Bulletin No. AY-736-B Model GD-6, GD-6N Pressure Reducing Valve Installation and Maintenance Instructions Installation for Steam Service - Model GD-6N Globe Valve Minimum of 10 Outlet Pipe Diameters from Last Valve or Fitting By-Pass Safety Relief Valve Armstrong Strainer GD-6N Minimum of 20 Outlet Pipe Diameters from PRV to First Turn Minimum of 10 Inlet 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. Armstrong TVS Trap Installation for Liquid/Gas Service - Model GD-6 Globe Valve Minimum of 10 Outlet Pipe Diameters from Last Valve or Fitting By-Pass Safety Relief Valve Armstrong Strainer GD-6 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 10 psi higher or 10% higher than the downstream pressure, whichever is greater. Note: For liquid application, liquid drainer not required Armstrong Liquid Drainer Trap This bulletin should be used by experienced personnel as a guide to the installation of the Models GD-6 and GD-6N Pressure Reducing Valves. 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 information. Installation Instructions 1. An Armstrong Inverted Bucket Steam Trap is recommended to drain condensate at the inlet of the Pressure Reducing Valve (PRV). A Liquid Drainer is recommended for gas service. 4. If system cannot be turned off to service PRV then piping a by-pass line with a high quality globe valve around the PRV will allow manual system operation while the PRV is being serviced. 2. An Armstrong Y-Strainer (20-100 mesh, depending on system dirt) should be installed before the PRV to reduce the chance of dirt fouling. 5. Do not install quick opening or closing valves downstream of the PRV. 3. Pressure gauges should be installed before and after the PRV. 6. Install the PRV with the flow in the direction of the arrow on the body. Start-Up and Adjustment Procedures Improper adjustment of the pressure reducing valve may cause hunting, scale problems, water hammer, etc., and damage to the valve itself. Damaged pressure gauges, leakage or opening of a bypass valve, or clogging of an inlet strainer may cause problems similar to that of a malfunctioning reducing valve. Adjust the valve as follows: 4. Slowly turn the adjusting screw clockwise until the desired pressure is obtained on the downstream pressure gauge. 1. Close the gate valves before and after the pressure reducing valve. Open the globe valve slowly in the bypass line and blow down the inlet piping. Adjust the opening of the bypass valve so the safety valve, if installed, does not blow. After blowing the system down, close the bypass valve. 5. Slowly open the outlet valve to the fully open position. 6. Adjust pressure again after system stabilizes and when there is a load on the system. Turning the adjusting screw: - Clockwise increases pressure, counter-clockwise decreases pressure. 2. Loosen the lock nut and adjusting screw to relieve the adjusting spring. 3. Slowly open the inlet side gate valve to the fully open position, and partially open the outlet valve so only a small amount of steam, liquid or gas can pass. 7. Tighten the adjusting screw lock nut after adjustment is completed. Troubleshooting Guide Problem The desired pressure cannot be obtained. The outlet pressure rises higher than the specified pressure Abnormal noise is heard. Causes The inlet pressure is too low or high. The sensing port of the outlet pressure is clogged with foreign matter. The valve size is smaller than what is required. The adjustment is not appropriate. The inlet strainer is clogged by foreign substance. The pressure gauge is not properly functioning. The valve or the valve seat are contaminated by foreign substance. The by-pass valve is leaking. Excessive air is in the system. The reducing ratio is greater than 10:1. Water hammer (for steam service) Air trouble (for liquid service) There is a fast closing valve near the PRV. 2 Solutions Adjust the pressure to the appropriate level. Disassemble and clean the sensing port. Change the valve size to the appropriate one. Readjust according to the adjustment procedure. (See start-up procedure) Disassemble and clean the strainer. Replace the pressure gauge. Disassemble and clean the valve or the seat. Repair or replace the by-pass valve. Install an air vent. Reduce pressure by staging with second PRV. Install a drip trap before the PRV. Install an air vent. Provide as much distance as possible between the two valves. GD-6N (Steam) Disassembly Reassembly Main Valve 1. Check to be sure that the valve and seat are not damaged. 1. Turn the bottom cap (2) counter-clockwise for removal. Then remove the valve (7) and the spring (16) from the body (1). 2. Reassemble in reverse order. Note: Replace all gaskets where disassembly is required. Diaphragm 1. Remove the cap (not shown) and loosen the lock nut(14). Turn the adjusting screw (13) counter-clock wise to unload spring tension. 2. Remove the spring housing bolts (20) and the spring housing (3). Remove the top spring plate (6), the adjusting spring (15) and the diaphragm (17). Adjusting Screw (13) Bolt (20) Lock Nut (14) Rivet (27) Gasket (23) Nameplate Spring Housing (3) Spindle (9) Top Spring Plate (6) Main Valve Seat (8) Adjusting Spring (15) Guide Pipe (25) Body (1) Nut (19) Lock Washer (18) Valve Seat (8) Bottom Spring Plate (5) Valve (7) Diaphragm (17) Spring (16) Gasket (24) Screen (10) Nut (12) Gasket (21) Cap (2) 3 Disassembly GD-6 (Liquid/Gas Service) Reassembly Main Valve 1. Turn the bottom cap (2) counter-clockwise for removal. Then remove the valve (7) and the spring (18) from the body (1). Diaphragm 1. Remove the cap (not shown) and loosen the lock nut (16). Turn the adjusting screw (15) counterclockwise to unload spring tension. 1. Check to be sure that the valve and seat are not damaged. 2. Reassemble in reverse order. Note: Replace all gaskets where disassembly is required. 2. Remove the spring housing bolts (22) and the spring housing (3). Remove the top plate (6), the adjusting spring (17) and the diaphragm (19). Bolt (22) Adjusting Screw (15) Locknut (16) O-Ring (27) Spring Housing (3) Guide (13) Nameplate Guide Pipe (26) Body (1) Rivet (29) Top Spring Plate (6) Valve Seat (12) Spindle (8) Disc (9) Adjusting Spring (17) Nut (21) Spring Washer (20) Bottom Spring Plate (5) Valve (7) Flat Washer (10) Nut (11) Diaphragm (19) Gasket (25) Spring (18) Gasket (23) Bottom Cap (2) Diaphragm Stopper (14) Gasket (24) Armstrong International, Inc. 816 Maple Street, Three Rivers, Michigan 49093 - USA Ph: (269) 279-3600 Fax: (616) 273-8656 Bulletin No. AY-736-B 5/01 armstronginternational.com Printed in U.S.A.
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