditions
pertaining to the work, such as the pressure and vacuum, wliicli
were unfavorable to economy.
ENGINE No.56
I00-|
80—
H.P.
Head End
60-
4020-
0-
100
H.P.
Crank End
-
80
-
60
-40
-20
-
L.P.
L.P.
Head End
Crank End
ENGINE
No. 57.
Compound Condensing Engine.
H. P.
L. p.
Cylixdkk.
Cylinder.
Kiud
Four valve
Number
1
1
28
56
6
5
of engine
of cylinders
Diameter of cylinder
Diameter of piston rod
Stroke of piston
ins.
ins.
ft.
%
Clearance
5
2.6
Horse-power constant for one lb. m.e.p.
one revolution per minute
H.P.
.
.
.1844
.
....
Ratio of areas of cylinders
Condition of valves and pistons regarding leakage
3.7
.7425
.03
PrEwctically tight
Data and Results of Feed - Water
Test.
Ordinary
Character of steam
Duration
Weight of feed-water con.sumed
Eeed-water consumed per hour
Pressure in steam pipe above atmosphere
Pressure in receiver above atmosphere
Vacuum in condenser
Revolutions per minute
Mean effective pressure, H. P. cylinder
Mean
(Corliss)
5.0
94,545,
18,900.
hrs.
lbs.
lbs.
133.00
13.60
25.20
66.04
52.27
effective pressure, L. P. cylinder
Indicated horse-power, H. P. cylinder
Indicated horse-power, L. P. cylinder
Indicated horse-power, whole engine
Feed-water consumed per I. H. P. per hour
lbs.
lbs..
ins.
rev.
lbs.
14.37
lbs.
636.61
704.64
1341.25
14.10
H.P.
H.P.
H.P.
lbs.
Measurements Based on Sample Diagrams.
H.P.
Cylinder.
Initial pressui-e above atmosphere
Corresponding steam-pipe and receiver
.
pressure
Cut-off pressure above zero
.
....
....
Release pressure above zero
effective pressure
Back pressure at mid stroke above or
Mean
below atmosphere
Steam ac^counted
for at release
lbs.
125.2
13 9
lbs.
133.0
121.3
38.9
51.87
20.8
10.1
14.5
lbs.
lbs.
lbs.
lbs.
Proportion of stroke completed at cut-off
Steam accounted for at cut-off
L. P.
Cylinder.
+16.3
.294
.
.
.
lbs.
.
.
.
lbs.
9 82
10.34
13.1
-11.4
.429
11.22
11.57
Proportion of feed-water accounted for
at cut-off
Proi)ortion of feed-water accounted for
at release
227
.696
.796
.733
.821
ENGINE
228
TESTS.
Engine No. 57 is a cross compound with unjackfeted horizoncylindei-s and a reheating receiver.
The condenser is of
the siphon type, the water for which is supplied by an independent steam pump which takes steam from the main pipe
tal
and exhausts into the
receiver.
Steam
is
furnished by vertical
water-tube boilers in a slightly superheated
The leakage
load was cotton machinery.
valves and pistons were
all in
tests
The
showed that the
condition.
excellent condition throughout,
excepting the exhaust valve at the crank end of the low-pressure cylinder, which leaked a considerable amount.
A
test
pump
that
.9 of
was made
of the
steam consumed by the condenser
when exhausting into the condenser; and
it
a
it
was found
used, under these circumstances, 1,176 lbs. per hour, or
pound per
the receiver, as
it
I.
H. P. per hour.
did on the
test,
When
exhausting into
the consumption was consid-
was
by
power developed in the low-pressure cylinder.
It is estimated that .5 of a pound per I. H. P. per hour is
chargeable to the condenser pump when used as it was on the
main test. The effect of exhausting the pump into the receiver
in this way is indicated in the analysis of the diagrams, which
shows a considerably larger amount of steam accounted for
in the low-pressure cylinder than that shown in the H. P.
erably greater
increasing the
cylinder.
;
but a large proportion of
it
utilized
ENGINE No. 57
I20-,
100
H.P.
80
Head End
60H
40
20-
0-
-120
100
H.P.
Crank End
80
.60
40
20
L.P.
L.P.
Head End
Crank End
ENGINE
No. 58,
Compound Condensing Engine.
Kind
ins.
.
.
.
1
26
50
5
5.0
ft.
4
4
4
4.8
.1269
.
....
tiirht
liesults
Character of steam
Duration
hrs.
Weight of feed-water consumed
lbs.
Feed-water consumed per hour
lbs.
Pressure in steam pipe above atmos.
lbs.
Pressure in receiver above atmo.sphere lbs.
ins.
Vacuum in condenser
Kevolutions per minute
Mean effective pressure, H. P. cylinder lbs.
.
.
.
A.
B.
Constant.
Vakiable.
Ordinary
Ordinary
.
2.5
34,040.0
13,616.0
.
13().2
34,239.0
11,413.0
128.9
16.8
26.2
78.0
12.8
26.2
78.0
.
effective pressure. L. P. cylinder
4(J8.97
560.19
Measureu tents based on Sample JHagrams. Test
i
pressure
Cut-off pressure above zero
Release pressure above zero
.
....
....
effective pressure
Back pressure
at
mid
L. P.
CVI.IXDEK.
lbs.
136.0
120.7
37.9
47.85
lbs.
4.
H. P.
131.9
lbs.
.
Cylindek.
lbs.
lbs.
843.44
13.53
1,030.06
13.21
.
Initial pressure above atmosphere
Corresponding steam-pipe and receiver
3.0
47.38
15.24
lbs.
Indicated horse-power, H. P. cylimler H.P.
Indicated horse-power, L. P. cylinder H.P.
H.P.
Indicated horse-power, whole engine
Feed-water consumed per I. H. P. per hr. lbs.
.
tiirlit
of Feed -Water Testf
Test Load.
Mean
.4719
3.72
Practically
1
Prai'tlcallv
leakaire
Data and
(Corliss)
1
ins.
%
Clearance
H, P. constant for one lb. m. e. p., one
per
minute
H.P.
revolution
Ratio of areas of cylinders
Condition of valves and pistons regard-
Mean
L. p.
Cylixdeb.
Four valve
of engine
of cylinders
Diameter of cylinder
Diameter of piston rod
Stroke of piston
Number
iiiir
H. P.
Cylixdek.
18.2
16.7
125.2
8.5
15.17
stroke, above or
below atmosphere
lbs.
Proportion of stroke completed at cut-off
Steam accounted for at cut-off
Steam accounted for at release
Proportion of feed-water accounted for
.
.
.
lbs.
.
.
.
lbs.
at cut-off
+ 21.2
.293
10.56
10.92
-12.8
.274
9.48
9.69
.8
.718
.826
.733
Proportion of feed-water accounted for
at release
230
ENGINE
Engine No.
58
jacketecl cylinders
of the jet type
is
No.
231
58.
compound with horizontal unreceiver.
The condenser is
a cross
and a reheating
with an independent steam driven air-pump, the
quantity of steam used by which was determined and allowed
The steam is taken from water-tube boilers, and at the
was found to contain .2 of one per cent of moisture.
The load was an electric generator carried by the flywheel shaft, and on Test " A " the current was consumed in a
water rheostat, while that of Test " B " was used by the motors
of an electric street railroad, and the load was variable.
The
for.
throttle valve
valves
and pistons were
an
in
unusually tight
condition
throughout.
The weight of steam condensed in the reheater coil on
"A" was 500 lbs. per hour, or about .5 of a pound per
test
I.
H. P. per hour; and
in the tables.
this is
included in the quantities given
In the diagrams Avhich are appended for the
variable load test, the
two extreme
lines are
reproduced which
were taken for a period covering ten consecutive revolutions.
During the whole trial with variable load, the maximum variation
was shoAvn by the extreme readings of the
The highest was 1,456 amperes and the lowest 624.
of the load
ammeter.
The next highest readings were 1,300 amperes, and
the next
lowest 669.
* These figures were determined, from ten sets of diagrams, the average
developed by the whole engine being 1029.16. The average
horse-power used for working up the results (1030,6) was determined from the
average electrical readings, using the efficiency corresponding to the readings
horse-power
when
the ten sets were obtained.
On
the variable load test the horse-power
was determined from the electrical readings by using the average efficiency
found by independent tests made with a steady load, this load being the average
load of the main trial.
KNQIN^No. 58a
120100-
H.P.
80-
Head End
60-
40i
200-"
-120
H.P.
Crank End
HOC
80
1—60
40
-20
—
20
16
L.P.
Head End
10
S
6
10
20
16
L.P.
Crank End
10
5
6
10
ENGINE No.58b
120100-
H.P.
80-
Head End
60-
40H
20-
0-i
-120
-100
H.P.
Crank End
— 80
— 60
—40
20
L-
p20
— 15
L.P.
Head End
-10
—
5
—
—
6
-10
- 20
- IS
L.P.
Crank End
-
10
-
6
-
10
6
1
TEIPLE EXPAlSrSIOI^ ENGHSTES.
235
ENGINE
No. 59.
Expansion Engine.
Triple
Int.
H. P.
L. P.
Cylinder. Cylindeb, Cylinder.
Four valve
Kind
of engine
of cylinders
Diameter of cylinders
Number
Diameter
ins.
of piston rod
1
1
20
34
ins.
Stroke of piston
Clearance
H. P. Constant for one lb. m.e.p., one
rev. per minute
Ratio of areas of cylinders
Condition of valves and pistons regardiuir leakage
....
ft.
%
1 1.
2
36
41
6
41
41
5
2.5
5
2.5
1
Cons id.
leakage
Data and Results of Feed -Water
Character of steam
Duration
Weight of feed-water consumed
Feed-water consumed per hour
Pressure in steam pipe above atmosphere
Pressure in first receiver above atmosphere
Pressure in second receiver above atmosphere
Vacuum in condensers
Revolutions per minute
Mean effective pressure, H. P. cylinder
Mean effective pressure, intermediate cylinder
5
2.5
.2727 .3017 each
2.94
6.5 twc
Practic'ly Practic'ly
.0928
P.
(Corliss)
tight
Test.
Superheated 39°
10.375
461
670.9
12,670.
effective pressure, L. P. cylinder
.
.
.
,
.
.
hrs.
lbs.
lbs.
151
.
lbs.
33
,
lbs.
4
27
65.24
59.59
13.19
10.19
360.9
234.7
401.2
996.8
12.71
....
Mean
tight
.
horse-power, H. P. cylinder
horse-power, intermediate cylinder
horse-power, L. P. cyliniler
horse-power, whole engine
Feed-water consumed per I. H. P. per hour
Indicated
Indicated
Indicated
Indicated
lbs.
ms.
lbs.
lbs.
lbs.
H.P.
H.P.
H.P.
H.P.
lbs.
Measurements Based on Sample Diagrams.
H.P.
L. P.
Int.
Cylinder. Cylinder. Cylinder.
Initial pressure above atmosphere
Corresp. steam-pipe pressiu-e
Cut-off pressure above zero
Release pressure above zero
Mean effective pressure
Back pressure at mid stroke above or
lbs.
below atmosphere
Proportion of stroke completed at cut-off
Steam accounted for at cut-off
Steam accounted for at release
Proportion of feed-water accounted for
lbs.
.
.
.
.
.
....
....
142.
152.
32.9
lbs.
lbs.
145.2
lbs.
53.
lbs.
60.56
38.7
17.4
13.22
.
.
.
lbs.
.
.
.
lbs.
at cut-off
+32.6
+4.8
4.1
16
6.7
10.16
-12.5
.346
9.81
10.42
.406
9.53
10.45
8.39
9.95
.773
.741
.60
.82
.822
.783
.357
Proportion of feed-water accounted for
at release
237
ENGINE
238
Engine No. 59
in the
manner
is
a horizontal four-cylinder engine, arranged
of a pair of
cylinders nearest the
which there
of
TESTS.
are two.
tandem compound engines.
The
high-pressure cylinder
low-pressure cylinders, and
one of the
The
beds are the low-pressure cylinders, of
cylinder in front of the other.
The
is
in front
intermediate
the
cylinders are jacketed on
the system which allows the steam which is supplied to the
cylinder to
being
The
pass through the jacket space, each jacket thus
first
filled
with steam having the
pressure of supply.
initial
jackets are drained into i-eceivers, and these are provided
They discharge
with pumps operated by the engme.
water into reheaters placed in the
steam which
is
flue of the
formed in the reheaters
is
the
The
boilers.
supplied to the
re-
ceiver between the intermediate and the low-pressure cylinders.
This receiver
is
provided with a
coil of live
of
steam pipe pre-
The
senting 33 square feet of exterior surface.
total quantity
water condensed in the jackets and withdrawal from them
amounted
tity of
to 691 lbs. per liour, or about 5 9^ of the total quan-
steam supplied to the engine.
was re-evaporated
pressure cylinders.
are of the jet type,
in
About
the reheater and
The condensers,
of
utilized in
the low-
which there are two,
and operated by direct connected air-pumps.
supplied from vertical tubular boilers, and on the test
Steam
was superheated 39° at a point near the
is
one-lialf of this
it
boilers.
With
the
exception of the iugh-pressure piston, whicli leaked quite badly,
the valves and pistons were all in a practically tight condition.
The load on
the engine consisted of cotton machinery.
The
loss of steam which, referring to the analysis of the diagrams,
took place between the intermediate cylinder and the low-presnoticeable in view of the arrangements
made
sure cylinders
is
to reheat the
steam in the receiver, and augment the supply
by means of the jacket-water re-evaporated in the flue heaters.
It shows the powerful action of cylinder condensation, and the
necessity of employing more efficient means for overcoming
the loss.
V
ENGINE No. 59
-140
120
H.P.
Head End
100
80
-
-60
-40
-20
-
140
120-
H.P. Crank
End
100-
80
60
40
20-1
Int'"
Head End
40
30H
20
10
Int'"
Crank End
40
30
20
iO
-
LNGINENo. 59
R.H.L.P.
Head End
6
6
10
L-15
R.H.L.P.
