JF - Part 8 - cd3wd408.zip - Offline - TDRI - The Construction Installation and Operation of an Improved Pit

JF - Part 8 - cd3wd408.zip - Offline - TDRI - The Construction Installation and Operation of an Improved Pit
FICHE
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LIEBRARY
A project of Volunteers in Asia
The co-on.
for cs
Published by:
.
.
wn
.
.
.
and wratron
*
of an-roved
Tropical Development and Research Institute
London, England
Available from: The Head
Publications, Publicity and Public Relations Section
Tropical Development and Research Institute
College House
Wrights Lane
London W8 5SJ
Reproduced with permission.
Reproduction of this microfiche document in any form is subject to the same
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Tropical Development
Research Institute
and
Rural Technology
Guide 15
e construction,
installation
and
operation of an improve
it-kiln for charcoal
production
Rural Technology
Guide
addo
15 1986
Contents
Page
The Tropical Development and Research Institute
recommends that charcoal production be carried
out under the guidance of a forestry department
or similar government body, to prevent the uncontrolled exploitation of woodlands for financial
gain.
Introduction
Description of the kiln
List of materials required for construction
the metal cover and inlet/outlet tubes
of
The pit-kiln method described in this guide was
developed in Liberia by the writer, with the assistance of his counterpart, Mr Chekkor David. The
work was performed under a TDRI/ITDG contract
(funded by the Commission of European Communities) as Rural Technology Adviser to the
Partnership for Productivity (PFP/Liberia).
Making the frame
Making the metal cover
Making the air inlet/smoke
plugs
outlet tubes and
Cutting plan
5
Kiln installation
6
Selecting the kiln site
6
Digging the pit
6
Inserting the metal tubes
7
Building the end walls
8
Tools required for kiln operation
9
Kiln operation
10
Preparation of the wood
10
Loading the kiln
10
Lighting the kiln
12
Carbonising the wood
14
Sealing and cooling the kiln
15
Unloading the kiln
16
Storing the charcoal
17
Operation schedule for two pit kilns
18
Labour input for two kilns
18
Figure 1 Improved charcoal pit-kilnconstructional drawing
Figure 2 Sieve-chute
inside
back cover
19
Introduction
This guide describes how to construct, install and
operate a charcoal kiin by digging a pit and using
a cover made with metal sheets. The kiln is
particularly suitable for operations in rural areas
where iocal charcoal makers have only a small
amount of capital to invest and where a plentiful
supply of wood is available near the kiln. It will
produce charcoal more quickly and efficiently than
the traditional pit and earth clamp methods.
The kiln should only be used in areas where there
is sufficient wood for at least 2 months’ continuous operation in order to justify the effort of
digging the pit. The method should not be used
in rocky areas where digging the pit would be
both dtfficult and excessively time consuming.
Under these conditions and where the extra capital Investment can be arranged, the Tropical
Development and Research Institute recommends
the use of a transportable metal kiln. Instructions
tor the constructlon and operation of the TDRI
transportable metal krln are given in Rural Technology Guides 12 and 13.
Description
kiln
of the
The kiln holds around 8 cubic metres of stacked
wood, most of which is contained in a rectangular
pit dug in the ground to a depth of about 1.8
metres. It will produce up to 1 tonne of charcoal
during its 5-6 day operation.
The cover of the kiln is formed using three overlapping stock-sized mild-steel sheets, sprung into
an angle-Iron framework surrounding the top
edges of the prt. The open ends of the cover are
blocked up with mud.
Metal tubes are set into the walls of the prt to
provide 3 arr inlets, 1 smoke outlet, and a steamrelease vent to assist lighting. A constructional
drawing of the kiln is shown in Figure 1 (enclosed
in the back cover:.
