Bulletin No. AY-720-B
Model GD-2000K
Pressure Reducing Valve
Installation and Maintenance Instructions
Typical Single Stage Reduction
For Steam
Air In
Air Loading
Control Panel
Minimum of 10 Outlet
Pipe Diameters from
Last Valve or Fitting
Safety Relief
Minimum of 10 Inlet
Pipe Diameters from
PRV to First Turn
Minimum of 20 Outlet
Pipe Diameters from
PRV to First Turn
Note: Safety Relief Valve to be set at
10 psi higher or 10% higher than the
downstream pressure, whichever is greater.
TVS Trap
This bulletin should be used by experienced personnel as a guide to the installation of the Model GD-2000K Pressure
Reducing Valve. Selection or installation of equipment should always be accompanied by competent technical
assistance. You are encouraged to contact Armstrong International, Inc. or its local representative for additional
Installation Instructions
1. An Armstrong Inverted Bucket Steam Trap is
recommended to drain condensate at inlet of PRV.
5. If two stage reduction is needed, a minimum of 20 pipe
diameters between valves is recommended.
2. An Armstrong Y-strainer should be installed before the
PRV to reduce the chance of dirt fouling.
6. By-pass line around PRV will allow system operation
while valve is being serviced.
3. Pressure gauges should be installed before and after
the PRV. The downstream gauge should be installed
in or near the control pipe (5/16” O.D.).
7. Install PRV with main diaphragm housing up and
making sure the flow is in the direction of the arrow on
the PRV body.
4. Control pipe connects into a 1/4” tapping on the side of
the main valve. Be certain the control pipe is pitched
away from the PRV. Erratic control could result if this
is not done. Pipe length should be a minimum of 10
outlet pipe diameters.
8. Do not install quick opening and closing valve on the
downstream side of PRV.
GD-2000K Startup and Adjustment Procedures
Improper adjustment of the pressure reducing valve may cause hunting, improper control and possible damage to the
valve itself. Adjust the valve as follows:
1. Check to make sure all stop valves are closed.
4. Set the operating air pressure to “no-pressure”.
2. Open the stop valve for the trap installed before the
pressure reducing valve.
5. Open the sensing pipe gate valve.
3. Open the stop valve and adjust the valve travel of the
by-pass line globe valve. Blowdown the fluid to remove
foreign matter. After blowing it down, close the bypass line globe valve.
6. Open the stop valve at the outlet side of the pressure
reducing valve. Adjust the position of the stop valve so
that a little fluid flows.
7. Confirm that the condensate is discharged from the
inside of the pressure reducing valve, and slowly open
the stop valve on the inlet side.
8. Be sure to allow some bleed-off the operating air
pressure to the needle valve. (For standard unit needle
valves, the valve opening should be turned 1/2 to 1
10. After the system stabilizes, make any necessary
11. When the adjustment is completed, secure the handle
of the standard control unit’s pressure reducing valve.
12. Check for leakage. Retighten if necessary.
9. While watching the outlet pressure gauge, increase
the operating air pressure (at standard control unit,
etc.), until the desired pressure is reached.
Troubleshooting Guide
Pressure does not Incorrect pressure is being used.
reach the desired
Main diaphragm (11) is damaged.
Sensing pipe is clogged.
Nominal size is too small for the specifications.
Pressure is not adjusted correctly.
Outlet pressure
raises above the
specified value.
Strainer installed before pressure reducing valve
is clogged.
Pressure gauge is faulty.
Check for foreign matter stuck to main valve (5)
and main valve seat (6), or for scratches on
Reduced pressure is not adjusted correctly.
Foreign matter is stuck to clearance between
main spindle (8) and guide (9).
Trap is not provided for dead end pipe.
Fluid leaks from by-pass valve.
Valve operation is Flow at the connection of the sensing pipe
fluctuates excessively.
not stable.
Condensate remains in the sensing pipe.
Sliding movement of main spindle (8) and
guide (9) is sticking.
