Bulletin No. AY-745-A Model GD-45 Pressure Reducing Valve Installation and Maintenance Instructions This bulletin should be used by experienced personnel as a guide to the installation of the Model GD-45 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 information. Installation for Air Service Installation Instructions Globe Valve Minimum of 10 Outlet Pipe Diameters from Last Valve or Fitting By-Pass Safety Relief Valve Armstrong Strainer 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. GD-45 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. Armstrong Liquid Drainer Trap 3. Pressure gauges should be installed before and after the PRV. 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. Installation for Steam Service Globe Valve 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 air service. Minimum of 10 Outlet Pipe Diameters from Last Valve or Fitting By-Pass Safety Relief Valve GD-45 6. Install the PRV with the flow in the direction of the arrow on the body. Armstrong Strainer Minimum of 10 Inlet Pipe Diameters from PRV to First Turn Armstrong TVS Trap 5. Do not install quick opening or closing valves downstream of the PRV. 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. 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: 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 does not blow. After blowing the system down, close the bypass valve. 2. 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 or air can pass. 3. To increase the downstream pressure, turn the adjusting screw clockwise until the desired pressure is obtained on the downstream pressure gauge. 4. Slowly open the outlet valve to the fully open position. 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 functioning properly. The valve or valve seat is contaminated by foreign substance. The by-pass valve is leaking. The reducing ratio is excessively large. Water hammer (for steam service). There is a fast closing valve near the PRV. Solutions Change 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. Reduce pressure by staging with second PRV. Install a steam trap at the reducing valve inlet. Provide as long a distance as possible between the two valves. Disassembly (11) Adjusting Screw 1. Eliminate pressure from inside the valve. Make sure the valve is completely free from pressure. 2. Turn the adjusting screw (11) counterclockwise to make the spring (12) free (not loaded). 3. Remove the bolts (15) and take away the spring housing (2) (the handle cannot be disassembled). Take out the spring (12), bellows (10) and valve rod (8). 4. Unscrew (counterclockwise) the cap (3) and take out the spring (13), screen (9) and valve (7) from the body (1). (23) Nameplate (15) Bolt Body (1) Valve Seat (6) Valve (7) (2) Spring Housing Main Valve Spring (13) (26) Spring Retainer Screen (9) (12) Adjusting Spring Gasket (16) Cap (3) (10) Bellows Reassembly E-Ring (20) (17) Gasket 1. Check all parts to make sure they are in good condition before putting back together. (8) Valve Rod 2. Lap valve (7) and valve seat (6) with 1000 grit lapping compound if needed to ensure no leakage. 3. Reassemble in reverse order as disassembly. Note: Replace all gaskets where disassembly is required. Armstrong Pressure/Temperature Controls Group, 221 Armstrong Blvd., Michigan 49093 - USA Ph: (269) 279-3600 Fax: (269) 273-8656 Bulletin AY-745-A 8/03 www.armstrong-intl.com Printed in U.S.A.
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