Lis% of materials required for the
tionstruction
of the metal cower an
outlet tubes
Material
Angle-iron
Mild-steel
Size
for frame
covering
sheets
Quantity
40x40x5
mm
12.2 m
2 440 x 1 220 x 1.5 mm
3
Flat mild-steel or galvanised steel sheet for making tubes
and plugs
2440x
2
Flat mild-steei bar for making slide bolts and slots to
secure metal covering sheets and for clips to secure
angle-iron framework
40x4
mm
3m
Round mild-steel ba 3r making handles and hooks for
metal covering sheets
12 mm diameter
3m
Mrld-steel bolts or short pieces of rod for assembly of
anglerron frame and for welding on tc? the upper lip
of the framework to retain the sprung metal sheets
30x 12 mm diameter
20
Steel chain to support central metal sheet
2m
1
1220x
1.0 mm
Making
the frame
The rectangular angle-iron frame is used to keep
the metal sheets of the cover in position.
Make up the frame with two pieces of 40 mm
steel angle each 3 660 mm long, and two pieces
each 2 120 mm long. Weld 150 mm lengths of
angle, arranged at 90” to each end of the two
longest sides so that the angle-iron framework
can be firmly clipped together when used. Provide
an arrangement of studs ar\d holes at each corner
to ensure a secure assembly. Code-mark the joints
so that the frame will always be reassembled in
the correct way.
Place the assembled frame on level ground and
insert a metal stake intu the ground halfway along
the outside edge of each of the two longest sides
of the rectangle. This will prevent distortion of
the frame \vhen the mild-stee! sheets are sprung
into place.
aking
cover
the metal
Insert the first mild-steel sheet into the frame
halfway along its length. Locate the remaining
two sheets at each end of the framework allowing
the inner edges of each end sheet to overlap the
centre sheet by 50 mm.
Weld a set of two handles on both ends of each
sheet and weld on the 4 slide-bolt assemblies used
to clip the sheets firmly together as shown in
Figure 1. Make ihe slots large enough to ensure
that the bolts can slide easily in and out, allowing
for the formatron of rust with prolonged use.
To prevent the metal sheets from springing out
of the angle-iron frame, weld six metal bolts or
short pieces of rod (30 mm long x 12 mm diameter) to the top edges of each of the longest side
of the frame. Weld corresponding reference mar!
on the top faces of the metal sheets so that WI
re-assembled the correct positioning can be
assured.
Finally. weld two brackets onto the middle of the
centre sheet so that a length of chain may be
attached to supl>ort the centre of the metal cover
during the operation of the kiln.
g the air inlet/
smoke outlet tubes
and plugs
Make the tubes and plugs from two stock-size
2 440 mm x 1 220 mm x 1.0 mm thick steel sheets
as shown in the cutting plan on p. 5. If available,
flat galvanised steel sheets may be used. Do not
weld galvanised steel as the fumes produced are
hazardous to health. Always use hammered seams
or bolts and nvets for joining this material.
The three air inlet tubes and the short steam
release tube are all 130 mm diameter and are
formed from 448 mm wide strips of metal sheet
by carefuly hammering them into shape around a
suitable fcrmer (e.g. a scrap drive shaft from a
truck or a straight wooden pole). The seams along
the length of the tubes are welded or suitably
flanged by bending and interlocking the edges of
the metal sheet and hammering tightly as shown
in Figure 1. The smoke outlet tube and the two
extension tubes which form the chimney are all
160 mm diameter. These are formed from 548 mm
wide strips of metal sheet. Join shorter lengths
of tubes together to obtain the required lengths,
Weld bolt or rivet a 200 mm wide strip of metal
sheet around ;he outside of one end of the smoke
outlet tube and also at the end of one of the
chimney extension tubes. This provides a means
of joining these tubes together to form the complete chimney assembly during the operation of
the ki!n.
To make the plugs, cut out 4 discs each 120 mm
in diameter and one 150 mm diameter disc. On
the top surface of each of these discs secure
three metal strips 20 mm wide and 120 mm long
at equal distances around the circumference.
