2inch Class 300 25 Series Pressure Regulator

2inch Class 300 25 Series Pressure Regulator
INSTALLATION AND MAINTENANCE INSTRUCTIONS
IM-3-100-US July 2015
2” Class 300 25-Series Pressure Regulator
Unpack Carefully
Do not lift the regulator by the tubing. Grasp the body of
the valve firmly when lifting. If installed, do not lift the
regulator by the tubing.
Piping
1.Typical hookup sketches as shown in Figs. 1, 2 and 3
will aid in planning a correct installation.
2.Piping on the downstream side of the valve should be
increased so as not to restrict flow. See Steam Velocity
Chart for recommended pipe sizes.
3.Swage nipples are recommended for changes in pipe
sizes.
4.Before installing the valve make sure the piping is free
of foreign material, scale, etc.
5.Make certain the arrow cast on valve body is pointing
in the direction of flow.
6.Valve should always be installed in a horizontal position. (See Figs. 1, 2 and 3.)
7.Press gauges installed on both sides.
Assembling Pilot to Valve Body
1.Remove all protective caps from ports if present.
2. Remove the package of square gaskets from the pilot box and install on the main valve cover assembly (A).
3.
Install pilot on top of gasket just placed on main valve cover assembly (A) so that the sensing line is pointing
in same direction as the valve outlet connection. Be
sure that the guide pin in the cover assembly (A) fits
securely in the guide hole in the pilot. Be sure the pilot
bolts are secured to the valve cover assembly (A) and
tightened.
4.Install a small gate valve in the sensing line so that this
can be closed when servicing the regulator.
5.The sensing line must be pitched downward from themain valve to insure proper drainage.
6.To permit accurate setting of the pressure regulator,
a pressure gauge should be installed as close as possible to the pilot sensing line connection.
Bypass
1.A bypass connection, as shown in Figs. 1, 2 and 3 is
recommended so that the valve can be serviced without shutting down the equipment.
2.The bypass valve should be the same size as the
pressure regulator.
Steam Line Drain Trap
1.To insure proper operation of the valve and avoid
premature wear, it is recommended that a 1/2” Spirax
Sarco thermodynamic steam trap be installed on the
steam supply line. (See Figs. 1, 2 and 3.)
2.A steam trap should also be installed in the downstream piping at the heel of each rise, between all
reducing valves installed in series, and ahead of any
manual or automatic valve. This will prevent condensate accumulation that can result in waterhammer
damage.
Pipeline Strainers
1.It is strongly recommended that strainers be installed
before the reducing valve and steam traps.
2.Make certain adequate clearance is provided for
screen removal and blowdown connection between
strainer and valve body.
Pilot Pressure Sensing Line
Stop Valves
1.Copper or stainless steel tubing (1/4” OD) can be used
for the sensing line with suitable compression fittings or
as alternative 1/4” piping can be used.
All stop valves on the supply side, as well as on the
downstream side of the pressure reducing valve and
sensing line, should be of the gate type so as to insure full
rated capacity and good control.
2.Connect the sensing line to a straight portion of the
piping 10 pipe diameters from the nearest fitting downstream from the valve and approximately 1 foot from
elbows, tees, valves and other restrictions.
(See Figs. 1, 2 and 3.)
3.When the reducing valve is serving a single piece of
equipment, the sensing line can be connected to the
steam space of the equipment.
Separators
1.It is strongly recommended that separators be
installed upstream of regulator complete with trap set.
(For more information, refer to IMI 3.000)
2. See Fig. 3 for proper installation.
Safety
Valve
Steam
Supply
Moisture
Separator
Drip
Pan
Elbow
Strainer
Reduced
Steam
Pressure
Pilot Operated
Pressure Control Valve
Spira-tec
Loss
Detector
Strainer
Check
Valve
Fig. 1
Float &
Thermostatic
Steam Trap
Select inlet piping for reasonable
velocity and expand downstream
for equal flow rate.
Typical Pressure Reducing
Valve Station
Safety
Valve
Pressure
Sensing
Line
Drip
Pan
Elbow
Strainer
Pilot Operated
Pressure Control Valve
Steam
Supply
Pressure
Sensing
Line
Moisture
Separator
Reduced
Steam
Pressure
Strainer
Spira-tec
Loss
Detector
Strainer
Set lead valve 2 psi above desired
set pressure and set lag valve 2
psi below desired set pressure.