Crank End
605-
10-
15-
L.H.L.P.
Head End
5-
OH
6-
1015-
L.H.L.P.
Crank End
5
5
10
1-15
ENGINE
No. 60.
Triple Expansion Engine.
H. P.
Cyl.
L. P.
Int. Cyl,
Cyl.
Kind
Four valve
Number
1
1
1
ins.
28
48
ins.
two 4
two 4
74
two 4
ft.
5
of engine
of cylinders
Diameter of cylinder
Diameter of piston rod
Stroke of piston
.
.
Clearance
Ratio of areas of cylinders
Condition of valves and pistons regarding
leakage
%
1.4
1
Mean
Mean
effective pressure, intermediate cylinder
effective pressure, L. P. cylinder
Indicated horse-power, H. P. cylinder
Indicated horse-power, intermediate cylinder
Indicated hor.se-power, L. P. cylinder
Indicated hor.se-power, whole engine
Feed -water consumed per I. H. P. per hour
5
1.5
2.98
7.11
Fairly
Fairly
Fairly
tight
tight
tight
Data and Eesults of Feed-Water
Character of steam
Duration
Weight of feed-water consumed
Feed-water consumed per hour
Pressure in steam pipe above atmosphere
Pressure in first receiver above atmosphere
Pressure in second receiver above atmosphere
Vacuum in condenser
Revolutions per minute
Mean effective pressure, H. P. cylinder
(Corliss)
Test.
Ordinary
....
....
....
72.0
18,811.0
7,205.7
125.6
30.3
hrs.
.8
lbs.
lbs.
lbs.
lbs.
lbs.
25.3
20.99
49.85
rev.
15.4
7.57
191.3
lbs.
nis.
lbs.
lbs.
176.04
206.39
573.73
12.55
H.P.
H.P.
H.P.
H.P.
lbs.
Measurements based on Sample Diagrams.
Initial pressure
Corresponding
above atmosphere
steam-pipe and receiver
.
.
.
pressure
H.P.
Int.
Cyl.
Cyl.
lbs.
124.3
30.4
lbs.
129.7
134.1
44.7
50.07
30.1
30.3
14.3
15.41
Cut-off pressure above zero
Release pressure above zero
lbs.
Mean
lbs.
lbs.
effective pressure
Hack pressure
at
mid
0.2
1.0
11.5
5.8
7.59
stroke, above or be-
low atmosphere
lbs.
Proportion of stroke completed at cut-off
Steam accounted for at cut-off
Steam accounted for at relea.se
Proportion of feed-water accounted for at
.
....
....
cut-off
lbs.
lbs.
+29.4
-11.9
.338
9.48
9.96
0.0
.362
9.63
9.97
.756
.759
.753
.793
.794
.789
.479
9.45
9.91
Proportion of feed-water accounted for at
relea.se
241
ENGINE
242
Engine No. 60
is
TESTS.
a vertical triple expansion
with jacketed cylinders and two reheaters.
pnm ping-engine
Only
tli«
barrels
of the cylinders are jacketed, the heads being unjacketed, ex-
cept so far as the valve chests, which are located in the heads,
furnish a substitute.
is
The
jacket of the low-pressure cylinder
supplied with steam at a reduced pressure.
The remaining
The
jackets and the reheaters are supplied with boiler steam.
engine
is
furnished with steam from horizontal return tubular
and at a point near the throttle valve the percentage of
There was no undue leakage
moisture was found to be .3 %.
of the valves and pistons, but they were not in a perfectly tight
boilers,
condition.
The load
each cylinder
of
is
that of a direct-acting
pump, the diameter of each plunger Ijeing 36,
head, expressed in pounds, 53.4
lbs.
"
and the
per square inch.
total
The
consumed 955 lbs. of steam per hour, which is 12.7 % of
and this is included in the quantities
total used by the engine
When the engine was at rest, the jackets
given in the tables.
consumed 163.5 lbs. per hour, being the loss due to radiation.
The analysis of the diagrams in this test shows a remarkably
close agreement between the steam accounted for by the indi-
jackets
;
cator in the various cylinder.
1
%
is
a variation of less than
between the quantities shown at the cut-off in the three
and a similarly close agreement in the three quanti-
cylinders,
ties
There
shown
at
tlie
release.
ENGINE No. 60
120-
100-
H.P.Top
8060-
40 H
20-
0-J
120
H.P Bottom
-100
1—80
-60
-40
-20
I—
p30
-20
-10
-
-30
-20
-10
-
O
ENGINE No. 60
L.P.
Top
On
L.P.
Bottom
12
-
1
SUMMABY OF FEED -WATER
t- cc cc cc r-
o --
cN c»
o CO
i>- !^^
^
(
245
TESTS.
'-0
o '^ CO <©
'o Ci
-ti Tti
•>i =^_
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t^
c: t^
•to r-i
o cc "M o
o o CO i- CD
1— lo c; OJ
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u-? !>.
i-o i>-
5tC^^SoCOOOCOTt«OCO(NCCCOCOOrHOXOt-OCO
Cut-off.
Indicated
GC c: GO
POWER.
t^ CO
^' "^
a a
O (N O
O O QC oi t^ o"
O O* CO
OO
O
0'!^i75oJ=!55(?3lQOT=icOCOCOOOCO>-HOOO'MrH^COGqrH
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z
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o
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o
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tight
44
>>
44
44
44
44
44
44
44
44
44
44
44
44
44
44
44
44
44
44
Fairly
^1
i-
44
tight
tight
44
leakage
leakage
44
Fairly
44
44
leakage
44
44
44
44
44
44
Considerable
Fairly
Some
Some
Fairly
Some
(C
£
E
3
](JO
82°
(»f
37° 37° 24° 24°
25°
41°
59°
CO
Ordinary
Steam.
Ordinary
44
44
Ordinary
44
44
44
Ordinary
44
Quality
E
Superh'd
44
44
Superh'd
Superh'd
Ordinary
Superh'd
5
§^
^saaaoa
SS
fl^
a
k4
44
44
44
44
44
44
44
44
44
4.
44
44
valve
valve
44
Four-valve(c)
>4
44
44
44
44
44
44
44
44
44
44
44
44
44
44
44
44
44
44
44
44
44
44
44
4.
44
44
Four-valve
Four-valve(c)
Four-valve(c)
44
•nanrcnii
valve
44
Four-valve
Double
44
44
Single
Single
<<MCOCO'^tOCOt^XXOiC100'—<'MC0-+iiCCOCOCOt^
i—I"—''—
,—
1
P-l
,— ^1
_
r-l
,—
ENGINE
246
TESTS.
H.P.
PER
Water
PER Hour.
Feed-
I.
AT
FeedProportion
Water
ACCOUNTED
Cut-off.
FOR
OF
i
»O00'-iCCOii3<IQO'MCC'Ma0i-"C0t^C0C5r-i-^CS,-(CC'>t^Q0'-i
0000i-HO«-Hi3<ICCt^O^r^»-H'<!*<C0C^i-H^.CSCC-^5<IQ0'MI-CC
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t
o
a
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1
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rt
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5^
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li
"8
^
a
o
2
o
^
2
o
:
:
::
::
r
r
::
::
-
::
^
X
'
o
of
Steam.
Quality
^
OC
9-S^
9c
.
OR
Condensing
non-
Condensing.
5z;o
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15 «.!
SUMMABY OF FEED -WATER
247
TESTS.
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ENGINE
248
TESTS.
H.P.
Water
PER
PER
Hoi'R.
Feed-
^' -t >c -t TC
iri c<i »-^
oj CO CO CO
o
TjJ 1-1 T-i
oi -^
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AT
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1-1
FeedProportion
Water
ACCOITNTED
«t^t-
Cut-off.
P.
FOR
OF
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670.5
658.
650.1
1008.6
718
741.3
738.8
725.2
200.7
103.4
187.5
242.0
676.2
1713.8
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® -^ 00
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3
144.1
ur oi
1
CO
3
si
<
tight
tight
>k
tight
tight
leakage
44
44
44
44
leakage
leakage
a
44
44
14
44
44
44
44
44
44
44
44
44
44
44
44
44
44
SB
^5
U
44
Fairly
Fairly
Some
44
44
Practically
Some
44
Practically
S
Some
a.
o
8
2°
12° 13° 20°
iW
16.7°
16.4°
12
44
Ordinary
Ordinary
Superh'd
Superh'd
"
"
"
be
c
2
a
o
s
1
Jr.
§
r
OB
Condensing
NonCondensing.
valve
44
44
44
44
44
44
44
44
44
44
44
(4
44
(4
>
44
44
44
44
44
44
44
44
44
(4
44
Four-valve
Four-valve
Four-valve(c)
Four-valve(c)
Four-valve(c)
44
44
44
44
•aaaiviix:
Single
r
r
gg
KEVIEW OF FEED-WATEK
240
TESTS.
REVIEW OF FEED -WATER
TESTS.
It could hardly be expected that conclusive information
upon
the subjects which are of most interest in connection with the
operation of steam engines could be obtained from a large
ber of tests
made on engines
different conditions of service,
num-
running under
and located in plants which are
of various sizes,
not always best adapted for experimental purposes or research,
like the tests
under consideration.
Such
tests,
however, cannot
but bring out some points on these subjects which are of considerable practical value,
if
for
were,'in the main, conducted
practical operation
The
tion,
no other reason than that the
tests
under those very circumstances of
which alone could give results
of that nature.
tests furnish information in regard to cylinder condensa-
leakage of valves and pistons, the effect of pressure and
speed, the
economy
of
condensing and superheating, the relative
economy
of simple,
effect of
steam jacketting and reheating, the effect of different
compound, and
ratios of cylinder areas in
laneous questions
I.
;
triple
compound
expansion engines, the
engines, and some miscel-
and these are discussed
in the order
named.
CYLINDER CONDENSATION AND LEAKAGE.
Cylinder condensation and leakage
water consumption which
is
is
that part of the feed-
not accounted for by the indicator
It is necessary to put these two losses in one class.
no way of separating them either absolutely or approximately.
The only practicable thing to do is to test the
valves and pistons for leakage with the engine at rest and if
under these conditions they prove to be tight, it is fair to as-
diagram.
There
is
;
sume
that the leakage under conditions of running
is
practically
nothing, and the
part not accounted for by the diagram is
wholly or substantially cylinder condensation.
If a similar
engine, working under similar conditions,
251
is
found by such
tests
ENGINE
252
to leak,
and then a comparison
and that
tight engine
drawn as
amounts
TESTS.
made between
is
in the leaking engine,
to the extent of the leakage
cj^illy, it
may
amount
of cylinder condensation, for
is
found
in
it is
unnecessary to
know is what the
amount to when the engine
ing condition.
These
is
made on simple
made from
the
list of
the absolute
;
and, after
the im-
all,
cylinder condensation and
in ordinarily
tests furnish satisfactory
point, esjjecially those
properly be
know
loss
Practi-
seldom that an engine
it is
an absolutely tight condition
portant thing to
leakage
and how much the
whole consumption.
to in percentage of the
be said that
the loss in the
an inference can be
good work-
evidence on this
engines.
Selection
may
simple engines, those of the
larger sizes of the four- valve type, using ordinary steam, taking
amount
those which are tight or leaking only a small
those
and
numbered
31.
1,
2,
;
namely,
3, 5, 6, 7, IT, 18, 20, 22, 25, 28, 29, 30,
These are tabulated as follows, being arranged
order of the point of cut-off
:
—
I'KoloKTION
<»i-
No. OF
Engine.
31
A
31
18
C
B
31 I)
20
A
3A
30
3B
22
31
C
18
A
29
20
31
B
F
7
26
6
17
28
A
5
2
31
B
1
A
1
17
B
B
ClTT-OFF.
.041
.084
.111
.121
.119
.1.38
.139
.100
.172
.178
.188
.194
.222
.231
.237
.243
.252
.264
.271
.303
.315
.323
.367
.375
.385
Fkki>-
Watek
A<(<»IXTKD
FOR AT
Cut-off.
.382
.509
.668
.588
.615
.654
.645
.695
.(M)9
.709
.725
679
.722
.745
.750
.737
.757
.770
.781
.784
.817
.796
.840
.839
.820
Cylinder
C<>NDENSATIOX AND
Leakage.
.618
.491
.332
.412
.385
.346
.355
..305
.331
.291
.275
.321
.278
.255
.250
.263
.243
.230
.219
.216
.183
.204
.160
.161
.180
in the
EEVIEW OF FEED-WATER
These proportions
better be
of cylinder
examined by referring
which they
253
TESTS.
condensation and leakage can
to the
accompanying chart on
are plotted, ordinates or verticals representing per-
centages of cut-off, and abscissae or horizontals, percentages of
The curved line drawn through
them represents the mean curve of condensation and leakage
deduced from these results. It clearly shows that the percen1>
condensation and leakage.
age rapidly increases as the point of
and
at the
bears
cut-off
very large proportion to the
a
becomes
earlier,
very earliest cut-off the condensation and leakage
total
consumption
of
steam.
The
best series
of
tests
on this subject, using the same
made on Engine No.
engine, are those
31,
which was a pair
of
Corliss non-condensing engines having cylinders 16 in. diameter
and 42
in. stroke.
This engine was
^practically tight,
and the
j)ercentages of condensation (and leakage) over a range of cut^
from 4% to 32% was from 62% down to 20%.
That leakage has an important effect upon the economy of
an engine is well shown by a comparison of the results obtained
from engines which leaked excessively with those shown on
the chart.
For example, in Engine No. 19, which is of the
single-valve type showing considerable leakage compared with
off
Corliss engines, the proportion of steam accounted for
30%
at
cut-off,
giving condensation and
leakage of
is
.706
29.4%.
The condensation and leakage shown on the average curve of
is about 20%, so that the difference
between 20 and 29.4 must be due in a laige degree to leakage.
In Engine No. 26 a test with a leaking exhaust valve showed
the chart at that cut-off
When
condensation and leakage of 30.8%.
repaired and
down
to
made
tight, the
the valve had been
condensation and leakage dropped
25.5%, the difference being due almost entirely to a
reduction in leakage.