Shape the metal strips to enable the discs to be
suspended inside the top ends of the inlet/outlet
tubes to support the mud used to seal the ends
of the tubes during the operation of the kiln.
4
Cutting
plan
2440
E
2 cMox548
--m/q-
- -
B
2040x448
Dl
lOOOX
_ -
-JQ#jJ-
-
_
- - &W+-
A
1840x448
-
- -J9lfV-
-
D
1040x548
H
200 x 548
C
750 x 448
[email protected]
H
200 x 548
(Al! dimensions
include an extra 40 mm where necessary for forming seams)
Reference
No. off
A
2
Air inlet tube approximately
1 800 mm long x 130 diameter
B
1
Air inlet tube approximately
2 000 mm long x 130 diameter
C
1
Steam release tube approximately
D
2
Chimney extension
E
1
Smoke outlet tube approximately
F
4
Insert plugs 120 mm diameter
G
1
Insert plug 150 mm diameter
H
2
-
Connector collars for references Dl and E
J
Description
and size
750 mm long x 130 diameter
tube approximately
1 000 mm long x 160 diameter
2 000 mm long x 160 diameter
Spare material for other requirements.
Kiln installation
Selecting
Choose an
possible to
70 stacked
be available
installation.
the kiln
area with deep firm soil as close as
a plentiful supply of timber. At least
cubic metres of useable wood should
at each kiln site to justify the
On sloprng ground, arrange for the chimney end
of the kiln to be at the highest point. A supply
of water is required at the site for mixing the mud
used In the kiln’s construction and for quenching
any small fires which may occur wnilst unloJdrng
the charcoal.
To avoid flooding rnake sure that the maximum
height of the water table at the site is below the
proposed level of the bottom of the pit.
Digging
the pit
Clear surface growth and forest debris from an
Inserting
tubes
the metal
Dig out the four recess channels half-way along
each of the four walls of the pit. Remove sufficient
soil so that the metal tubes can be inserted into
the channeis with the base of the tubes in line
with the bottom perimeter of the pit and the top
of ihe tubes protruding above ground level at a
point about 30 cm outside the angle-iron
framework.
With the four met& tubes in positron, fill In the
channels with a mud plaster until the original line
of the prt wall IS ret;iired.
Repair any damage to the perimeter oi the top of
the prt with mud, and insert a firm layer of soil
underneath the angle-Iron framework to support
the frame about 3-4 cm above ground level.
Building
the end walls
i
Insert’ the two metal end sheets into position
within the angle-iron framework.
Build up the two end walls with mud and rock to
fill in the spaces between ground level and the
curved ends of the sheets. Insert the short steamrelease tube when building Ihe mud wall at the
chimney end of the kiln. The outer edges of the
end sheets must overlap the mud walls by at least
10 cm.
The final construction of the end walls of the kiln
is achieved by the builder plastering with mud
from inside the kiln.
Allow the kiln to dry out before use. Any cracks
In the mud plaster which appear during this period
should be, plastered over.
Dig sufficient drainage channels around the kiln
to prevent surface vJater from entering 1:he k:iln
during periods of heavy rain.
Keep the metal sheets on the kiln when the unit
is not being used.
Tools
required
for kiln operation
Quantity
Item
Purpose
Chainsaw
and spares
1
Timber
preparation
Cross-cut
saw’
1
Timber
preparation
Bow saw’
1
Timber
prepararion
Axe’
2
Timber
preparation
Machete
2
Timber
preparation
Wedge
2
Splitting
oversize timber
Sledgehammer
1
Splitting
oversize timber
Shovel
2
Unloading
charcoal
Spade
Digging
pit
Pickaxe
Digging
pit
Bucket
Carrying
spots
water for mixing
Sieve
2
Separating
fines
Flat file
1
For sharpening
‘When
cutting
wood by hand
mud and quenching
fsrger pieces of charcoal
wood preparation
hot
from dust and
tools
Kiln operation
Preparation
wood
of the
Experience has shown that the size of timber used
in the pit kiln affects the performance of the
process. The following instructions
should be
used as a guide to the size of the feedstock
needed to give the best results. Larger sizes than
those suggested will result in prolonging the carbonisation time and could affect the quality of
the product.
