Discontinued. Powers Controls. Technical Instructions Document No P25 RV Rev. 1, May, RV 201 Pressure Reducing Valves.

Transcription

1 Powers Controls RV 201 Pressure Reducing Valves Description Features Product Numbers Dual Pressure PRV Technical Instructions Document No P25 RV Single Pressure PRV The RV 201 Pressure Reducing Valve (PRV) is a diaphragm operated self-relieving regulator valve that provides precision control of air supply pressures for pneumatic control systems. A single compact assembly provides a single or dual pressure regulating valve, a safety relief, and a pilot port for gauge indication. The PRV can mount in any position and is adaptable to wall mounting (bracket provided) or a pipe supported installation. The dual pressure PRV is piloted to regulate the reduced pressure at either of two selected control pressure values. Integral safety relief valve 2-1/2 inch (64 mm) gauge with 0 to 30 psig (0 to 207 kpa) 200 mesh stainless strainer Locking handle Single-stage, compressed air pressure reducing valve Dual-stage, compressed air pressure reducing valve

2 Technical Instructions Powers Controls RV 201 Pressure Reducing Valves Application The primary function of the RV 201 PRV is to regulate the control air pressure for a pneumatic control system. Although the primary supply pressure may vary from 60 to 125 psig (413 to 861 kpa) depending on the compressor size and operating differentials, the reduced pressure must be precisely regulated to maintain consistent control operation and calibration. The single air pressure regulator is appropriate for any pneumatic system requiring a consistent regulated source of control air for system components. Single pressure regulators are normally adjusted to maintain the controlled air pressure at the highest acceptable value to ensure the highest possible system capacity, and to compensate for any line losses in the control air piping (Figure 1). CLEAN DRY AIR 150 PSI (1033 kpa) MAX VP0136R1 IN REGULATED OUT AIR SUPPLY ADJUSTABLE UP TO A MAX. OF 35 PSI (240 kpa) RV 201 SINGLE PRESSURE REGULATOR Figure 1. Single Air Pressure Regulator Application. The dual air pressure regulator provides either of two selected control air pressures. This step changes to a different control air pressure implements mode or system changes to pneumatic instruments and other mechanical system components in any number of locations. The regulator maintains a source of control air supply for all instruments at either of the selected control pressures. Individual dual pressure systems can be applied to separate zones or areas to achieve a greater degree of centralized control (Figure 2). Figure 3 shows a typical dual pressure system with recommended pressure settings. NOTE: AIR PRESSURE APPLIED TO TOP MUST BE WITHIN 2 PSI (13.78 kpa) OF REGULATOR OUTLET CLEAN DRY AIR 150 PSI (1033 kpa) MAX VP0137R1 IN OUT RV 201 DUAL PRESSURE REGULATOR TWO POSITIION PNEUMATIC SWITCH ACTUATED MANUALLY, ELECTRICALLY, OR PNEUMATICALLY REGULATED AIR SUPPLY AIR APPLIED NO AIR APPLIED TO TOP TO TOP HIGHER OF LOWER OF TWO SETTINGS TWO SETTINGS Figure 2. Dual Air Pressure Regulator Application. 25 PSIG (172 kpa) 23 PSIG 24 PSIG (159 kpa) (165 kpa) AIR PRESSURE ADJACENT TO AIR COMPRESSOR OR REGULATOR NOMINAL SPAN FOR INTEGRAL CHANGE OVER MECHANISM 21 PSIG (145 kpa) 18 PSIG (124 kpa) PD = 1 PSI (6.9 kpa) 23 PSIG (159 kpa) 21 PSIG (145 kpa) 17 PSIG (117 kpa) AIR PRESSURE AT FARTHEST POINT IN DISTRIBUTION PIPING RECOMMENDED PRESSURES IN PSI (kpa) SYSTEM PRESSURE DROP TO LOW HIGH FARTHEST POINT 18 (124) 25 (172) 18 (124) 26 (179) 18 (124) 27 (186) 1 (6.9) 2 (14) 3 (21) Figure 3. Typical Dual Pressure System Pressure Settings. Page 2

3 Powers Controls RV 201 Pressure Reducing Valves Technical Instructions Specifications Operating Maximum inlet pressure 150 psig (1033 kpa) Outlet pressure range: Single pressure PRV 2 to 35 psig (14 to 240 kpa) Dual pressure PRV Higher pressure 35 psig (240 kpa) maximum Lower pressure 2 psig (14 kpa) minimum Differential 0 to 14 psig (0 to 96.5 kpa) Integral relief valve: Adjustment span 20 to 40 psig (137 to 275 kpa) Factory setting 30 psig (206 kpa) Air capacity 10 scfm (4720 cm 3 /S Ambient temperature range 40 to 140 F (4.4 to 60 C) Stability with 25 psig (172 kpa) change in supply Within 0.4 psig (2.76 kpa) Repeatability Within 0.6 psig (4.13 kpa) Physical Piping connections: Inlet and outlet 1/4-inch NPT Outlet gauge 1/8-inch NPT Pilot chamber (dual pressure PRV) 1/8-inch NPT Filter Integral 200 mesh screen filter Body Zinc die cast Finish Iridescent chromate Bracket for wall mounting Standard all units Outlet pressure gauge 2-1/2 inch (64 mm) diameter 0 to 30 psi (0 to 207 kpa) Adjustments Primary pressure 1/8-inch Allen wrench Higher pressure (dual pressure PRV) Adjustable nut Dimensions See Figures 14 and 15 Page 3