The saving
in actual feed-water con-
sumj^tion was about 10%.
In the
compound engine
tests
which can be compared for the
purpose of studying cylinder condensation, the range of cutoff
in the high-pressure
cylinder
is
as a basis for satisfactory conclusions.
hardly sufficient to serve
The
tests
which can be
70
^
60
\
\
chart
1
1
\
-J
50
•o
c
a
|of
1
CONDENSATION AND LEAKAGE
1
1
for
\
Tight or Fairly Tight Simple inglnes
using
Ordinary Saturated Stea m
\o
1
\
c
.m40
a
N
.
o'^
(li
c
0)
o
T3
a
fv
N?
o V
§30
^V^
N»?
^*v
k L^
n
20
o
^o7
10
10
15
20
25
Percentage of Cut
30
off
35
40
45
REVIEW OF FEED-WATEU
fairly
compared
for this purpose are those
TESTS.
numbered
255
32, 34, 36,
The range of cut-off in the high49, 53, 55, 56, and 58A.
pressure cylinder is from .238 to .331, and the range of steam
accounted for at cut-off in the same cylinder is from .717 to
These are tabulated below:
.866.
No. OF
Engine.
Proportion of
Feed- Water
Accounted for
AT Cut-off,
Cut-off,
H. P. Cyl.
H. P. Cyl.
32
36
49
53
55
56
58
A
Average,
The average
.305
.295
.330
.238
.326
.331
.293
.774
.767
.866
.717
.817
.813
.800
.303
.793
cylinder condensation
and leakage in these
=
20.7%, and the average cut-off in the highIf these be compared with the
pressure cylinder is .303.
leakage
given on the chart for the
and
condensation
of
curve
cases
is
100-79.3
simple engines,
it will
be seen that this average falls closely
upon that curve. The point on the curve for 30% cut-off is
20.5%. The engines selected are those in which the high-pressure cylinder is unjacketed, or of the class in which the jacket
space forms a thoroughfare through which steam is supplied
It may be inferred from the close agreement beto the chest.
tween the average of these tests and the indications of simple
engines in the matter, that the curve of condensation and leakage for simple engines applies also to the high-pressure cylinder
of
compound engines where
these are unjacketed, and where
the valves and pistons are fairly tight.
Condensation and leakage in the low-pressure cylinder of the
compound engines reported above
is
affected to a considerable
extent by the conditions regarding jacketing
Where
there
is
and reheating.
neither jacketing nor reheating, the conden-
:
ENGINE
256
sation and leakage
is
much
TESTS.
greater in the low-pressure cylinder
For example, reference may be made
to Engines No. 32, 36, 46A, 47A, 48B, 52D, and 53, in which
the proportions of cylinder condensation and leakage are as
than in the H. P. cylinder.
follows
No. OF
Engine.
COXDEXSATION
Condensation
AND Leakage
AND Leakage
32
36
46
47
48
62
63
A
A
B
D
Average,
The average
of
these
Cut-off
Cut-off,
H. P. Cyl.
L. P. Cyl.
.226
.233
.194
.212
.144
.266
.283
.28
.36
.29
.32
.26
.35
.40
.222
.323
shows
10% more
condensation and
leakage in the L. P. cylinder than in the H. P. cylinder.
That leakage in itself produces an important effect in compound engines is exhibited in the case of one engine reported,
that of No. 38, where the feed-water consumption lier I. H. P.
The leakage here was in the low-presper hour is 19.36 lbs.
sure piston and although the cylinders of the engine were jacketed, and the receiver also jacketed, the condensation and
leakage at cut-off in the H. P. cylinder was 32.5% against
17.5% by the simple-engine curve, and 57.0% at cut-off in the
L. P. cylinder; the increase between the two cylinders being
;
24.5%.
If
we may judge from
indications of one test, that of Engine
No. 26, the effect of leakage upon the consumption of steam
and economy of the engine may be exceedingly marked, and at
the same time have so little influence upon the lines of the
diagram that it may be scarcely noticeable. In this instance,
the form and position of the expansion line with reference to a
hyperbolic curve drawn through the cut-off point of the diagram
is so nearly the same that careful measurements would hardly
REVIEW OF FEED -WATER
a difference, although
distinguish
valve leaked no less than
10%.
TESTS.
257
exhaust
one case the
in
Practically the
same
effect, or
rather want of effect, has been noticed in one other case where
a broken packing-ring in
amounted
which
caused a leakage
a piston
A
to a still larger quantity.
close examination of
the expansion line of the diagrams, before and after, failed to
reveal any clearly defined difference.
This
is
Engine No.
In a case like that of the compound Engine No. 38,
78.
cannot
it
be inferred from this that the influence of excessive leakage
could not be revealed by a study of the indicator diagrams.
Here
it
did produce a marked effect in the distribution of the
load between the cylinders, cutting
in the L. P. cylinder,
tent in
down
and increasing
the H. P. cylinder.
At
it
power developed
the
to a
corresponding ex-
the same time,
it
caused a
noticeable " drop " in pressure at the high-pressure release.
In studying the effect of cylinder condensation and leakage,
and the extent
shown
the loss which
of
it
produces, the quantity
diagram
at the cut-off point of the
is
selected in prefer-
ence to that shown at the release, in the belief that at the cutoff
cal,
extent of
point the full
If the
indicated.
the loss
is
is
selected.
larger at the release than
is
more truthfully
is
the same at one point as at the other, and
not matter which point
for
loss is the
tlie
steam accounted for at both points
to re-evaporation during
it is
If the
identiit
does
quantity accounted
at the cut-off,
which owing
expansion frequently occurs, the appar-
ent loss due to condensation and leakage
is
less at the release
Sometimes there
is
as
than
it is
cent less
at the cut-off.
much
as 10 per
apparent condensation and leakage at the
than at the
cut-off.
release
In cases like this the release percentage
does not show the full extent of
ered on account of re-evaporation
loss,
is
because the work recov-
in no sense proportional to
the increase in the steam accounted for at that point.
Neither
does the loss at cut-off in such cases represent the true
and the reason
the same
loss,
but the loss at cut-off furnishes a
closer indication of the true loss than the loss at release, and
is
;
a better basis for the study of the question of cylinder condensation.
ENGINE
258
TESTS.
It will be noticed in the table giving the quantities upon
which the chart of cylinder condensation and leakage is based,
that no distinction is made between engines which are condensIt is probable that the
ing and those running non-condensing.
transfer of heat from the steam to the metal of the cylinder,
under the action of the comparatively low temperature of the
is different from that which occurs in the non-con-
condenser,
and if a suitable investigation were made, this
would appear in the percentage of cylinder condenWhatever this difference may be, it is not sufficiently
densing engine
;
difference
sation.
.
marked to be noticeable in the tests referred to in the chart;
and consequently the results are used indiscriminately, whether
the engines are condensing or non-condensing.
II.
EFFECT OF PRESSURE ON THE ECONOMY.
Other things being the same,
it is
a well recognized princi-
ple in steam-engineering that the higher the pressure the
economical the
consumption
and consequently,
its use are not always tlie same
examining the results obtained from different engines, such
attending
in
more
But circumstances
steam.
of
;
as those here reported, it does not follow that in
ual case where the pressure
the greatest.
is
highest the economy
For example, two
any individ-
is
necessarily
tests are reported
on Engine
No. 18, which show practically the same economy as measured
by the feed-water consumed per I. H. P. per hour yet the
;
pressure in one case
is
is
84
lbs.,
and
59 lbs. It
which accompanied
in the other case
evident that the difference in the cut-off
of pressure exerted such an influence that the
might have been derived from a higher pressure
which
benefit
was counterbalanced.
There are two instances among the simple engines which
may be examined to show the importance due to increased
Test No. 1 A and test No. 2 is one of these inpressure.
Here an increase of the pressure from 72.3 lbs. to
stances.
101 lbs., accompanied by a slight shortening of the cut-off, had
a marked effect in improving the economy, the consumption of
the
change
REVIEW OF FEED -WATER
feed-water being reduced from 27.8
259
Another
to 25.8 lbs.
lbs.
comparison may be made between
TESTS.
No. 7 and test No.
test
Here, with the same cut-off, an increase of pressure
31 F.
from 80.5
lbs. to
98.6
lbs.
was evidently the principal cause of
lbs. per I. H. P. per
a reduction in the consumption from 29.03
hour
to 25.31 lbs.
In the list of the compound engines, there are two tests
which can be compared for this purpose,
those numbered 32
and 36. In No. 32, with a pressure of 94.8 lbs., and the cutoff in the high pressure cylinder .305, the feed-water consumpIn test No. 36, with
tion is 16.28 lbs. per I. H. P. per hour.
126.8 lbs. pressure, and the cut-off at .295, or practically the
same as in the other case, the consumption is reduced to
—
14.05
lbs.
That an increased pressure
same engine is advantashown by test 48 A
the pressure was 100.2 lbs., and the
in the
geous under some circumstances,
is
clearly
and 48 C. In the latter
consumption of feed-water 15.08 lbs., while in the former the
pressure was 125,9 lbs., and with practically the same load, the
consumption was 14.12 lbs. In this case the benefit due to
the increase of pressure was largely enhanced by the increased
expansion obtained, the cut-off in the H. P. cylinder dropping
from .432 to .294.
EFFECT OF SPEED UPON ECONOMY.
in.
The
speeds, expressed in revolutions
these tests from a
With such
tion
as
minimum
a wide range, there
to
the
economy
to
of
is
21 to a
maximum
of 356.7.
reason for expecting informa-
be derived from increasing the
rotative speed, but the tests furnish
this subject.
per minute, vary in
no conclusive evidence on
The high-speed engines
are
all,
or nearly
all,
of a
from the low-speed ones, and the nature of the
design and construction is such that certain features which are
different class
necessary for the highest economy are sacrificed in order to
obtain the desired increase of speed.
Many
of the high-speed
engines have a single valve which performs
all
the four valves
The
in a
slow-speed engine.
the functions of
result
is
that
ENGINE
260
TESTS.
these functions are not so perfectly performed, in the engines
which run at high speed, and there
is
a loss of economy.
Furthermore, the valves in the high-speed engines are generally
of
and valves of this kind are not so well
tight construction, and do not maintain so tight a
some balanced type
adapted to
;
condition as those of the four valves in slow-speed engines.
Again, the high-speed engines usually require larger clearance
For
spaces in the cylinders than those of the slow-speed class.
these various reasons, the high-speed engine
is
handicapped at
the outset with conditions which are unfavorable to
and
if
the
effect
of the
high speed
is
economy
advantageous,
advantage must be so great as to overcome the losses noted
is
to
show
in favor of the high-speed engine
An
jected to a test.
examination of the
when
is
it
tests reported,
;
the
if it
sub-
taking
those engines which are run at the highest speeds, shows that
in
every case they are less economical than the slow-speed
engines, and in every case the reason appears in one or
There
the points mentioned.
paratively low
economy
the fact that in almost
more of
a furtiier reason for the com-
of the high-speed engines repoi-ted, in
all
cases the engines given are of com-
and this, no doubt, has an important
making the engine less economical than it would
paratively small size
influence in
is
;
otherwise be.
There
is
one case given where a Corliss engine was run at a
speed of one hundred and twenty revolutions per minute,
of
Engine No. 66
;
and
this
may
be compared with the other
Corliss engines running a lower speed.
ever,
is
— that
not a very satisfactory one
;
The comparison, howbecause the valves and
pistons were not in the best condition in regard to leakage, and
the boiler pressure was rather lower than that obtained on other
engines with which
it
Looking
could be compared.
at
the
proportion of steam accounted for by the indicator, which
is
.813, there is nothing in this indication to
show any marked
improvement due
if
to the
high rotative speed,
such existed.
BE VIEW OF FEED-WATER
rV.
TESTS.
ECONOMY OF CONDENSING.
the popular mind, that the
It is held, in
261
economy
of con-
round numbers, 25%. This percentage usually
densing
relates to simple engines, and it refers to the economy as measured by the difference in the coal consumption produced by
in
is,
The evidence
a condenser.
shows that
this
special cases.
belief
some
of
of the
tests here
not well founded, unless
is
The economy due
it
given
be in
condensing ought to be
to
reckoned on the basis of coal consumption, and not alone on
the basis of feed-wat^ consumption
because a non-condensing
;
engine is usually accompanied by a feed- water heater, and some
of the loss of economy produced by running non-condensing is
made up by
the saving of coal due to
If the feed-water is heated
warming the
feed-water.
by the exhaust steam of the non-con-
densing engine from a temperature of 100°, which
is
that of the
ordinary hot well, to a temperature of 210°, the non-condensing
engine can be credited with about 119© less coal consumption.
This matter should properly be taken into account when con-
economy produced by a condenser.
of simple engines, a number of comparisons are
made on the same engine when carrying the same load, one
test being made with the engine condensing and the other
non-condensing.
In the case of Engine No. 10, where such a
comparison was made, the feed-water consumed when running
non-condensing was 25.64 lbs. per I. H. P. per hour, and when
sidering the
In the
list
running condensing, 20.51
lbs.,
the difference being 5.18
lbs.,
Engine No. 17, which
or 20%
was tried in the same manner, the consumption running noncondensing was 28.93 lbs., and condensing, 22.08 lbs., the
of
difference
In
the larger quantity.
being 6.85, or
24%
of
the
Engine No. 20, a similar test was made
in one case
was 30.16
ference being 7.16
lbs.,
and
lbs.,
or
24%
larger
;
quantity.
In
and the consumption
in the other 28 lbs., the difof the larger quantity.
The
average of these three comparisons gives a saving produced
by condensing of 22.3%. If we allow for the steam or power
used by an economical condenser, it will be seen that the net
ENGINE
262
economy
and
much
is,
at
of
steam consumption.
we allow
more,
not
condensing
on the basis
of
this is
TESTS.
best,
difference
for the
over
If,
20%
;
further-
produced by heating the
feed-water to the extent mentioned above, the saving of fuel
would be reduced to about 11%. In some cases in practice
where these conditions exist, the difference in favor of condensing might be greater, owing to the evaporative economy
of the boilers being improved by reducing the work upon
them but all that could be fairly expected on the basis of
these three engines, other things being the same, would be not
;
much
over 10%.
and that
is another method of looking at this subject
compare the best ijerformance of engines running condensing with the best results running non-condensing.