The timber should be cut to a maximum length
of 1.5 m. Wood with a diameter greater than
I5 cm should not exceed 1 m in length. Wood
with a diameter greater than 25 cm should be less
than 0.5 m long, and billets more than 30 cm in
diameter should be split.
If possible stack and air-dry freshly felled wood
for at least 6 weeks before use. This will reduce
the burnirlg period and increase the yield.
Loading
the kiln
Lay two lines of ‘stringers’ - medium diameter
(15 cm) lengths of wood laid end to end-along
the floor of the kiln to support the charge and
allow the free flow of gases underneath the wood.
Take care that the bottoms of the 4 metal tubes
are completely free from obstruction.
Using easily ignitable material, lay kindling for a
fire around the base of the pipe opposite the
chimney end of the kiln. This will be lit by dropping hot coals down the inlet pipe after the kiln
has been loaded.
10
Lay small-to I-medium diameter wood across !I78
stringers to form the first layer of the charge.
Load the remainder of the wood making sure that
the larger diameter billets are placed in the centre
of the kiln. Fill rn the sides of the kiln and any
holes between the larger billets with smaller wood
so that the maximum amount of wood is packed
tn.
When the kiln is filled to ground level, place the
metal sheet nearest the chimney end in position
and pack the space underneath with smalldiameter wood.
Next, place the centre sheet in position
the space beneath with wood.
and fiil
Finally, fill with wood the space bsiow where the
third sheet will fit and place the !h;rd sheet in
position. Do not distort the cover by forcing the
sheet down on any protruding billets of wood.
Make sure that the centre sheet is positioned
underneath the edges of the two end sheets with
an overlap of 5 cm.
Support the centra -:?eet by hanging it from a
wooden po!e arranged across the centre of the
kiln with a length of chain.
Secure the 3 metal sheets to each other using
the sliding metal bolts.
Lighting
the kiln
Ooen all the inlet and outlet tubes. Feed hot coals
down the air inlet tube oppostte the chimney end
of the ktln to light the kindling material. The
smoke produced will escape’to the outside
through the short steam-release tube in the mud
wall at the top of the opposite end of the kiln.
During the lighting stage, seal the edges of the
overlapping joints of the metal cover with soil.
Apply soil also to the edges of the metal sheets
overlapping the mud walls at each end of the kiln
and along the sides of the kiln where the cover is
held in place by the angle-iron framework.
In wet conditrons, or when a strong wind is
blowing, place one of the chimney extension
tubes over the end of the steam release tube to
assist the ‘draw’ of smoke out of the kiln.
12
i”‘v .i
After a period of 1 or 2 hours, the end of the kiln
opposite the chimney should be well alight. A
drop of water applied to the cover in that area
will evaporate with a hissing noise. Thick smoke
and steam will leave the kiln through the steamrelease tube at considerable pressure.
When thus stage is reached, assemble the two
extension tubes onto the chimney and seal the
steam-release tube wrth one of the plugs provided.
The smoke will be forced to the bottom of tha
krln and up through the chimney assembly.
Carbonising
wood
the
Carbonisation
is usually completed in about 48
hours. The amount of air entering each of the 3
inlet tubes during this period can be regulated by
partially covering rhe ends of the tubes with the
metal sealing plugs. If there is a strong prevailing
wind, it may be necessary to reduce the amount
of air entering the windward side of the kiln. Any
cracks or joints releasing smoke during the carbonisation period should be sealed with mud or
soil.
The fire in the charge will move steadily from the
lighting end of the kiln towards the chimney.
Seal the air-inlet tube opposite the chimney end
(i.e. the lighting tube) when fire can be seen
through the air-inlet tubes situated half-way along
the kiln’s length. This prevents further air entering
that alea of the kiln where the charcoal has
already been produced.