4 Technical Instructions Powers Controls RV 201 Pressure Reducing Valves Operation Sizing Pressure regulation is achieved by allowing the actual regulator pressure to counterbalance the desired pressure setting (spring force). A balanced condition exists when the two forces are equal. Too high an air pressure unbalances the main diaphragm assembly toward exhausting or lowering the air pressure. Too low an air pressure unbalances the diaphragm assembly downward toward opening the supply valve to admit enough supply air to raise the regulated air pressure. The design of the RV 201 PRV includes a large diaphragm/supply valve ratio to allow consistent regulation over a wide flow range. Dual pressure regulators include a piston assembly in the upper housing so that a positive pneumatic pilot signal increases the regulator spring tension (previously adjusted for lower pressure setting). This forces the regulator to operate at a higher output pressure. The pilot operated piston assembly in the upper housing is adjusted for a fixed travel to ensure consistent repeatability of the higher pressure setting. SUPPLY VALVE PLUNGER ASSEMBLY VP0129R1 SPRING HIGH PRESSURE INLET SCREEN FILTER ADJUSTMENT SCREW LOCKNUT Figure 4. RV 201 PRV Operation. UPPER HOUSING MOUNTING BRACKET RELIEF VALVE & DIAPHRAGM ASSEMBLY REGULATED OUPUT RELIEF VALVE ASSEMBLY Both single and dual pressure PRVs maintain and deliver an acceptable control air pressure over wide flow variation. The maximum capacity requirement for a PRV can be defined as the maximum instantaneous demand that can occur. This maximum demand is higher than the average flow requirements. RV 201 PRV valves are rated for a nominal 10 scfm (4720 cm 3 /S) capacity. As system flow requirements increase, a slight droop or deterioration of control pressure can occur (Figure 5). In a single pressure system, this control pressure droop has little or no effect on the operation of controls in the system. However, dual pressure systems require a very stable control air pressure for proper operation. Particular care should be taken when selecting PRVs for dual pressure systems to ensure adequate capacity without excessive droop. Page 4

5 Powers Controls RV 201 Pressure Reducing Valves Technical Instructions REGULATED PRESSURE kpa PSI Installation Adjustment Procedure VP0135R PILOT GAUGE PRESSURE ACTUAL DELIVERED PRESSURE CFM FLOW Figure 5. Chart of Typical Flow Requirements. Refer to Figure 3 for typical dual pressure setting. Pressure regulating valves can be used in multiples to accommodate total compressor capacity, if each PRV is the sole source for a zone or area. Using two PRVs in parallel at the same pressure setting is not recommended. If this is attempted and the two PRVs are not operating at exactly identical pressures, the PRV with the lower setting may bleed constantly. Regulated Pressure The single pressure PRV is easily reset to any desired pressure from 2 to 35 psig (13.78 to 35 kpa) with the Allen screw adjustment provided (Figure 6). The same adjustment is used to set the lower pressure for dual pressure PRVs with no air in the pilot chamber (Figure 7). To reset the higher pressure for dual pressure PRVs, apply full control pressure to the pilot chamber and turn the adjustment nut until the correct setting is reached (Figure 8). CAUTION: For dual pressure PRVs, be certain to adjust the lower pressure before setting the higher pressure. Any regulated setting of 30 psig (206.7 kpa) or higher will require resetting the integral relief valve to a higher value. Figure 6. Setting the Single PRV Pressure. Figure 7. Setting the Dual PRV Lower Pressure. Figure 8. Setting the Dual PRV Higher Pressure. Page 5