The
There
;
to
is,
best non-condensing result, in the
oixiinary steam, is that of
100
simple engines using
list of
Engine No. 31 F, working at about
pressure at .231 cut-off, and developing 287.1 indi-
lbs.
cated horse-power.
This result
is
25.39
lbs.
The
best result
obtained from a condensing engine, using ordinary steam,
that of No.
cut-off, the
lbs.
is
per
I.
22,
working at a pressure
is
of 82.3 lbs. at .172
I. H. P.
This is 18.49
Comparing these two figures, there
engine developing 613.4
H. P. per hour.
a difference in favor of the condensing engine of 6.9
lbs.,
Allowing for steam or
or 27.2% of the
power used by the condensing apparatus, the net economy
larger
in feed-water
consumption
quantity.
is
not, at best, over
25%
;
and
fur-
ther allowance for the gain due to heating the feed-water, as
estimated in the former case, would bring
to about
17%.
tlie
coal-saving
It appears, therefore, that the tests here
down
given
on simple engines do not confirm the popular impression that
the saving produced by condensing is 25%.
The economy
of
condensing, as compared with
non-con-
densing, depends to some extent on the type of air-pump and
condenser
these
:
—
employed.
There
are
four
principal
classes
of
The jet condenser and direct-connected air-pump, which
supplied by the main engine.
power
uses
1.
REVIEW OF FEED- WATER
2.
The siphon type
of condenser, in
plied by gravity, and no air-pump
3.
The siphon condenser,
in
is
263
TESTS.
which the water
is
sup-
required.
which the water
is
supplied by
an independent pump.
4.
The
jet condenser,
with air-pump driven by an indepen-
dent engine or other motor.
In
all of these,
diture of
mth
the exception of the second, the expen-
power or the consumption
can be arranged to
must be charged
Those that use steam
of steam
against the saving due to condensing.
a portion of
utilize
that steam in cases
where the exhaust from the independent engine or
carried through a feed-Avater heater,
the boiler.
pump
and the heat returned
is
to
In test No. 15, which was provided with a jet
condenser and direct-connected air-pump, the amount of power
used by the air-pump was found to be 1.8% of the working
In Engine No. 57, which was propower of the engine.
vided with a siphon condenser supplied with water by an
independent pump, the quantity of steam used by the pump,
when exhausting into the condenser, was 6.7% of the total
consumption of steam by the- engine. In Engine No. 19,
which was provided with a jet condenser operated by an in-
dependent steam-driven air-pump, the consumption of steam
by the pump when exhausting into the air was 13% of the
In Engine No. 20, which
used by the engine.
was fitted with a similar condenser, the quantity of steam
used by the air-pump when exhausting into the condenser
was over 13% of the total quantity. When an independent
steam-driven air-pump is used, and the heat of the exhaust
steam is returned to the boilers so far as possible by heating
the feed-water, it is probable that from one-half to two-thirds
of the steam is saved
and in a case where the air-pump uses
12% of the entire quantity, tlie actual loss of coal due
to the
air-pump woukl be not over 4 or 5%. From these
considerations it appears that in cases where an air-pump
total quantity
;
pump
or other condenser
is
required,
the
charged to the condenser on this account
stances, about
2%
;
and
in
cases where
percentage to be
is,
in
the best in-
the exhaust steam
ENGINE
264
from the motor
not
is
TESTS.
properly utilized,
as to largely offset the
it
may
be so great
economy otherwise resulting from the
use of the condenser.
The
some data
tests furnish
compound
as to the
economy produced by
In Engine No. 33, with
practically the same load, the use of the condenser reduced
a condenser in
the consumption
lbs.
to 18.92
of
lbs.,
engines.
steam per
or
16%.
I.
H. P. per hour from 22.53
In Engine No. 45, the use of
the condenser, with a nearly constant load, reduced the con-
A
sumption from 23.24 lbs. to 16.07 lbs., or 31%.
son may be made between Engines 41 and 42.
(42 B), running non-condensing, used 25.2
per hour
19.1
lbs.
;
Engine No. 46, which
is
latter
H. P.
run non-condensing, may be com-
for
is
run condensing, making
the difference in the condition of
In this instance the condenser appeai-s to have
feed-water consumption about 30%.
is
I.
and the former (41 B), running condensing, used
The reduction due to condensing here is 24%.
pared with Engine No. 48, which
allowance
per
lbs.
compari-
The
In
the steam.
i
educed the
these no account
all
taken of the steam used by the condensing apparatus, the
percentages given being the gross savings.
gine No. 33, which
may
possibly not useful for general comparison,
effect of the
Throwing out En-
be regaided as of special design, and
it
appears that the
condenser on the compound engines
greater than in the case of the simple engines.
is
considerably
It will be seen,
however, that the advantage of the condenser in compound
engines depends largely upon the boiler pressure
;
and a com-
made on an engine like No. 41, which is running at 130
lbs., would show very differently from what it would in an enThe
gine like No. 54, for example, which is run at 167 lbs.
effect of the vacuum on the low-pressui-e cylinder is nnich more
telling when the boiler pressure is low, and less work is done
in the high-pressure cylinder, than it is when the boiler pressure
parison
is
high.
At
pressures ranging between 120 and 140
lbs.,
it
would
appear from these records that a 4-valve compound engine running non-condensing would use not over 21.5 lbs. of feed- water
REVIEW OF FEED-WATER
per
H. P. per hour
I.
;
TESTS.
265
and a similar engine running condensing,
with the usual proportions of cylinders, would use not over
14
The
lbs.
35%
difference
between the two
in favor of the condensing engine.
is 7.5 lbs.,
or about
Allowing, say,
2%
power used by a direct-connected air-pump, and making
further allowance, as in the case of the simple engines menfor
tioned, for the effect of a feed-water heater, the net saving of
fuel in favor of the condensing engine is about
The
ning one end of one cylinder non-condensing
tion of feed-water
Engine No.
shown
in
two
from 21.11
9
to utilize a
is
lbs. to
22.68
lbs.,
or about
7%.
consumption amounted to
The object of running an engine in this man-
about 12%.
ner
is
In Engine No. 3 the effect was to increase the consump-
cases.
In
25%.
on a pair of condensing engines produced by run-
effect
the
increased
portion of the steam for heating the feed-
water, or for other uses to which exhaust steam can be adapted.
use
If its
is
confined to heating feed- water, and the
amount
is
110°, or that corresponding to the instances heretofore noted,
an advantage would be produced, provided the increased consumpti(m did not exceed 11%,. If in these two engines the
exhaust steam from the single end were used for that pur-
would be a net gain corresponding to about 7%
Engine No. 3, and a net loss coiTesponding to 1% in
Engine No. 9.
pose, there
in
V.
The
effect
engine
No. 1
is
EFFECT OF SUPERHEATING.
which superheating has upon the economy of an
clearly
shown
C was made
in the case of
Engine No.
1,
where
test
with the steam superheated 82°, and test
B
under practically the same conditions, except that the
steam was practically dry. This was a simple non-condensNo. 1
ing engine.
The economy produced by
sufficient
reduce the feed-water consumption from
to
H. P. per hour, to 26.83
the superheating
was
29.34
8.6% or about
This may be examined fur1%
ther by comparing this and other simple engines which use
superheated steam with those using ordinary steam. The effect
lbs.,
per
I.
for each 10° of superheating.
lbs.,
or
:
ENGINE
266
TESTS.
can best be studied by comparing the cylinder condensation and
leakage, in the case of the engines using superheated steam,
with the curve of condensation and leakage given on the chart
for simple engines using ordinary steam.
case of test No. 1
C
the cut-off
is
For example,
in the
.392, the proportion of feed-
water accounted for at cut-off .947, and the cylinder conden-
On
sation and leakage 5.3%.
the
curve for ordinary steam
referred to, the condensation and leakage at a cut-off of .392
is
16.7%.
The
difference
11.4%, represents the
between 5.3 and
16.7,
which
is
reduction in the condensation due to
the superheating, as determined by this method of comparison.
Pursuing
engines,
matter in
the
we have
the
same way for
ProporOF
Superheating.
1
c
4
8
A
8B
9
A
9B
16
^
Average,
From
82
26
37
37
24
24
69
Propor-
Feei>-
tion OF
.947
.766
.819
.747
.820
.836
.896
.392
.233
.247
.166
.186
.226
.281
comparison
Cylinder
Condensation and
Water
Cut-off.
.053
.234
.181
.25:3
.180
.164
.106
41°
this
remaining
Proportion ReCylinder Leakage
DERIVED
duced BY
CondensaAccounted tion and
FROM
Superfor heating.
fob at
Leakage. Curve
ordinary
Cut-off.
Steam.
tion OF
Degrees
No.
the
the following table
.167
.266
.243
.334
.307
.261
.216
.114
.021
.062
.081
.127
.097
.110
.087
it
appears that with steam superheated
41° (generally at a point near the
boilei-s,
and a considerable
distance from the engine), the proportion of condensation and
was reduced an average of 8.7%. Assuming as a
between the actual saving in the case of
No. 1 Engine, and the reduced proportion of cylinder condensation, which was about .8, this reduction in the cylinder con-
leakage
criterion the relation
densation corresponds to an actual saving of feed-water of 7%.
Assuming that if the engines had been supplied with ordinary
REVIEW OF FEED- WATER
TESTS.
steam, this steam would have contained
1%
responding in round numbers
20° of
to,
say,
267
of moisture, cor-
superheating^
the steam in the two cases,
about 60°. According to this
difference in the quality of
the
expressed as superheating,
is
calculation, therefore, the effect of the superheating
duce the feed- water consumption
over
60°, or a trifle
1%
7%
for a
for each 10°
and
;
is
to re-
superheating of
this
practically
corroborates the evidence furnished by the tests on Engine
No.
1.
The compound engine which shows
any in the list,
and although
tlie
is
one which
this fact
is
may
the highest
economy
of
supplied with superheated steam
;
be considered as one reason for
high result, there were other conditions which were favor-
able,
and the exact
effect of the superheating
is
a matter of
conjecture.
Incidentally,
a
marked
should be noted that superheating produces
it
effect in the character
indicator diagram.
of the
In Engine No. 1 this
expansion line of the
is
clearly revealed
by
a comparison of the steam accounted for by the indicator at
cut-off
and
release.
In test No. 1 B, where the engine was
running with ordinary steam, the proportion accounted for at
cut-off is .839,
and that
at release is .861,
which
is
an increase
On the other hand, on test No. 1 C, where the steam
was superheated 82°, the proportion accounted for at cut-off
was .947, and at release .900, there being a reduction here
of .047.
This change is evidently due to the reduced condensation produced by the superheating, and the consequent
reduction in the amount of re-evaporation during expansion.
of .022.
VI.
RELATIVE ECONOMY OF SIMPLE, COMPOUND AND TRIPLE
EXPANSION ENGINES.
In comparing the Economy of a compound or other multiple
expansion engine with that of a simple engine, the question
be raised.
What
One method
may
should be the conditions of the comparison
?
comparing the two would be to select those running under the same boiler pressure and quality of steam, and
of
ENGINE
268
TESTS.
with similar provisions in regard to jacketing.
This method
be interesting and valuable for scientific research
may
practically
little
showing the advantages
of
compound
but for
;
engines,
it is
of
importance, because one of the principal objects in com-
pounding
is
to enable the
economy due
and
to large expansions
high pressures to be obtained without the sacrifice which such
expansions produce when carried on during the single stage
in one cylinder.
which occurs
The nearest approach
parison of this kind, derived from the tests reported,
provision was
is
com-
that of
which was made with a boiler presHere the engine was unjacketed, and no
compound Engine No.
sure of 94.8 lbs.
to a
made
32,
for re-heating
between the cylinders.
If
we compare this with the very best result obtained from a
simple condensing engine, that of No. 22, there appears, even
under these circumstances, a marked difference in favor of the
These figures are 18.49 for the simple
compound engine.
compound; and the difference is 2.21
Comparing this, again, with simple Engine
engine, and 16.28 for the
or about
lbs.,
12%.
No. 28, which
is
running at 70
of 19.45 lbs. of feed-water per
is
3.17
lbs.,
lbs.
I.
pressure on a consumption
H. P. per hour, the difference
or 16.3%.
A fairly satisfactory comparison between compound engines
and simple engines, where no jacketing or re-heating is proThis
vided, can be made by using compound Engine No. 36.
but the jackets were not drained, and
engine was jacketed
;
consequently, inider the circumstances, they were ineffective.
In this engine the consumption of feed-water was 14.05
lbs.
H. P. per hour when running at a pressure of 106.8
lbs.
per
we comjmre
If
is
I.
this Avith
No. 28, simple engine, the difference
5.4 lbs., or 27.8%.
A
general comparison between the
engines
may
be
made without regard
compound and simple
to the matter of pressure
or the use of jackets and re-heaters, and Avithout regard to the
quality of the steam, omitting the three engines which have an
excessively high ratio of cylindier areas.
The engines
are those of the Corliss or other 4-valve type.
son
is
made
in the following tables.
selected
Such a compari-
BE VIEW OF FEED-WATER
TESTS.
269
Simple Condensing Engines.
Feed-Water Consumed
Nl'MBER.
PER
I.
A
A
8B
9 A
18 A
21.11
19.39
18.71
18.25
20.31
20.56
18.49
19.45
21.42
3
8
B
18
H. P. PER Hour.
22
28
30
Average,
19.74
Compound Condensing Engines.
Feed-Water Consumed
Number.
PER
I.