Check
Valve
Pilot Operated
Pressure Control Valve
Fig. 2
Float &
Thermostatic
Steam Trap
Parallel Operation of
Pressure Reducing Valves
Pressure
Sensing
Line
Pressure
Sensing
Line
Moisture
Separator
Steam
Supply
Pilot Operated
Pressure Control Valve
Spira-tec
Loss
Detector
Strainer
Note: Intermediate pressure takeoff
requires an additional safety valve.
Drip
Pan
Elbow
Reduced
Pilot Operated
Pressure Control Valve Steam
Pressure
Strainer
Strainer
Safety
Valve
Strainer
Check
Valve
Float &
Spira-tec Thermostatic
Loss
Steam Trap
Detector
Check
Valve
Float &
Thermostatic
Steam Trap
Fig. 3
Series Pressure Reducing Valve
Station for High Turndown Rations
2
Pressure
Adjustment, Spring
or Air
Pressure
Diaphragm
Pressure
Pilot
Orifice
Downstream
Pressure
Sensing Line
Inlet
Main Valve
Control Pressure
Main Diaphragm
How the 25P & 25PA Work
3.Open stop valves in the following order:
Normal positions before start-up are with the main valve
closed and the pilot valve held open by spring force.
Entering steam passes through the pilot valve into the
main diaphragm chamber and also out through the control
orifice. As flow through the pilot exceeds flow through the
orifice, control pressure increases in the diaphragm chamber and opens the main valve. As steam flows through
the main valve, the increase in downstream pressure
feeds back through the pressure sensing line to the underside of the pressure diaphragm. When the force below
that diaphragm balances the compression force of the
spring above it, the pilot valve throttles. The control pressure maintained in the main diaphragm chamber positions
the main valve to deliver just enough steam for the desired
delivery pressure. Adjustment of the spring above the
pressure diaphragm changes the downstream pressure
set point. When steam is no longer required, the sensing
line pressure increases closing the pressure pilot and the
control pressure bleeds back through the control orifice.
This allows the main valve to hold the desired reduced
pressure, and it may close tight for a dead-end shutoff.
a.Open stop valve ahead of steam trap on steam
supply line. This will insure water free steam at the
regulator inlet when put into operation.
b.Open small gate valve on pressure sensing line.
c. Open downstream stop valve.
d. Slowly open inlet stop valve.
4.Slowly adjust pilot spring at (2D) turning clockwise until
reduced pressure required is indicated on pressure
gauge downstream of valves.
5.Once the system has stabilized itself, it may be necessary to make re-adjustment of pilot spring (2D).
Replace spring cover, then tighten adjustment locknut.
6.
Important­––Retighten all pilot flange connections to
insure steam tight joints.
Recommended Torque
2A Screws
13-15 ft. lbs.
2C Screws
15-20 ft. lbs.
Start-up (Refer to Fig. 5)
1.First make certain that all stop valves are closed.
2.Remove pilot spring cover, then turn the pressure pilot
adjustment (2D) counter-clockwise until spring is slack.
Make certain spring remains in vertical position and
centered in its retainers.
7. Air Loading PA Pilot requires air loading as indicated in the following table:
Desired Outlet Steam
Pressure P2 psig
Air Loaded PA Pilots must have no P supplied to them.
Inlet Pressure
P1 psig
Approximate
Air Set Pressure
psig
3
5
10
25
50 75
100
10 psig to 100 psig
11 16 31 56 80 102
to to to to to
to
13.516.833.558 81 103
Troubleshooting
(Refer to Figs. 5)
Symptom
Cause
1. Controlled pressure 1. (a) Dirt or foreign material between pilot
1. (a)
overshoots under valve seat and head.
normal load conditions
Check and Cure
Loosen screw (2d). Remove stainless steel tubing connection at (J). With steam on valve, if steam flows from stainless steel tubing connec-
tion at (J ), remove pilot head and
seat assembly (2H) and clean or replace.
(b) Foreign particles between main valve
head and seat.
(b) Inspect and clean head and seat
(c) Orifices (B) and (H) or pressure sensing
line may be plugged.
(c) Remove, inspect and clean.
2. Controlled pressure 2. (a) Main valve head and seat worn or dirt
2. (a) Inspect and clean head and seat.
overshoots only on between them.
light loads.
(b) Valve may be severely oversized. (b) Adjust screw (2D) to give desired
pressure under light loads.
(c) Bypass valve not shut tightly or leaking.
(d) Dirt or foreign material on main valve
stem and guide (1F).
3. Valve fails to open.
3. (a) Main valve diaphragm ruptured.