At the end of the carbonisation
period the smoke
leaving the kiln will be very hot, so that drops of
water applied to the surface of the chimney extension tubes will evaporate with a hissing noise.
The smoke wIIJ also become thin and almost
transparent, with a bluish colour. This indicates
that all the wood In the kiln has been converted
to charcoal.
At this stage, remove the (chimney extension tul 3es
using a pair of heat-proof gloves, and seal t he
kiln completely.
Sealing and cooling
the kiln
Seal all the metal inlet and outlet tubes by inserting the metal plugs and filling the tops of the
tubes with wet mud. Cover all seams and joints
with fine soil to prevent leaks. Check also the
area around the edge of the kiln for leaks and
seal any cracks or holes with mud and fine soil.
When the air supply to the kiln is cut off, the
charcoal will cool rapidly by releasing its heat
through the metal cover of the kiln. The rate of
cooling may be increased by humidifying
the
atmosphere inside the kiln. This is done preferably
on the day after the kiln is first sealed. It is
achieved by pouring about a quarter of a bucketful
of water down each of the air inlet tubes and
quickly resealing ths ! tubes with mu d.
After 3 days, the contents of the kiln should be
cold, providing that it has been sealed properly.
This can be checked by feeling the metal cover
with a bare hand early in the morning before the
heat from the sun exceeds and obscures any heat
remaining in the kiln.
If the kiln has not cooled after 3 days, then
efficient sealing has not been achieved. The kiln
should then be checked once more for leaks and
a further cooling period given.
Before breaking the seal of the kiln, make sure
that the contents are cold and that all tools, sacks
and labour are at hand. Once the kiln is opened,
the charcoal must be removed quickly, as there
is a small chance of fire. Any hot-spots must be
isolated and quenched with water before the fire
spreads.
Unloading
the kiln
To open the kiln clear all mud and soil from the
surface of the metal cover and withdraw the slide
bolts securing the metal sheets. Dismantle the
length of chain and wooden pole used to support
the centre sheet.
Remove the metal sheets at each end of the kiln
first and then the centre sheet. Carry the sheets
well clear of the kiln area to avoid accidental
damage by people walking on them during the
unloading operation.
If fire is seen in the kiln when the cover is
removed, replace the metal sheets immediately
and reseal the kiln for a further cooling period.
After carbonisation,
the contents of the kiln will
have shrunk to about two-thirds of the origrnal
volume. There is usually a fairly deep hole in the
charcoal at the lighting point where the operator
can descend to commence unloading into sacks.
Unload the krln from this point forward towards
the chimney end of the kiln. Use the wooden
support pole located over the centre of the kiln
to suspend a rope and basket to assist the unloading process.
When unloadrng the kiln do not stand directly on
the charcoal as this will break it into small pieces.
Place a piece of flat board over the charcoal
before standing on the product.
When the kiln is nearly empty, a certain a~:, junt
of dust and small pieces of charcoal will h,ive
accumulated on the ktln floor. Recover the larger
pieces of charcoal by shovelling this material out
onto a 10 mm mesh sieve placed on the ground
near the pit. The design of a suitable sieve is
shown in Figure 2.
Finally, before re-loading the kiln with wood,
remove all loose dust and soil from the bottom
of the pit and clear all metal tubes of obstructions.
ing the charcoal
As a precaution against fire, keep freshly-made
charcoal separate from the other stocks for at
least 24 hours. When exposed to atmosphere,
fresh charcoal absorbs oxygen from the air with
an associated rise in temperature. There IS an
associated risk of spontaneous combustion.