32
34
36
16.28
13 28
14.05
13.37
13.26
14.12
14.01
15.08
14.18
13.28
15.78
13.27
14.60
14.10
13.21
37
43
48
48
48
A
B
C
49
60
53
66
66
57
58
A
Average,
The average
is
19.74
14.12
lbs.,
lbs.
the
The
case
14.12
on the simple condensing engines
on the compound condensing engines,
of the results
and
of those
difference
water consumption
In
H. P. per Hour.
of
4-valve type, there
is
5.62
lbs.,
or
28.5%
of the feed-
of the simple engines.
non-condensing compound engines of the
only one engine in this class, Engine No.
is
ENGINE
270
Test No. 46
46.
B
on
this
TESTS.
engine gave a feed- water consump-
may
be compared with Engine No. 2,
which was run non-condensing at a pressure of 101 lbs., and
gave 25.8 lbs. consumption. Here the economy due to the
compound engine is 4.21 lbs., or 16.3%. This is rather unfavorable to the compound engine on account of the relatively
tion of 21.59 lbs.
This
small difference in the boiler pressures.
Referring to the single-valve engines running condensing,
may be made between Engine No. 41 and Engine
Engine No. 19, the simple engine, used 27.15 lbs. per
I. H. P. per hour, and Engine No. 41 B, compound, used 19.1
lbs., the difference being 8.05 lbs., or an economy of 29.6%.
comparison
No. 19.
There are no single-valve engines of the non-condensing class
which to make a fair comparison between the com-
from
pound and simple engines, owing
sizes
;
to the great difference in the
but the results obtained on engines of this kind, disre-
garding their
size,
are
of
the
same kind
as
those
already
discussed.
The results of the tests on the two triple expansion engines
which are given, show an average consumption of 12.63 lbs.
This is below the average of
of water per I. H. P. per hour.
14.12 lbs. for the various compound condensing enghies which
are tabulated, and it is below the result obtained from any
individual engine given in that table.
It is l)etter to the ex-
10%, compared with the average. This result is not,
however, so good as that obtained from the special compound Engine No. 51, where the i-atio of cylinder areas is
tent of
about the same as the ratio between the low-pressure cylinder
and the high-pressure cylinder of triple expansion engines.
VII.
ECONOMY OF STEAM JACKETING AND RE-HEATING IN
COMPOUND ENGINES.
There are two compound engines given where the
effect of
shutting off the steam from the jackets and re-heater tubes
was
tested, these being No.
47 and No. 52.
In each of these
cases, the difference in the feed-water consumption per
I.
H. P.
REVIEW OF FEED-WATER
TESTS.
271
Both of these are cases where the ratio
two cylinders was unusually large, and the
re-heating surface in the receiver was also unusually large,
being sufficient to superheat the steam that passed into the
low-pressure cylinder. Whatever value jacketing and re-heating
per hour was 2%.
of
area
of
compound engine, it may be reasonably expected
would show to the best advantage where the expansion
may have
that
is
it
the
in a
carried to the greatest extent
tions of these
two cases are
and consequently the condi^
good showing for
;
-
as favorable to a
the jackets as they could be in most engines of the
type.
It
would appear
then, that
2%
is
compound
the most that can be
expected for the saving of steam due to jackets and re-heaters
in ordinary
compound engines
of the types referred to.
There are none of the tests of the other compound engines
which furnish much actual data on the subject but it may be
;
said that the superficial indications of the results of the tests
where the engines are jacketed, furnish
little ground for the
had much effect upon the economy. Take
the case of Engine No 58 A, which had no jackets, but which
was fitted with a re-heating receiver. The consumption of
feed- water was 13.21 lbs. per I. H. P. per hour, and this is
lower than any result given where the engine was provided
with jackets. No doubt the unusually tight condition of the
valves and pistons in this case had a favorable effect but if
jacketing is necessary for good economical results and the
advantage it produces is a marked one, its absence in Engine
No. 58 should have produced a much more noticeable effect.
Beyond the saving in steam consumption produced by jackets, which in Engines No. 47 and 53 amounted to 2%, there
is a further saving in fuel which cannot be overlooked, which
may be obtained by returning the hot water condensed in the
belief that jacketing
;
jackets
to
ordinarily
the
The temperature
boilers.
about 300°, and
was 7.7% in one
9.8% for the two.
of feed- water
is
case,
its
and
If the
of
this
quantity on the
11%
in
the
water
tests
other,
is
noted
averaging
temperature of the main supply
100°, the return of this water to the boilers
would add about 19°
to the
temperature
of
the feed-water,
ENGINE
272
and increase the
2%.
efficiency of
the
a
boilers
little
less
than
temperature of the main feed- water was at a
the
If
TESTS.
higher point, the effect of the heat returned from the jackets
would be correspondingly
we should have
age case, 1^%,
we make
If
less.
the
this for an avercombined economy of the
jackets due to both causes about 3^9^.
There
is
one test of a compound engine which was made to
determine the
of
(Effect
shutting off the steam from the re-
where the cylinders were unjacketed. This reEngine No. 48. Test A was made with the re-heater
heater, in a case
lates to
on,
and
test
B
with the re-heater
off.
The
figures
show
that
most economical in the latter case, the
difference between .11 of a pound or .7 of 1%
so that in
this one instance it would seem that the use of the reheater produced a loss in steam consumption instead of a
the engine was
the
;
gain.
If
allowance
turned from the
advantage from
there
of
was
made
is
for the heat
which could be
water of condensation to the
the
woukl be nearly 1%, so that
advantage in fuel economy due to the use
this
a slight
boilers,
re-
source
the re-heater.
Whatever
the actual
economy due
to
jacketing or to re-
heating or to both, which from the evidence of these tests
appears to be rather small, there
is
no question but that the
action of the jacket and the re-heater produces a powerful influence on the steam in
effect
upon the
its
The
The use
passage througli the cylinders.
indicator diagrams
is
very marked.
makes the engine more powerful in view of
work done by the low-pressure
cylinder for a given amount performed by the high-pressure
In Engine No. 47, the low-pressure cylinder decylinder.
of these appliances
the fact that
it
increases the
veloped 34 horse-power less than the high-pressure cylinder
when
the jackets and re-heater were off, and 10 horse-jx)wer
more than the H. P. cylinder when the jackets were on. In
Engine No. 52, the low-pressure cylinder developed 24 horsepower more than the H. P. cylinder when the jackets and reheater were off, and 92 horse- power more when the jackets
In Engine No. 48, the low-pressure cylinder dewere on.
REVIEW OF FEED-WATER
veloped 56 horse-power
re-heater Avas
off,
TESTS.
273
than the H. P. cylinder
less
and 19 horse-power
less
when
when
the
the re-heater
was on.
The effect of the jacketing and re-heating is also seen to
be very marked when comparison is made between the steam
accounted for in the two cylinders. In Engine No. 47, with
the jackets
at cut-off
off,
is
the steam accounted for in the L. P. cylinder
10.8%
less
than in the H. P. cylinder; whereas
with the jackets on, the difference
No. 52, with jackets
cylinder
is
8.4%
off,
the jackets were on,
the steam
than
less
it
is
In Engine
only 1%.
accounted for in the L. P.
When
the H. P. cylinder.
in
was 12.9% more than
the H. P.
in
Engine No. 48, the steam accounted for in
the L. P. cylinder with the re-heater off, was 11.6% less
than that in the H. P. cylinder; whereas, when the re-heater
was on, it was only 4.2% less. In Engine No. 55 the effect
In
cylinder.
of the re-heater on the diagrams is seen to be considerable,
from the fact that the steam accounted for in the L. P.
cylinder is 1.3% more than that accounted for in the H. P.
cylinder.
VIII.
EFFECT OF RATIO OF CYLINDER AREAS IN
COMPOUND ENGINES.
In most of the compound engines given, where these are of
the Corliss or other 4-valve type, the ratio of cylinder areas
between 3.5 and
the ratio
is
4.
about 7
The engines with
the large ratio of cylinder area
The
economical results than the others.
noticeable in No. 52 as
cases,
tests
it is
however, the pressure
in Nos.
is
;
and
nishes one reason for the better result.
show more
difference
47 and 51.
higher than
given with the lower ratios
pressure of 151
is
Three cases are given, however, where
to 1, these being Engines 47, 51, and 52.
it is
is
not so
In both these
in
most
of the
this higher pressure fur-
There
is
one case of a
an engine having a low ratio with which
these may be compared, and that is Engine No. 55.
This
engine gives a horse-power for 13.27 lbs. of feed- water per
lbs. in
ENGINE
274
hour.
Engine No. 47
51 C, gives 11.89
which
is
B
is
gives 12.45
lbs.,
while Engine Xo.
Taking the average
lbs.
12.17, there
TESTS.
of the last two,
a difference between the two cases in
favor of the larger ratio of areas of 1.1
lbs.
or
8%.
Engine
No. 55, as will be seen, does not give so well-formed diagrams,
there being considerable wiredrawing in the H. P. cylinder;
and the result obtained on this engine is not so good as it
would have been if these conditions had been better. Making
due allowance for this, however, and further allowance for the
fact that Engine No. 51 was supplied with slightly superheated
steam, there appears to be a noticeable advantage in the use of
the higher ratio of cylinder area for an engine running at 150
lbs. pressure.
It is a
of area, an excellent
noteworthy fact that with the high ratio
steam distribution, and a slight amount of
superheating, the most economical result given in the whole
of tests is produced,
power
— Engine
C producing
list
a horse-
for 11.89 lbs. of feed- water per hour.
IX.
The
No. 51
tests furnish
MISCELLANEOUS.
some indication
produced by light loads, especially
In Engine No. 16, which
is
as to the loss of
in
economy
non-condensing engines.
a single-valve, single-acting engine
consumption of steam per horsepower per hour was increased from 32.6 lbs. to 36.27 lbs., by
reducing the horse-power developed from 44.8 H. P. to 25.7
In Engine No. 23, which is of the single-valve highH. P.
sj)eed class, the consumption increased from 30.63 lbs. to 31.78
lbs., corresponding to a reduction of load from 39.4 II. P. to
22.2 H. P.
In Engine No. 31, which is of the Corliss type, the
consumption was fairly constant with a load varying from 222
H. P. to 342 H. P., but with lighter loads it rapidly feU off;
and with the load of the idle engine and shaftuig, which was 37
horse-power, the consumption rose to 73.63 lbs. per I. H. P. per
hour.
In Engine No. 42, which is a single-valve high-speed
compound, the consumption was increased from 25.2 lbs. to
44.89 lbs. by reducing the load from 152.5 H. P. to 45.6 H. P.
of the high-speed class, the
REVIEW OF FEED-WATER
TESTS.
275
In Engine No. 54, which is a single-valve compound, the feedwater consumption was nearly constant for loads of 242.9 H. P.
and 187.5 H. P. but it was increased from 21.14 lbs. to 24.99
In Engine No. 41, a
lbs. bj dropping the load to 103.4 H. P.
single-valve compound condensing, the consumption was increased from 19.1 lbs. to 22.74 lbs. by reducing the load from
;
196.8 H.P. to 90.5 H.P.
In Engine No. 45, which
compound condensing,
valve
from 15.71
17.22
lbs. to
lbs.
H. P. to 123.4 H. P.
Very little information
is
a double-
consumption was increased
by reducing the load from 244.5
the
of definite character
is
furnished by
the tests as to the effect of size of cylinder on economy.
Most
of the smaller engines given are of the single-valve class,
with
shaft governors, running at high speed; and although these
show
generally
hardly be
when
it
larger engines,
Two
to
show
would
it
to the smaller size of cylinder
other differences of condition are
importance.
seem
economy than the
less
fair to attribute
known
much
to be of
cases are given for Corliss engines which
that a consideral)le difference of size has
no
appreciable
These are Engine No. 2, having a 28.5"
59.5''
non-condensing cylinder, and Engine No. 31, which
X
had 2-16" x 42" cyUnders. The former gave a horse-power for
25.8 lbs. of feed-water per hour and the latter, when working
effect.
;
at about the
same
the same result.
cut-off, for 25.9 lbs.
per hour, or practically
Cylinder condensation and leakage
greater in the case of the smaller engine
;
and
is
2.1%
this fact fur-
nishes a slight indication that the smaller engine was the more
wasteful.
It
needs but a glance at the results of the various tests to
show that
the 4-valve engines are more economical as a type
than those having a less number of valves; and this
is
true
whether they are simple or compound, and whether condensing
or non-condensing.
The
single-valve
compound non-conden-
Engine No. 54, compared with the 4-valve compound
non-condensing Engine No. 46, shows a better result, some
sing
2%
;
but
it will
pressure of 165
be observed that the former works under a
lbs.,
while the pressure in the latter case
is
135.
ENGINE
276
As
the
economy
TESTS.
non-condensing compound engines
of
is
greatly
affected by the boiler pressure, the single-valve engine in this
case has an undoubted advantage, which more than
for the difference produced
omy
of the 4-valve type
is
by the
The
valve.
makes up
superior econ-
evidently due in part to the better
distribution of the steam in the cylinders, as revealed
some cases
perfectly formed diagrams; and, in
by mor%
to the tighter
condition of the valves and pistons.
One
given that shows the loss in economy due to the
test is
variable load produced in
Engine No. 58 B, which
engine.
Compared with
railway service.
electric
is
Tliis
test
with the same engine working under a steady load, the loss
On
only 2.5%.
is
compound condensing
No. 58 A, which Avas made
a Corliss
is
the test witli the variable load, the average
power was 843.4 H. P., while that with the steady load was
It is evident that the difference in economy
1030.1 H. P.
shown was caused to a considerable extent, if not wholly, by
the fact that in the variable load the engine
loaded, and not working to
its
is
at times under-
economical advantage.
l)est
This was probably an unusually favorable showing for a variable load in the service mentioned, for the reason that the range
of variation
An
was
less
than occurs in
much work
of this kind.
examination of the indicator diagrams gives some idea of
the extent of the variation.
One method
of reducing the loss of
engines are used,
of the engine.
is
to
Tliis
simple engine to a
steam where compound
exhaust the air-pump into the receiver
virtually converts the air-pump from a
compound
engine.