6 Technical Instructions Adjustment Procedure (Continued) Relief Valve Change the relief valve setting as follows: Powers Controls RV 201 Pressure Reducing Valves Preventive Maintenance 1. Loosen the locknut. 2. Set the regulator for the desired pressure that should actuate the relief valve. If necessary, tighten the relief valve adjustment screw (clockwise) to prevent the relieving of air pressure. 3. Slowly turn the relief valve adjustment screw counterclockwise until the relief valve opens (Figure 9). 4. Lower the regulator pressure setting until the relief valve closes. 5. To verify calibration, re-adjust the regulator pressure upward until the relief valve opens. Optimize regulator operation and life as follows: Figure 9. Changing the Relief Valve Setting. 1. Install an adequate filter on the inlet side of the regulator to prevent particulate matter from accumulating in the supply and exhaust valve mechanisms. 2. The air supply should be dry and essentially free of excessive water and oil that could condense within the regulator. 3. A dust cap is provided on dual pressure PRVs to protect the primary Allen wrench adjustment screw from accumulated dirt and grime. This cap should remain on the regulator except when actually adjusting the pressure setting. 4. For dual pressure PRVs, the upper housing and piston seals should be periodically cleaned and lubricated to provide an air seal and to prevent unnecessary wear. Page 6

7 Powers Controls RV 201 Pressure Reducing Valves Technical Instructions Corrective Maintenance Replacement of Piston Seals Replacement of Relief Valve and Diaphragm Assembly The following parts are required to replace the piston seals on the dual pressure PRV: O-ring Cup Packing Replace the piston seals (Figure 10) as follows: 1. Remove the upper housing by removing the four hex head cap screws. 2. Remove the piston assembly from the upper housing. 3. Install new O-ring and cup packing in piston assembly. NOTE: Lubricate the interior surface of the upper housing with silicone grease before replacing the piston assembly. The following part is required to replace the relief valve and diaphragm assembly: Relief Valve Replace the relief valve and diaphragm assembly (Figure 11) as follows: 1. Remove the upper housing to gain access to the relief valve and diaphragm assembly. 2. Replace the relief valve and diaphragm assembly. Figure 10. Replacing the Piston Seals. 3. Reassemble the unit. Figure 11. Replacing the Relief Valve. Page 7

8 Technical Instructions Powers Controls RV 201 Pressure Reducing Valves Renew Valve Plunger Renew the valve plunger (Figure 13) as follows: Renew Valve Assembly 1. Remove the upper housing and diaphragm assembly to gain access to the valve plunger unit. 2. Remove the diaphragm spring and the plunger assembly. 3. Replace the O-ring on plunger assembly and diaphragm spring. NOTE: Lubricate the internal surface of valve plunger housing with silicone grease before replacing the unit. 4. Reassemble the unit. NOTE: Install the valve plunger spring with the large diameter upward toward the diaphragm and relief valve assembly. The following parts are required to renew the valve assembly: O-ring Spring Renew the valve plunger (Figure 13) as follows: 1. Remove the locknut and relief valve adjustment screw by turning it counterclockwise. 2. Remove the spring and valve disc assembly. 3. Inspect and clean the seating surface if necessary. 4. Replace the O-ring on the disc assembly and install the new spring. 5. Reassemble the unit. Figure 12. Renewing the Valve Plunger. Figure 13. Renewing the Valve Assembly. Page 8

9 Powers Controls RV 201 Pressure Reducing Valves Dimensions 2-1/2" (63.5) Technical Instructions 3-5/16" (84) 6-7/16" (163.5) VP0133R1 3-7/8" (98) 1-19/32" (40.5) 5-1/32" (128) 3-13/32" (137) 3" (76) 2-1/2" (63.5) Figure 14. Single Pressure PRV Dimensions in Inches (Millimeters). 6-23/32" (171) VP0134R1 4-1/32" (102) 1-19/32" (40.5) 2-1/2" (63.5) 5-13/32" (137) 5-13/32" (137) 3-5/16" (84) 3" (76) 2-1/2" (63.5) Figure 15. Dual Pressure PRV Dimensions in Inches (Millimeters). Page 9

10 Technical Instructions Construction Powers Controls RV 201 Pressure Reducing Valves 6 VP0130R1 5 Figure 16. Single Pressure PRV VP0131R1 Figure 17. Dual Pressure PRV Table 1. Single Pressure PRV. Item Part No. Part Name No. Required. Material Spring 1 Steel /4 x 3/8 x 1/16 O-Ring 1 Rubber Valve Disc & Pin Assembly Spring 1 Steel /2 x 5/8 x 1/16 O-Ring 1 Rubber Mounting Bracket 1 Steel Table 2. Dual Pressure PRV. Item Part No. Part Name No. Required Material /2 x 5/8 x 1/16 O-Ring 1 Rubber Clip Packing 1 Rubber /4 x 3/8 x 1/16 O-Ring 1 Rubber Spring 1 Steel Spring 1 Steel Mounting Bracket 1 Steel Relief Valve Diaphragm Assembly. 1 - Information in this publication is based on current specifications. The company reserves the right to make changes in specifications and models as design improvements are introduced. Powers is a trademark of 2000 Landis & Staefa Division 1000 Deerfield Parkway Buffalo Grove, IL U.S.A. Your feedback is important to us. If you have comments about this document, please send them to technical.editor@sbt.siemens.com Document No P25 Printed in the U.S.A. Page 10