Operation
schedule
for two pit kilns
Day
Kiln 1
Kiln 2
1
Remove cover, unload charcoal and tie up
sacks
Clean kiln
Kiln cooling
2
Place stringers and kindling
Load timber and light kiln
Kiln cooling
3
Control charring
Remove cover, unload charcoal and tie up
sacks
Clean kiln
4
Close down kiln
Seal all tubes, joints and cracks with mud and
soil
Place stringers and kindling
Load timber and light kiln
5
Kiln cooling
Humidify by pouring water down inlet tubes
and reseal kiln
Control charring
6
Kiln cooling
Close down kiln
Seal all tubes, joints and cracks with mud
and soil
7
Kiln cooling
Kiln cooling
Humidify by pouring water down inlet tubes
and reseal kiln
Labour input for two kilns
1 Labourer/Chainsaw
1 Kiln operator
1 Kiln assistant
18
operator
Figure 2
Sieve-chute
10 square mesh
-
Icross pole
075 approximately
support pole
length as rewired
_
-----7
I
sack retaining hooks
support poles
0100 approximately
metal band to
hold sack open
c
All dimensions in mm
/
height to enable sack to rest on ground
Copyright
and reproduction
rights
The copyright of publications in this series belongs
to the British Government and is @Crown Copyright 1986
If it is intended to reproduce this guide, or any
part of it, for commercial purposes, such as sale
at a profit or advertising, permissjon must be
obtained in advance from:
The Head
Publications, Publicity and Public Relations
Section
Tropical Development and Research Institute
College House Wrights Lane
London W8 553
Otherwise, the guide, or any part of it, may be
reproduced tin English or in translation) provided
it includes an acknowledgement on the following
lines:
Paddon, A R 11985) The construction, instailation and operation of an improved pit-kiln for
charcoal production. Rural Technology Guide,
Tropical Development
and Research Institute,
No. 15, 20 pp. Price f1.70, including packing
and postage.
No charge is made for single copies of this puhlication sent to governmental and educational
estabiishments, research institutions and nonprofit making organisations working in countries
eligible for British Aid. Free copies cannot normally be addressed to individuals by name but only
under their official titles.
Tropical Development and Research Institute
ISBN 085954 201-7
ISSN 141 898 X
Pnnred m the UK for HMSO
OdEXU962 3,ooO HP Ltd So’ton
20
G3371
7
Figure
DETAIL ON ‘B’
SCALE:- ?4 Full Sia
8 -----1--_.--I
Printedfor H.M.S.0 by C.H & K Ltd, Dd. 830492 2/86 3,000
l-4
G (Stock)
VIEW ON ARROW ‘C’
SCALE:- l/ Full Size
SECTION ON ‘D
..~.-
.-
3660 --
40 x 40 x 5 mild :
angle.
2 and
3 are to be 2440 long.
JO
-0
tween items @
(2120 wide) they “bow”
ape shown. Item @
(which is welded
II stop them springing out. Note items
NOT to be welded to items m
d
When fitted
to the
to item
_-.
...
>
c:
Items m
are to be 130
the tubg are to be made
steel sheet and rolled to
See view on arrow ‘F’ for
(See Note 1)
O/D 3
from
the gi
joint
Item @I
bolted or w
item
10
assembly is
removable
0
J
Earth to fill the gap
between item
10 and
top of the tube (to
ensure an airtight seal)
0
Item @
to be cut so that it will fit inside
the tube (See Note 1)
L
el
l-r
---
:1
DETAIL OF ‘A’
SCALE:- ‘/4 Full Size
,”
-4.14 (Stock)
SECTION ON X - X
----r
Item @I
is to be folded
that a tight fit is obtained
when fitted over items
@ and @ as shown
so
Mark the joints as shown so that
items @ and @
, on reassembly
go back together the same way.
Weld the numbers 1, 2 and 3 on
the sheets as shown.
VIEW ON ARROW ‘F
SCALE:- ‘/s Full Size
.The joint may either be welded
or suitably flanged, bent over and
hammered tight as shown.
ITvoical all ioints - See Note 1)
.