The
izing the exhaust steam of the air-pump
The
effect is
shown by the
is
effect of thus util-
seen in test No. 57.
large increase of the
amount
of
steam accounted for in the low-pressure cylinder, as compared
The increase is from
with that in the high-pressure cylinder.
.696
to .80, or
.104.
In Engine
No
55,
type except in this particular, the increase
which
is
is
of similar
only .013
;
and in
Engine No. 58 A, also similar in type, there is a falling off of
In Engine No. 57, the steam used by the air-pump when
.08.
exhausting into the condenser amounted to .9 of a pound per
;
REVIEW OF FEED-WATER
TESTS.
277
H. P. per hour, and when exhausting into the receiver it
was, of course, a much larger quantity; but in spite of this
I.
the extra
power produced by the use
pressure cylinder was
of the
steam in the low-
such that the entire consumption
the engine and condenser was only 14.1
per
lbs.
1.
of
H. P. per
hour.
One
on a compound engine
test
is
given, where the water
drained from jackets and receiver was
pumped
into
a
flue
heater, and the steam produced by its re-evaporation brought
back to the receiver and used in the low-pressure cylinder.
This
is
Engine Xo. 50.
Under
the circumstances of a compar-
which was 108.1
result obtained, which was 13.28 lbs. per
atively low boiler pressure,
lbs.,
cal
I.
must be considered
H. P. per hour,
The engine, however, was sup-
excellent.
plied with superheated steam
the economi-
;
and
this condition
is,
no doubt,
accountable, in some degree at least, for the result obtained.
It is
doubtful whether the re-heating had any marked effect
because
it
cylinder
is
appears that the steam accounted for in the L. P.
.77 as against .889 in the
H. P. cylinder, showing a
between the two of .119. If this is compared with Engine
No. 49, which is supplied with ordinary steam, and had no
re-heating feature, there is a difference between the two cylin-
loss
ders of .106
;
more loss in this case between
Engine No. 50, which had the re-heating
so that there is no
the cylinders than in
system.
The evidence
of the tests furnish
some data upon the
compound
of varying
the receiver pressure in a
this data is
not conclusive as applied to other engines.
case of Engine No. 51, three tests
made with nearly
load and with a receiver pressure, ranging from 5.4
the atmosphere to 12.9
lbs.,
the
cut-off in
effect
engine, but
In the
the same
lbs.
above
the low-pressure
cylinder being gradually shortened as the pressure increased,
showed a gradual reduction in the feed-water consumed per
With the lowest pressure, it was 12.29 lbs.,
I. H. P. per hour.
and with the liighest, 11.89 lbs. In Engines No. 47 and 52,
were made with three different receiver
pressures, practically the same result is produced at the two
where similar
tests
27
ENGINE
('
extreme pressures.
TESTS.
In one case, the intermediate jjressure gave
a slight reduction, whereas in the other, the intermediate pressure gave a slight increase in the consumption.
IN CONCLUSIOK.
A
careful study of these tests should be of service to engi-
neers in designing
much
new
plants or re-organizing old ones, inas-
as they show, within the limits covered, what designs
and practices should be avoided, and what conditions should be
observed in order to secure desired results in the best manner.
YAI.VE
SETTIIS^G,
279
ENGINE
No. 61.
Double valve, 6" x 14'^ Speed, 210 revolutions per minute.
This is an automatic cut-off engine with slide valves and
The main valve is of the box pattern, with
shaft governor.
balance plates on the back face.
interior of the
cylinder.
box before
The
cut-off
it
Steam
valve rides on
operated by a separate eccentric, which
of a shaft governor.
moving the
is
admitted into the
passes through the ports into the
a seat inside, and
is
shifted
is
by the action
The diagrams here given show
the effect
which operates the main valve an
This represents a disangular distance of 43° on the shaft.
of
tance of
before,
IV
eccentric
on a shaft 4" in diameter.
and No. 616
after, the
change.
ENGINE No. 61a
281
No. 61a was taken
ENGINE
Pour
valve, 16"
x 48".
No. 62.
Speed, 82 revolutions per minute.
is of the 4-valve type, the steam valves being
and the exhaust, Corliss valves. They are operChanges in the setting of the
ated by separate eccentrics.
valves consisted in moving the steam-valve eccentric ahead
2" measured on the circumference of the 8" shaft, moving the
This engine
slide valves,
exhaust eccentric ahead. |", adjusting the tappet which operates
the steam valve so as to obtain earlier admission, and shorten-
ing the exhaustrvalve rod two turns to obtain earlier release.
The diagrams were taken from
and No. Q2b
after, the
the head end. No. 62 a before,
change.
In connection with these changes feed-water tests were made
which showed a saving of 8 % on the steam used by the plant
of which this engine formed a part; the total power of the
plant being
by
somewhat more than twice the power developed
this engine.
ENGINE No. 62a
ENGINE No. 62b
ENGINE
Four valve
(Corliss), 18"
No. 63.
x 48'^
Speed, 57 revolutions per
minute.
This engine
tric.
is of
the ordinary Corliss type with single eccen-
The changes
in
the valves
consisted
in
moving the
eccentric forward ^ inch on a 10'' shaft, and shorteninof the
steam-valve rod 4 turns, or 4 threads.
The diagrams were
taken from the head end, No. 63a before, and No. 635
the change.
ENGINE No. 63a
ENGINE No. 63b
283
after,
ENGINE
Four valve
(Corliss),
No. 64.
23" x 48".
Speed, 51 revolutions per
minute.
The steam-valve rod was lengthened 6 turns, or 6 threads,
The diagrams are from the crank end,
the lead.
to reduce
No. 64a being taken before, and No. 646
ENGINE No. 64a
ENGINE No. 64b
284
after, the
adjustment.
ENGINE
Four valve
(Corliss),
IV
No. 65.
x 36 '\
Speed, 67 revolutions per
minute.
was moved forward |" on the 7" shaft. The
The diasteam-valve rod was shortened 6 turns or 6 threads.
grams are from the head end. No. Q5a being taken before, and
The
No. Q5b
eccentiic
after, the
change.
ENGINE No. 65a
285
ENGINE
Four valve
(Corliss), 26"
x
No. 66.
60".
Speed, 51 revolutions per
minute.
The changes
in the valve-setting
eccentric forward |"
on the
consisted in
12'^ shaft
moving the
and shortening the ex-
haust-valve rod 2^ turns, or 5 threads, so as to secure earlier
release.
The diagrams
are
from the head end of the cylinder.
No. 66a being taken before, and No. 66h
ENGINE No. 66a
after, the
change.
ENGINE
Single valve, 8" x 10".
This engine
ernor,
shifting
is
No. 67.
Speed, 326 revolutions per minute.
of the automatic cut-off type with shaft gov-
eccentric,
and balanced
slide
These
valve.
diagrams show the effect of unequal adjustment of the lap of
the valve.
The
engine loaded.
is
first
set,
The mean
67^ and 67b, was taken
effective
8 lbs., and at the crank end,
o2A
Avith
the
pressure at the head end
lbs.
The second
set,
61c
and 61d, was taken with a friction load. Here the mean effective pressure at the head end is a minus quantity, and at the
The third set, 61e and 67/", was
crank end a plus quantity.
taken under the same conditions of load as the second, after
equalizing the lap.
With
this
adjustment the mean effective
pressure at the head end was 1.9
lbs.,
and
crank end,
at the
3.4 lbs.
ENGINE
No. 67a
30
Head End
20
-10
-
ENGINE No. 67b
-60
-50
Crank End
-40
30
-20
-10
-
287
ENGINE No. 67c
30
Head End
20
10
-
ENGINE No. 67d
O
70
60
50
Crank End
40
30
20
-10
ENGINE No. 67e
30
Head End
20
10
ENGINE No. 67f
-40
30
Crank End
-20
-10
-
ENGINE
Four
valve, 13''
x 36".
No. 68.
Speed, 61 revolutions per minute.
This engine has double poppet valves for admission, and
The valves are operated by a train
and cams. The adjustments consisted in moving forward the cam which operates the steam valve so as to produce
The diagrams are taken from the head end,
earlier admission.
slide valves for exhaust.
of gears
No. 68a before, and 686
after, the
changes.
ENGINE No. 68a
ENGINE No. 68b
289
ENGINE
Four
valve,
IV x
30".
No. 69.
Speed, 80 revolutions per minute.
This engine has double-poppet admission valves, and
valves for exhaust
;
all
slide
driven by a train of gears.
The steam-valve cam was moved forward i" on its
The diagrams are taken from
the exhaust cam |".
shaft,
end. No. 69a before, and No. 696 after, the adjustments.
ENGINE No. eSa
ENGINE
No.
69b
290
and
the crank
ENGINE
Four
valve, 18''
x42".
No. 70.
Speed, b5 revolutions per minute.
In this engine the steam valves are double poppet, and the
slides.
The mechanism is driven by means of
The
adjustment
of the valves consisted in moving
bevel gears.
the driving-gear forward on the shaft two teeth.
The total
number of teeth on this gear was 44. The diagrams are from
exhaust valves,
the head end. No. 10a being taken before, and No. 706 after,
the changes.
ENGINE No. 70a
ENGINE No. 70b
291
ENGINE
Four
valve, 14" x 35".
No. 71.
Speed, 49 revolutions per minute.
This engine has two double-poppet steam valves, and slide
valves for the exhaust;
The changes
all
driven through a train of gears.
consisted in moving the stem of the steam valve
and setting the gear forward
The diagrams were taken from the head
and No. lib after, the adjustments.
in so as to clear the driving-cam,
on the shaft 2 teeth.
end. No. 71a before,
ENGINENo. 71a
ENGINE
No. 71b
292
ENGINE
Four
valve, 16''
x36".
No. 72.
Speed, 72 revolutions per minute.
This engine has two double-poppet steam valves, and slide
valves for the exhaust.
They
are driven through a train of
gears.
The gear which
drives the valves
was changed, with a view
up to the initial
to securing compression of the exhaust steam
moved forward, thereby hastening the release
This change was made with the
studying the effect of compression upon the actual
pressure, being
as well as the compression.
object of
economy of the engine under conditions of practically the same
load.
So far as this test showed anything, under these conditions, there was in reality a slight increase in the amount of
feed-water consumed per horse-power per hour, attending the
The diagrams were taken from the crank
earlier compression.
end, No. 12a before, and No. 12b after, the change.
ENGINE No. 72a
ENGINE No. 72b
293
ENGINE
Four valve, 26'^ x48''.
The steam valves in
No. 73.
Speed, 50 revolutions per minute.
this
engine are slide valves, and the
exhaust are Corliss valves.
'J'he
change here consisted in moving the driving-gear for
the steam valves one tooth
ahead, the total
number being
42,
and in shortening the exhaust rod so as to reduce the lap on
the exhaust valve.
The diagrams were taken from the head
end. No. 73a before, and No. 736 after, the changes.
ENGINE No. 73a
ENGINE No. 73b
2d4
ENGINE
Four
valve, 18" x48''.
No. 74.
Speed, 64 revolutions per minute.
All the valves in this engine are slides driven by double eccentrics.
valve
The adjustments
eccentric 1^'^
on the
consisted in advancing the steam9''
shaft,
and the exhaust eccentric
The diagrams were taken from the head end. No.
^ inch.
7ia before, and No. 745 after, the changes.
ENGINE No. 74a
ENGINE No. 74b
295
ENGINE
Four valve
minute.
The
(Corliss), 30''
No. 75.
x 48/'
setting of the valves
Speed, 80 revolutions per
was changed by the
intro-
duction of a separate eccentric for driving the exhaust valves,
and the adjustment
compression.
With
unsatisfactorily on
of
a
this
single
eccentric
so as to obtain
eccentric
the engine
early
operated
account of the noisy action of the piston
and valves, there being decided and annoying sounds at each
end of the stroke, which could be distinctly heard by a
person standing at a distance of 20 feet from the cylinder.
When the additional eccentric had been applied and the valves
readjusted, the troublesome sounds so far disappeared that
was necessary
for the
it
observer to hold his ear close to the
cylinder to be aware of any disturbance.
The diagrams were
taken from the head end, and for ready comparison, they are
superimposed, the
and the dotted
being taken with single eccentric
changing to double eccentrics and re-
full line
line after
setting the valves.
ENGINE No. 75
296
ENGINE
Four valve,
20"'
x 50/'
No. 76.
Speed, 64 revolutions per minute.
This engine has four slide valves,
curiosity,
all
operated by means of
The diagram here given
a train of gears.
showing the
effect
of
admission
is
of
presented as a
steam to the
cylinder subsequent to the cut-off, due to the rebounding of
the valve after
it
had once
from the crank end
closed.
of the cylinder.
ENGINE No. 76
297
The diagram was taken
ENGINE
Elevator Engine,
This
is
8'^
No. 77.
x 10/'
introduced as a curiosity, and at the same time
reveals the wasteful character of this class of engine.
is
it
There
an absence of expansion and exceedingly high back pressure,
both of which are required by the exigencies of the service and
type of valve mechanism which that service necessitates.
diagram also
illustrates the effect of
indicator on the cylinder.
This
improper location of the
In this case
it
was placed
at a short
distance from the end of the stroke, so that the piston ring
it had moved a certain distance on
The hump on the diagram is caused by
covered the hole until
forward stroke.
defective location.
The diagram was taken on an upward
ENGINE No.77
298
trip.
the
this
ENGINE
No. 78.
Four valve (Corliss), 23'^ x 60/' Speed, 74 rev. per min.
These diagrams furnish another instance showing the influence, or want of influence, of leakage.
In this case the
Diagram No. 7Sa was taken with
trouble was with the piston.
the piston leaking, the packing ring being broken, and No. 786
was taken when the ring had been renewed, and the piston
Feed- water tests made under both conditions
made tight.
showed that the leaking engine used 34.5 lbs. of steam per I. H.
The difference is
P. per hour, and the tight engine, 27.7 lbs.
about 20 %. The boiler pressure was higher after the repairs
than before, but this does not affect the general features.
So
far as the expansion line
had no appreciable
is
effect.
concerned, the leakage of the piston
There
is
a noticeable difference in
the compression lines, but in the leaking engine this alone
would not prove the leakage
from the crank end.
in question.