(c) Check and repair as required.
(d) Remove, inspect and clean.
3. (a)Unscrew stainless steel tubing connection at
(G) and crack bypass valve. If steam flows
from main valve diaphragm case, diaphragm is
defective and must be replaced.
(b) Orifice (H) is plugged
(b) Remove and clean.
(c) Pilot valve seat is plugged with dirt. (c) Remove head and seat assembly (2H). Inspect and clean or replace.
(d) Screen (1D) is plugged (d) Inspect screen and clean.
(e) Pipeline strainer blocked.
(e) Inspect and clean.
(f) Pilot valve adjustment (2D) not (f)
properly adjusted.
Adjust screw (2D) to desired
pressure.
4. Delivery pressure 4. (a) Pilot valve adjustment (2D) not
4. (a) Adjust screw (2D) to desired pressure.
low.
properly adjusted.
(b) Valve undersized.
(b) Check actual load against valve rating.
(c) Steam supply pressure too low.
(c) Check and correct.
(d) Main valve diaphragm ruptured.
(d)Unscrew stainless steel tubing connection (G)
and crack bypass valve. If steam flows from
diaphragm case, diaphragm is defective and
must be replaced.
(e) Bleed orifice (B) missing.
(e) Replace proper fitting.
5. Valve fails to 5. (a) Bypass valve open or leaking.
5. (a) Check and repair as required.
close.
(b) Pilot sensing line blocked (b) Remove, inspect, clean or install.
(or not installed).
(c) Pilot ruptured (water or steam coming
from pilot at spring retainer area).
(c) Replace pilot diaphragm assembly.
(d) Pilot assembly or main valve seat (d) Check casting in seat area for erosion.
threads leaking.
(e) Main valve diaphragm reassembled (e)
without return spring and main valve
cover holding valve head closed.
4
With main valve cover installed,
loosen all main valve diaphragm
bolts (1C) and then retighten to
recommended torque of 55-60 ft. lbs.
Maintenance
3.To remove head and seat assembly (2H), unscrew
hexagon, using 11/16” hex wrench.
General Inspection (Refer to Fig. 5)
While a program of planned maintenance is always to be
recommended, the Spirax Sarco 25P valve will give long
and trouble-free service if correctly selected, installed and
kept reasonably free of dirt and foreign matter. Dirt and
foreign matter are most likely to collect during installation
and later trouble can be avoided by inspecting the installation after a few days. Check the following:
4.If it is found that either the head or seat is worn, the
entire assembly should be replaced.
Inspecting and Replacing Pilot Valve
Diaphragms (Refer to Fig. 5)
1.Turn adjustment screw (2D) counterclockwise until
spring is slack.
1.Clean all pipeline strainers. (Remove screens to clean.)
2.Remove cap screws (2C). Pilot yoke (2B) can then be
removed.
2.Check the main valve seat (1E) and protective screen
(1D).
3.The 2 metal diaphragms (2F) can then be inspected for
distortion or possible fracture as a result of abnormal
operation.
3. Inspect and clean orifices (B) and (H).
4. Check all joints for leakage.
4.At the same time any accumulation of dirt or foreign
material should be removed from the lower diaphragm
pilot case.
Servicing Procedure (Refer to Fig. 5)
To determine which part of a malfunctioning pressure
reducing valve requires maintenance, refer to the troubleshooting chart and follow this servicing procedure to
check the tightness of the seal.
5.When replacing diaphragms, make certain casting surface is clean to insure a steam tight joint.
1.With all stop valves closed and the valve cooled down,
remove the stainless steel tubing from connector (J),
being careful not to bend it.
6.Position pilot yoke on lower diaphragm pilot casting
making certain that the yoke is properly centered.
7.Tighten all cap screws uniformly to a recommended
assembly torque of 15-20 ft. lbs.
2.Close the pilot valve (2H) by turning the pressure
adjustment (2D) counter-clockwise until the spring is
slack.
Inspecting and Replacing Main Valve Head
and Seat (Refer to Fig. 5)
3.Stand clear of the tubing connectors and open the inlet
stop valve slightly so that a small amount of steam
reaches the valve inlet and pilot.
1. Unscrew stainless steel tubing connections at (J).
2. Remove main valve cover cap screws (1A).
4.Open and close the pilot valve a few times by turning
the pressure adjustment (2D) and observe the steam
flow from tubing connector (J). When the pilot valve is
closed, there should be no steam flow from the connectors; if there is some steam flow, it indicates that
the pilot valve assembly (2H) is faulty and must be
replaced.