The operating air pressure is too high or
Correct the pressure. (Note that the reduced
pressure must be 90% or below the inlet
pressure (gauge pressure).
Remove plug (24-1) and open the by-pass valve.
If the fluid runs out from plug, replace the main
Disassemble and clean.
Change the nominal size appropriately.
Observe the adjustment steps and readjust
Disassemble and clean.
Set the operating air pressure to "no-pressure".
If fluid runs out from tee when it is supplied from
inlet side of the pressure reducing valve, clean
the main valve and main valve seat. When any
scratches are identified, lap the main valve and
main valve seat.
Observe the adjustment steps and readjust
Remove them for inspection and cleaning.
Install a trap.
Repair or replace.
Examine the connecting pipe and change it if
scale build-up is present.
Connect the sensing pipe in upward slope to
pressure reducing valve.
Disassemble and clean the valve, or replace the
parts for proper movement.
Observe the adjustment steps and readjust
pressure. Check gauges for proper function.
Main Valve
1. Remove bolts from cover (4). Remove the cover from
the body (1) and remove main valve spring (12) and
main valve (5).
2. Special tools are required when removing main valve
seat (6) due to dimensions unique to ArmstrongYoshitake.
Main Diaphragm
1. Remove bolt (18) of bottom diaphragm case (3).
Remove the bottom diaphragm case, main
diaphragm (11) and retainer (10).
1. Check that there is no damage on the main valve,
main valve seat, pilot valve, and pilot valve seat. Any
damage on the sealing surface may cause leakage.
2. Move the sliding section (pilot valve, main spindle,
etc.) two or three times and confirm they are moving
smoothly. If they do not move smoothly, original
performance may be affected. Re-lap and cleaning
must be performed. (See Bulletin AY-768).
3. After the main valve, spring and spring plate are
assembled correctly, mount the main diaphragm.
Incorrect assembly may affect the original performance.
4. Replace gaskets with new ones when disassembling.
Using old gaskets may cause steam leakage,
resulting in burns.
5. Tighten the nuts evenly. Tightening insufficiently may
cause steam leakage, resulting in burns.
6. Assemble in the reverse order of disassembly.
Note: Apply a fluid sealant (heat and steam resistant) to
the bottom sealing surface of the top and bottom sealing
surface of the main diaphragm.
Plug (24)-1
Rivet (20)
Nut (17)
Bolt (18)
Nameplate (19)
Stud Bolt (16)
Bottom Diaphragm
Case (3)
Gasket (13) or (23)
Body (1)
Main Diaphragm (11)
Gasket (7)
Plug (14)
Plug (24)-2
Main Valve
Seat (6)
Retainer (10)
Main Spindle (8)
Main Valve (5)
E-Ring (28)
Main Valve
Spring (12)
Joint (30)
Gasket (13)
Cover (4)
Top Diaphragm
Case (2)
Bolt (15)
Guide (9)
The above structure differs depending on size.
Air Loading vs. Steam Outlet
Additional Air Required
Differential Steam Pressure ! P
Use this chart to determine the air loading pressure you need to control a specific steam
outlet pressure.
Air Loading vs. Steam Outlet
(Selection Example)
Example: Using 1-1/2” GD-2000K
Steam initial pressure P1 = 200 psig
Steam outlet pressure P2 = 75 psig
Differential pressure !P = 125 psig
Read horizontally across the bottom of the chart to the 125 psig !P
line. Then read vertically up to the diagonal line that corresponds to a
1-1/2” GD-11K. Then read horizontally to the left for additional air signal
Outlet pressure P2 = 75 psig
Additional air !P air = 12 psig
Total air pressure required = 87 psig
Armstrong-Yoshitake, Inc.
Bulletin No. AY-720-B 3/01
221 Armstrong Blvd., P.O. Box 408, Three Rivers, Michigan 49093 - USA Ph: (616) 279-3600 Fax: (616) 273-8656
Steam Traps \ Humidifiers \ Steam Coils \ Valves \ Air Vents \ Pumping Traps \ Water Heaters
Printed in U.S.A.
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