The diagrams
ENGINE No. 78a
/
-60
40
20
80
ENGINE No. 78b
60
-40
20
^
299
are
ENGINE
Four valve
(Corliss), cross
No. 79.
compound,
24''
and 44''x 72/'
Speed, 61 revolutions per minute.
The main
object in changing the adjustment of the valves in
this engine was to secure a greater amount of compression, and
Previous to the changes
a more quiet operation of the engine.
there was considerable knocking in the main connections when
the centers were passed, and internal noises in both cylinders.
The effect of the changes was to almost wholly overcome these
The adjustments consisted
defects in the running qualities.
in
moving the
yg^"
eccentric of the high-pressure cylinder forward
on the 12" shaft and the eccentric of the low-pressure
cylinder forward 1^."
The steam-valve
rods of the high-pres-
sure cylinder were both shortened two threads, so as to give
earlier admission.
The exhaust rods
of the
same cylinder were
lengthened 8 threads each, so as to increase the compression.
The steam-valve
rods of the L. P. cylinder were shortened three
and the exhaust
lengthened 6 threads, so as to obtain earlier com-
threads each, so as to give earlier admission
rods were eacli
pression.
To
;
l)etter reveal the effect of the
changes, the diar
grams are superimposed, the dotted lines being taken
and the full lines after, the adjustments.
300
before,
ENGINE No. 79
loo-
se
H.P.
Head End
60H
40-
20
0-
-!00
H.P. Crank End
-
80
60
-40
-
•-
20
O
15
l^.P.
Head End
10
5
-
5
10
16
L.P.
Crank End
t- iO
5
G
10
ENGINE
No. 80.
Four valve (Corliss) tandem compound,
18"'
and
30"'
x 48"^
Speed, 63 revolutions per minute.
was operated by
double eccentrics.
The diagrams here given show the effect
produced by advancing the eccentric which drives the exhaust
The low-pressure
cylinder of
this engine
valves of the low-pressure cylinder S^'on the 12'' shaft.
At
the same time the exhaust rod on the high-pressure cylinder was
lengthened 2 threads, so as to give greater compression.
The
diagrams were taken at the head end of both cylinders, No.
80^ before, and No. 806
after, the
adjustments.
ENGINE No. 80a
120-1
100-
80-
H.P. Cyl.
60H
40-
20H
0-
UP.
Cyl.
r
'^
-
10
5
O
5
10
ENGINE No. 80b
120-
100
80
H.P. Cyl.
60H
4020-
r
L.P. Cyl.
15
iO
5
5
10
ENGINE
No. 81.
Compound duplex direct acting pumping engine.
These diagrams show the effect of increasing the throw of
the valves (which are slide valves), thereby giving the engine
the benefit of wider
shown mainly
pressure cylinder.
formed by the
The
effect of the
pump was
was much reduced.
after, the
opening of ports.
The improvement is
vacuum in the low-
in the increased effect of the
change on the duty per-
marked, and the consumption of coal
No. 81a was taken before, and No. 815
change.
ENGINE No. 81a
304
I
ENGINE
Four valve
cross
75 revolutions
The
type.
j)er
compound,
No. 82.
24'"
and
46'"
x 48'^
high-pressure cylinder of this engine
The low-pressure
adjustable by hand.
is
of the four- valve
cylinder has slide valves with cut-off
These diagrams show the
distribution of the load between
effect
I
mark.
it
was
set at the i mark,
and the
other.
upon the
produced by
the cylinders
changing the cut-off in the low-pressure cylinder.
No. 82 a,
Speed,
minute.
In one case.
No. 825, at the
In the former the power developed by the high-pressure
cylinder was 408 H. P., and by the low-pressure cylinder 300
H.
P., while
480 and 222.
in the latter, the quantities
The diagrams
were
respectively
are from the crank end.
306
ENGINE No. 82a
r-lOO
80
H.P. Cyl.
60
1-40
20
L.P. Cyl.
-
10
—
5
I- 5
10
ENGINE No. 82b
100
H.P. Cyl
80
l_
60
40
-20
—
L.P. Cyl.
I-
6
10
i
ENGINE
No. 83.
Canadian cross-compound engine,
20""
and
36''
x
42''.
Speed,
76 revolutions per minute.
The
high-pressure cylinder in this engine has Corliss valves
and the usual automatic
The low-pressure cylinder has
cut-ofT.
a plain slide valve with no means of adjusting the cut-off save
by shifting the eccentric. These diagrams show the effect
upon the distribution of the load between the cylinders produced by changing the low-pressure cut-off by the eccentric
adjustment.
When
the
steam followed in the low-pressure
cylinder to nearly full stroke No. 83 «, the power developed in
the high-pressure cylinder was 167 H. P., and in the low-pres-
sure cylinder, 60 H. P.
the
low-pressure
When
cylinder,
the eccentric
was advanced
in
No. 836, these quantities became
respectively 149 H. P. and 80 H. P.
307
ENGINE No. 83a
60
H.P. Cyl.
40
20
L.P. Cyl.
ENGINE No. 83b
^60
-40
H.P. Cyl
- 20
1—
L.P. Cyl.
r
°
-
6
-
10
ENGINE
No. 84.
Four-valve cross compound, 17^' and 28'' x
48''.
Speed,
100 revolutions per minute.
This engine
The valves are
a non-condensing compound.
and the steam and exhaust are operated by in-
is
all slide valves,
dependent eccentrics.
The diagrams show
the effect produced
by changing the cutoff on the low-pressure cylinder, and thereby the pressure in the intermediate receiver. Diagram 84 a
was taken with a receiver pressure of 44 lbs., and diagram
84 h with a receiver pressure of 27^ lbs. They are all from the
crank end.
309
ENGINE No. 84a
-120
H.P. Cyl.
-100
-30
'60
-40
-20
U-
4030L.P. Cyl.
2010-
0-^
ENGINE No. 84b
-120
-100
H.P. Cyl.
80
-60
-40
20
-
30n
2010-
0-'
L.P. Cyl.
ENGINE
No. 85.
Four-valve (Corliss) cross-compound,
24''
and
34''
x 48".
Speed, 61 revolutions per minute.
In this engine the governor operated on the cut-off of the
high-pressure cylinder.
The
cut-off of the low-pressure cylin-
der was under the control of a pressure regulator set so as to
maintain a constant pressure in the receiver, irrespective of the
load or other conditions.
Steam was withdrawn from
receiver for heating purposes
;
in
this
this
case for the heating of
which supplied the engine,
and the diagrams given were taken under two conditions of
running
first, No. 85 a, when all the
steam was used for
power, and second. No. 856, when the steam was withdrawn
from the receiver as noted.
feed- water for the plant of boilers
;
311
ENGINE No. 85a
i-lOO
80
H.P. Cyl
60
-40
20
r- 10
L.P. Cyl
6
—
—
5
-10
ENGINE No. 85b
HOG
-80
H.P. Cyl
60
t-40
20
>—
r-IO
UP.
5
Cyl.
O
-
6
— 10
;
ENGINE
No. 86.
Four-valve cross compound, 20" and
36''
x
48''.
Speed, 65
revolutions per minute.
The condenser
injection
water
steam pump.
of
is
This
engine
this
is
the siphon type, and the
supplied by an independent directracting
is
arranged
so as
to
exhaust into
the
The diagrams given
were taken under both of these conditions of running the pump
those with the full lines being taken when the pump was exreceiver or into the emidenser, as desired.
hausting into the receiver, and those with dotted lines
when
same was turned into the condenser. The comparatively
is due to the air leakage through the
packing around the valve stems and piston rod of the pump.
the
poor vacuum in the latter
ENGINE No. 86
-100
80
60
40
20
15
^-^
/
L.P. Cyl.
//
/
y/
^—
^^^^^
'
10
.-''"'
- 5
-
^"^
6
rrrrrrrr:^^^
10
81.3
ENGINE
No. 87.
Single-valve cross compound, 15" and
23" x 15".
Speed,
260 revolutions per minute.
This engine has unpacked piston valves, one for each cylinder,
with a shaft governor operating on the high-pressure valve.
These diagrams are given to show the
the casting
of the
effect of a break in
high-pressure steam-chest, which allowed
steam to pass directly into the low-pressure chest without going
The two
through the high-pressure cylinder.
chest were
all
made
in one casting.
Sib were taken with a load of 79.5
87(^ with
a load of 131.1,
I.
H. P.
I.
cylinders and the
Diagrams No. 87a and
H. P., and No. Sic and
In the former the low-
pressure cylinder develojjed 155.2 H. P., and in the latter 141.3
H. P.
In the former the high-pressure cylinder produced a
power equivalent to 75.7 horse-power,
this was reduced to 10.2 horee-power.
The
resistance or negative
while in the latter
difference in these quantities gives the respective horse-powers
is
In
stated.
as
diagmm Sla
the
the steam and expansion line,
and the lower line
is
the one that
upj)er line,
is
is
which
oi-dinarily
here the compression line,
made during
the admission,
expansion, and release.
The
the compression of the
exhaust carries the back pressure up
to
120
lbs.
ning of the
boiler pressui-e here
is
75
lbs.,
and
The point of cut-off takes place at the very beginstroke, and evidently there is no steam admitted
save that which comes from the compression of the exhaust.
Diagrams 87(' and 87/ were taken from an engine of the
same size and make, in which there was no defect such as that
mentioned and a comparison with these will show the effect
produced by the disordered condition. In these diagrams the
high-pressui'e cylinder develojjed 71.4 I. H. P., and the lowpressure 53.3, making a total for the engine of 124.7 I. H. P.
This is about the same power as that shown by diagrams Sic
;
and
87(7.
These diagrams are
all
from the crank ends.
314
ENGINE No. 87a
— 100
80
—
60
40
— 20
25-
ENGINE No. 87b
20-
L.P. Cyl.
1510-
5-
0-\
6-
lO-l
ENGINE No. 87c
- 40
H.P. Cyl.
20
1-
ENGINE No. 87d
L.P. Cyl.
ENGINE
No. 87e
60
40
20
ENGINE
No. 87f
L.P. Cyl.
0610-
ENGINE
Marine
triple
No. 88.
expansion engine,
15'',
23'',
and 40" x 30".
Speed, 83^ revolutions per minute.
These diagrams show the
effect
low-pressure piston.
The dotted
gram
when
is
the one taken
full line the
produced by leakage of the
on the low-pressure dia-
line
the leakage was going on, and the
one taken with a tight piston.
The diagrams S8a
from the intermediate and high-pressure cylinders are those
The effect of stopping the leaktaken with the tight engine.
age,
which was due to the weakness
of the springs
under the
packing-rings, was to raise the pressure in the receiver.
was 4
The
Another effect was to increase the speed
of the engine when running at full capacity from 81 revolutions
per minute to 84. Still another effect was to increase the power
developed from 410 I. H. P. to 442 I. H. P.
increase
lbs.
ENGINE No. 88a
H.P. Cyl.
140120100-
80604020-
ENGINE No. 88b
L.P. Cyl.
lOJ
317
'
ENGINE
Compound
12''.
No. 89.
high-speed non-condensing eiigme,
and
12''
x
Speed, 201 revolutions per minute.
These diagrams are given simply as
pressure cylinder
tions
6''
is
doing nearly
under which the steam
as could occur.
There
is
no
der; the terminal pressure
diagram, the release
pressure diagram
is
is
is late,
all
curiosities.
The
high-
the work, and the condi-
distributed are about as wasteful
cut-off in the high-pressure cylin-
any part of the
and the back pressure on the lowis
the highest of
excessive.
— 60
— 40
20
•—
L.P. Cyl.
- 40
- 20
318
ENGINE
No. 90.
Diagrams 90 a and 90 h are introduced partly as curiosities
and partly to show the general features of diagrams obtained
from a steam-driven air-pump operating an independent con10^'
Here the cylinder was
denser.
when the pump exhausted
gram 90^ when it exhausted into
taken
liarity of these
steam at
full
diagrams
lies in
x 10'^
Diagram 90 a was
and diathe atmosphere.
The pecuinto the condenser,
the fact that the
pump
takes
stroke, exhausts at a higher pressure than the
pressure of admission
and the return stroke
;
is
made, for a por-
under the wasteful conditions of a very high back
Another curiosity is the stopping of the piston at
about the middle of the stroke, and the rebounding of the same
tion at least,
pressure.
before
it
When
proceeds on
this
course.
its
pump was running
non-condensing the exhaust
steam was measured by collecting and condensing
of water.
It
was found
717
to use
lbs. of
speed of 61.2 double strokes per minute, or 103.3
per
I.
it
in a barrel
steam per hour, at a
lbs. of
steam
H. P. per hour, the power developed being 6.94 H. P.
This performance represents, as might be expected, a very
wasteful use of steam
proj^erly arranged
warming
;
but
the heat
the feed-water,
it
should be stated that in a plant
the steam can be utilized in
of
and the
tively small quantity.
319
loss is
reduced to a compara-
ENGINE
No. 90a
Head End
r-40
20
Crank End
40
-20
ENGINE
No. 90b
Head End
40
20
"-
Crank End
-40
20
STE^VM-PIPE DIAGEAMS.
321
STEAM-PIPE DIAGRAMS.
The
which a running-engine has upon the pressure in
shown by an indicator diagram taken from
the pipe, is a matter which not only possesses interest from an
engineering point of view, but it has a bearing on an important
effect
the steam pipe, as
question relating to steam-pipe design.
The
fluctuations of
pressure in the pipe caused by the intermittent flow of steam
into an automatic cut-off engine
is sufficient
to set
up
vibrations
and these extend from the engine through the
whole distance back to the boiler unless the pipe is well anchored, and sometimes in spite of what appears to be good
anchorage.
When we consider the relatively small weight of
the substance which is traveling through the pipe, it is difficult
to realize the powerful effect which these fluctuations have upon
its stability.