3.Remove main valve cover, strainer screen (1D), spring
support disc and head spring.
4.Head (1B) can then be removed by simply withdrawing
with a pliers or similar tool.
5.Inspection should then be made to determine if scale
or other foreign material prevented tight closure of the
head and seat.
5.With both pieces of stainless steel tubing removed, the
main valve head and seat are held closed and should
not pass any steam. Observe the downstream orifice
connector (B). Steam flow from this connector indicates that the main valve head and seat are leaking
and require servicing.
6.If the head or seat shows signs of wear, this can be
corrected by grinding, using a fine grinding compound
(400 grit) providing the wear is not too severe. Check
for body erosion.
Inspecting and Replacing Pilot Valve Head
and Seat (Refer to Fig. 5)
7.If it is necessary to replace the valve seat, this can be
removed from the valve body using a standard hexagon socket. When replacing the valve seat, a new gasket should be used to insure a tight joint.
1.Remove 4 (2A) pressure pilot flange cap screws and lift
off pressure pilot. Visual examination can be made of
the pilot valve head and seat.
2.Pilot valve head and seat are contained in one complete assembly.
5
Inspecting and Replacing Main Valve
Diaphragms (Refer to Figs. 5)
1.Unscrew stainless steel tubing connection at (G).
2. Remove main valve diaphragm bolts (1C).
3. This will allow the lower diaphragm case to be removed.
4.The 2 metal diaphragms (1H) should be inspected to
insure that they have not become distorted or possibly
fractured as a result of abnormal operating conditions.
5.At the same time any accumulation of dirt or foreign
material should be removed from the diaphragm case.
6.The valve stem should also be checked to make sure
it is free to move and that there is no scale or foreign
material lodged in the guide bushing (1F).
7.Before reassembling diaphragms, main valve head
must be in place and head in a closed position with
the return spring and main valve cover.
8.Make certain pressure plate (1G) is set properly.
(Refer to Fig. 4.)
9.Care should be taken in centering the diaphragms
properly and equalizing bolt take-up uniformly.
Recommended screw assembly torque is 55-60 ft.
lbs.
Head on Seat
Adjustment
& Locknut
A
Pressure Plate
1G
Figure 4 - Top of valve must be completely assembled
and head must be on seat when adjusting pressure plate
and when re-assembling diaphragms to insure “A” = 1/8”
for 2” valve.
6
J
J
B
G
G
Figure 5
1D
2A
1A
1A
2D
1B
1D
2D
2B
1E
2F
2C
1G
1F
1C
2A
1H
G
H
Figure 6 - 2” Class 300, 25 Valve Components
7
2H
How to Size Piping for
25-Series Regulators
Principle
When steam pressure is lowered through a reducing valve, the steam expands creating a higher
velocity. The extreme velocities that must exist
across reducing valve seats cannot be tolerated in
pipes supplying the valves and leading from them.
Erosion and noise would be prohibitive.
It is recommended practice in heating systems to
limit velocities to between 4,000 and 6,000 feet
per minute. Higher velocities are often acceptable
outdoors and in plants where the environment is
already noisy.
This chart lists steam capacities of pipes under
various pressure and velocity conditions.
Example
Given a steam heating system with a 100 psig inlet
pressure ahead of the pressure reducing valve and
a capacity of 1,000 pounds per hour at a reduced
pressure of 25 psig, find the smallest sizes of
upstream and downstream piping for reasonable
steam velocities.
Upstream Piping
Enter the velocity chart at point A for 1,000 pounds
per hour. Proceed horizontally to point B where the
100 psig diagonal line intersects.
Follow up vertically to point C where an intersection
with a diagonal line falls inside the 4,000 to 6,000
feet per minute velocity band. Actual velocity (see
point D) is about 4,800 feet per minute for 1-1/2
inch upstream piping.
Downstream Piping
Enter the velocity chart at point A for 1,000 pounds
per hour. Proceed horizontally to point E where the
25 psig diagonal line intersects.
Follow up vertically to point F where an intersection
with a diagonal line falls inside the 4,000 to 6,000
feet per minute velocity band. Actual velocity (see
point G) is about 5,500 feet per minute for 2-1/2
inch downstream piping.
Spirax Sarco Applications Engineering Department
Toll Free at:
1-800-833-3246
SPIRAX SARCO, INC. • 1150 NORTHPOINT BLVD. • BLYTHEWOOD, SC 29016
PHONE 803-714-2000 • FAX 803-714-2200
8
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