,
m
,-------
always
Om wall - Note -
; Item
x 1 .ofl
the tul
’ made i
I steel s
the gi\
I
I See vie
for joir
(See N
I
/
SECTION ON H - H
\L
Tube
DETAIL ON ‘E’
(TYPICAL ALL TUBES)
SCALE:- X Full Size
drill items @ and @ $12.5.
Item
4 and
315 is to be welded to items
e holes in item
5 may be
larged to suit on final assembly
0
0
DIAGRAM SHOWING A METHOD OF MARKING THE VARIOUS
COMPONENTS,
SO THAT ON REASSEMBLY THEY ALWAYS FIT
BACK TOGETHER THE SAME WAY
SCALE:- 1120 Full Size
Items @ are to be 160
the tubes are to be made
steel sheet and rolled to
See view on arrow ‘F’ for
(See Note 1)
O/D x 1 .Om wall - Note
from mild
the given diameter
joint details
tern @ is to be bolted or welded to
3ne of the chimney tubes as shown
snd made so that the other chimney
:ube can easily slide into it
See Note 1)
to be 130 O/D
mild
and rolled to
iameter
I arrow ‘F
tails Small portions of the earth
are to be cut away to
enable the tubes to be fitted.
When the tubes have been
fitted the earth is to be
replaced as shown
A
L The dimensions
are for guidance
for the hole
only
DETAIL SHOWING THE KILN COVER, INLET TUBES
CHIMNEY AND THE HOLE IN THE GROUND
SCALE:- 1120 Full Size
/
0
f
I.&
DESCRIPTION
DRAWING No.
&
’
z”
Left Hand
Cover
1
Central
Cover
1
tt-
Right Hand
Cover
Long Arm
1
I
7
Air Inlet
Tube
8
Steam Release
Tube
9
Chimney
Connector
2440 x 1220 x l.! 5
Mllc! Steel Sheet
2440 x 1220 x 1.5
Mild Steel Sheet
I I
I I
2
Chimney
REMARKS
3
2440 x 1220 x 1.5
Mild Steel Sheet
40 x 40 x 5 Mild
Steel Angle
Mild Steel Tube,
I 1 .Omm thick wall
I 3CI 1 Mild Steel Tube,
1 .Omm thick
1
I
Mild Steel Tube,
I 1 .Omm thick wall
Mild Steel Tube,
1 .Omm thick wall
Plug I I
4
Bolt
Retainer
13
14
I
8
Handle
Central
2
Support Bracket
15
Locating
16
Clamping
Mild Steel
Sheet
l.Omm
40 x 4 thick
Steel Bar
Slide Bolt
Slide
Pin
Peg
@12 Stock
8
@I2 Stock Steel
4
40 x 4 thick
I Steel Bar
18
Notes
1. Galvanised
AS
or similar.
Galvanised
mild steel
is not to be welded.
Steel
I Bar
I
17
mild steel may be used to make items @[email protected],
but the joints are to be made with
010 and @
Mild
I Bar
I
I
thick
40 x 4 thick Mild
I Steel Bar
@I 2 Stock Steel
Bar
-.
6%
wall
bolts, screws
Mild
/
/
,,’
Y
Position sheets 1 and 3 so that they have a 50mm overlap
18 as shown
with sheet 2. Mark an ‘X’ opposite item
(as long as the sheets are reassembled with the ‘X
18 they will always have the required
opposite items
amount of overlap)
0
0
+--
Weld No.
Weld No.
Weld No.
As shown
always fit
1 on item 4 under sheet No. 1
2 on item 4 under sheet No. 2
3 on item 4 under sheet No. 3
8
(so that the sheets when reassembled
back in their original positions)
Forked branch or similar
to provide a suitable support
for the cross-bar
Cross- bar
--____-.-
z!-
-_I--
..e
I=
i
:.’77
ly--r _
c-_h
.‘...
I
1
I--
mo
-.----~_--_--~*
SECTION ON G - G
Small cut aways are to be
made in the earth at the
tube inlets as shown
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