It is not, however, the substance itself which is
in the pipe
;
the potent factor in the matter, but the effect of the unbal-
anced pressure acting between the two ends of a section of pipe
produced by the sudden and intermittent reduction of pressure
at the
end nearest the engine.
the diameter of the pipe
of
10
lbs.
is 8'',
If the
there
is
reduction
is
10
lbs.
and
an unbalanced pressure
per square inch upon an area of about 50 square
500 lbs. acting in the direction of the
Such a force would have in a measure
the effect of a 500 lb. blow upon the pipe, which, of course, is
a serious matter.
These fluctuations can be overcome to some
extent by avoiding short right-angle elbows, and employing
long-turn bends in their place.
They can be overcome more
inches, or a total force of
length of the section.
effectually by introducing in the steam pipe as near as possible
to the engine a reservoir
having considerable volume relative
to the size of the cylinder,
and passing the steam through the
large space thus provided.
The
323
fluctuations will then occur
324
ENGINE
TESTS.
mainly in that part of the pipe which lies between the reservoir
and the cylinder, and the reservoir serves to prevent them to a
large extent from extending back to the boiler.
pipe diagrams here given
some means
show
The steam-
the desirability of employing
for reducing the extent of these fluctuations,
in one instance the beneficial effect of a reservoir
revealed.
is
and
clearly
ENGINE
No. 91.
Diagrams 91a and 916 were taken from a 9'' steam pipe
supplying a 28'' x 48'' Corliss non-condensing engine running
The pipe is a
at a speed of 100 revolutions per minute.
branch from a long 12" pipe leading to the boilers, and its
length measured from the 12" is about 30 feet.
The pipe
Diagram 91« is comand reveals the
contains 6 short right-angle elbows.
plete for the entire revolution of the engine,
pulsations
cylinder.
produced by the admission at both ends
Diagram 91h
relates to
one stroke.
The
the
indicator
diagram from the cylinder taken on the same stroke
.
of
is
also
shown.
so-
so
ENGINENo.Qla
40-
20080-,
60
40-
20-
It will be seen that just before the beginning of the stroke
the pressure in the steam pipe drops
;
and
constant until the cut-off takes place,
325
it is
when
it
maintained nearly
immediately
rises.
326
ENGINE
TESTS.
Afterwards the pressure gradually
falls,
and a short time before
the opposite end of the stroke
is
reached
quently when
is
reached
the very end
it rises
it
again.
falls
Subse-
abruptly, co-
incident with the admission of steam to the otlier end of the
cylinder.
ENGINE
No. 92.
Diagrams 92a and 92b are from an 8'' steam pipe supplying a 23'' X 60'' non-condensing Corliss engine running at
a speed of 75 revolutions per minute.
in length
The
measured from the nearest boiler
is
82 feet
to the
throttle
pipe
Diagram
valve, and it contains 5 short right-angle elbows.
92a applies to a complete revolution, and 92b simply to
the forward stroke taken while the piston was moving from
80
-60
ENGINENo.92a
-40
20
^
80
-40
-20
the head end of the cylinder.
The indicator diagram from the
head end of the cylinder is also given. Referring to the latter,
it
appears that just prior to the beginning of the stroke the
pressure rises in the steam pipe.
ment
of the piston
Coincident with the move-
forward during the admission, the pressure
in the pipe gradually falls
up
to the point of cut-off,
this occurs it rises to a point
some 10
327
lbs.
and when
above the line of
ENGINE
328
At
average pressure.
a point just beyond the middle of the
stroke the pressure gradually
of
the forward stroke
TESTS.
it
falls,
suddenly
until just before the
end
rises again preparatory to
the beginning of the return stroke.
This diagram
rises at the
is
a curiosity for the reason that the pressure
very beginning of the stroke, when presumably the
taking steam, whereas under the ordinary circumwould
stances it
be expected that the operation would be
The probability is that
reversed and the pressure would fall.
owing to the compression of the exhaust steam into the clearcylinder
is
ance space the quantity of live steam admitted
is
very small.
Another curiosity in this diagram is the fall of pressure
from the middle to nearly the end of the stroke. During this
period there is no steam being drawn out of the pipe, and the
only explanation of this action
is
the assumption of a sort of
rebounding of the steam within the pipe due to the intermittent character of the flow.
In this matter as well as in the
conformation of the diagram throughout, there are
which, to say the
least, are obscui-e.
many
points
ENGINE
This diagram
densing engine,
is
7''
from a
32'^
x
No. 93,
pipe supplying a
con-
Corliss
making 47 revolutions per minute.
54'',
The engine diagram given
from the crank end of the
cylinder, and the steam-pipe diagram refers to one stroke of
the piston, that
is,
is
made from
the one
the crank end to the
This engine was one cylinder of a pair, and the
steam pipe consisted of a 10" main leading from the boilers
and a 7" branch to each cylinder.
The distance from the
front end.
10" to the throttle valve was
right-angle elbows.
the diagram
20
and
feet,
The other cylinder was
it
contained two
in operation
when
was being taken.
80-1
60-
On
the steam-pipe diagram
just before the beginning of
it
it
appears that the pressure rises
tlie
stroke,
and immediately
after
drops back to nearly the same point, and remains nearly con-
stant until the steam
rises.
is
cut off from the cylinder,
Just before the middle of the stroke the pressure
again, this action being
due presumably
taking steam, followed by another
the
when
time of the cut-off in
it
falls
to the other cylinder
rise in the
pressure at about
the other cylinder.
Just prior to
the beginning of the return stroke the pressure rises as before,
and again drops soon after the beginning
the other end of the cylinder begins
when
329
of the return stroke,
to take steam.
EITGINE TESTS,
330
Here
another curiosity.
is
At
the very beginning of the
steam-pipe diagram the pressure increases in a marked degree
at the
time
when
apparently the cylinder begins to take steam,
and then immediately drops back.
is difficult
of explanation.
The reason
for this action
ENGINE
No. 94.
Diagram No. 94 is from the steam pipe of the right-hand
cylinder of a pair of double-valve engines, 17^' x 24'^ running
at a speed of
154 revolutions per minute.
-60
ENGINE No. 94
-40
20
—
The main pipe here was 140
feet in length, 10'^ in diameter,
and had 3 short right-angle elbows. The branch pipe for the
two cylinders were each 6'' in diameter and 8' in length, and
each contained 2 right^angle elbows. This is the same engine
as that referred to as No. 10 in the section on Feed-Water
Tests, but it was taken with an indicator having a different
scale from the diagrams given in connection with the results
of those tests.
It
win be seen
in this diagram that the effect of the closing
of the valves at the points of cut-off are clearly revealed,
that in other 1-espects
defined.
rapid,
Considering that the reciprocations are somewhat
and that the diagram shows the
tions produced
study of
but
the various operations are not clearly
its
by both
cylinders, it
various features.
331
is
effect of the fluctua-
difficult to
make
a close
ENGINE
Diagram No. 95
is
No. 95.
from the steam pipe of a 20" x
5C
four-
valve engine making 65 revolutions per minute.
70
-60
-60
40
30
20
10
The pipe
is
b" in diameter and 36' long, and
it
contains 4
same engine as the one
numbered 76 under the head of Valve Setting. The features
in this diagram conform in the main to what would be expected
from the known operations of the steam. The pressure drops
at the beginning of the stroke, and rises at the point of cutoff
and when the opposite end of the stroke is reached it drops
This
short right-angle elbows.
is
the
;
again, coincident with
rises again
when
feature here
is
opening of the steam valve, and
the
the cut-off at the other
noticeable
and that
;
is,
end
ttikes place.
One
that the effect of the
subsequent admission after the cutroff, which is shown on the
diagram taken from the cylinder, the same as in No. 76, is
clearly revealed on the steam-pipe diagram, where there is a
second
fall
of pressure just
beyond the point where the
occurs due to the regular cut-off.
The
fall
of pressure
rise
com-
mencing at the middle of the stroke and continuing to near the
end is a feature of this diagram the same as in some of the
preceding ones which have been referred to, though here it
takes place more gradually than in some.
332
.
ENGINE
No. 96.
Diagrams 96a and 966 are from the head end of a Corliss
condensing engine, 20" x 48" running at a speed of 60 revolutions per minute.
100
80H
60-
40
20H
010
lOOn
80
60-
4020-
lO-l
This engine
taken, the
is
one of a pair
;
but when these diagrams were
second cylinder was out of use, and the throttle
The main pipe here is 10'' in diameter and 33'
The branches are 6" in diameter, and the one lead-
valve closed.
in length.
10' in length, and that to the
ing to the left-hand cylinder
is
right-hand cylinder 15'
length.
in
Each of these branches
The diagrams were taken
Diagram 96a was taken when the
has two short rightrangle elbows.
from the left-hand cylinder.
steam was passing through the pipe above referred
333
to.
When
;
ENGINE
334
TESTS.
diagram 96b was taken the 10" pipe was shut
off at the boiler
end, and steam was furnished through twenty-five feet of 8" pipe
and one 45 degree elbow into a tee at the boiler end of the 10'^
main.
In both these diagrams the admission of steam is accompanied by a drop of pressure in the pipe, as would be expected,
and a corresponding rise of pressure at the point of cut-off. In
diagram 96a the pressure falls again very quickly after cut-off
and a succession of wavy lines occur until the middle of the
stroke,
and then the pressure is nearly constant to the end. In
96^/, on the contrary, the fall of pressure just after the
is much less marked, and there is considerable more rise
diagram
cut-off
in pressure as the
difference in the
end
The only
of the stroke is approached.
conditions under which these diagrams were
obtained was in the lengthened pipe through which the steam
would seem, therefore, that the arrangement of the
to do ^vith the character of the fluctuations.
passed.
It
pipe has
much
It will
be noticed also in
tions resemble in
these diagrams
engines with
previ-
both cylin-
In this case, however, only one cylinder was
running.
in operation.
fluctua-
some respects those which occur on
ous diagrams taken from a pair of
ders
that the
Here
is
another indication that the arrangement
of the pipe has
much more
fluctuations than
would
effect
upon the character
at flrst be supposed.
of the
ENGINE
No. 97.
Diagram No. 97 is from a 10'' steam pipe supplying a
X 12" Corliss engine, making 60 revolutions per minute.
30'
80
-60
ENGINE No. 97
40
-20
—
10
The steam pipe
in
108 feet in length from the main header
and
the boiler-room,
it contains five short right-angle elbows.
The
is
fluctuations of pressure here are of
much
less extent
than
any of the preceding diagrams, due in part probably to the
In view of what the prerelatively light load on the engine.
in
ceding diagrams have shown, the real cause of so
may
little
variation
be some peculiar arrangement of the pipes which acted
favorably.
335
ENGINE
Diagram No. 98
a 24" X
taken from an 8" steam pipe supplying
is
48'' Corliss
No. 98,
engine running at a speed
62 rev-
of
olutions per minute.
r-lOO
80
60
40
20
I10
The pipe
is
angle elbows
135 feet in length, and contains 5 short rightand two 45 degree elbows. The lines in this
diagram are very clearly marked.
There
is
a sudden drop in
the pressure jnst at the beginning of the stroke, and there
marked
be
little
end
rise of
variation of pressure
after this time
stroke.
a
to
imtil nearly the
During the very last jmrt
however, the pressure drops the same as noticed
of the
is
There seems
pressure at the point of cut-off.
of the stroke,
in
many
of
tlie
preceding diagrams, although there appears to be no action in
the working of the steam in the cylinder that should cause
This
is
it.
one of the things that makes the reasons for the par-
ticular conformation of steam-[)ipe diagrams obscure.
ENGINE
No. 99.
Diagram No. 99 was taken from a 6'' pipe supplying a 14''
and 26'' X. 42'' compound engine running at a speed of 100
revolutions per minute.
140
120
100
80
60
40
20
I—
The length
of the
pipe was 75 feet, and
Here
short right^angle elbows.
it
contained two
another case where the lines
is
diagram are clearly marked, and there can be no miscon-
of the
ception in regard to the action going on in the pipe.
gram
is
similar to the one
general features.
is
practically
sion.
There
which precedes
is this
it,
This dia-
and has the same
peculiarity, however, that there
no drop of pressure during the period
The drop occurs toward
of admis-
the very end of the previous
and prior
stroke.
Subsequent to the
pressure
is
given
from the head end, and refers simply to the high-
is
cut-off
well nigh constant.
pressure cylinder.
337
The
to this drop, the
indicator diagram here
ENGINE
Diagram No. 100
No. lOO.
refers to a case
where a reservoir was
and the dia-
installed in the steam pipe close to the cylinder,
The engine is a Corliss
this reservoir.
30" X 48'^ running at a speed of 80 revolutions per minute.
gram was taken from
The receiver is supplied from an 8'' pipe 223 feet in length,
which contained six short right-angle bends, while the engine
12' long,
is supplied from the reservoir through a 10'' pipe
containing two short
reservoir
is
42"
right-angle
in diameter
and
8'
elbows.
The
size
of
the
in height.
roo-,
80-
ENGINE No. too
60-
4020
0-j
10
In this diagram the fluctuations of pressure do not seem to
follow the admission and cutting
oft* of the steam to any great
and at the worst they are confined within narrow limits.
The extreme change of pressure from the highest to the lowest
Comparing this Avith the previous insfcince.
is three pounds.
extent,
No. 99, the difference
is
exceedingly marked.
There the change
was some thirteen pounds. If we investigate these
two cases carefully it will be found that the rate of flow of
steam from the boiler to the reservoir is forty-three feet per
second, and in the other case (No. 99) the rate of flow close to
the throttle valve was twenty-eight feet per second.
The conditions as to the speed of the steam and the quantity withdrawn per stroke with reference to the size of the pipe was
of pi-essure
338
ENGINE
therefore
used.
much more
389
No. 100.
severe in the case where the reservoir
It thus appears that
was
with the same conditions of service,
the favorable effect produced by the reservoir
even greater than that here indicated.
would have been
A
'^^mm:::^mm
^
PLEASE
CARDS OR
DO NOT REMOVE
SLIPS
UNIVERSITY
FROM
THIS
OF TORONTO
POCKET
LIBRARY
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