Parker A2B-DN Manual
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Refrigerating Specialties Division 1COMPACTPRESSURE REGULATORSType A2B-DN, A2A-DN, A2BK-DN,A2BOE-DNFOR AMMONIA, R12, R22, R502AND OTHER COMMON REFRIGERANTSFEATURES• Compact Direct Diaphragm Operated• Design Pressure(PS): 28 bar (406 PSIG)• Flanged Connections: FPT, SW, WN or ODS• Available with Close Coupled Strainer• Stainless Steel Diaphragm• Complies with Pressure Equipment Directive 97/23/ECBULLETIN DN21-02BType A2B-DN, A2A-DN,A2BK-DN, A2BOE-DNJanuary 2007Installation and Service InformationDescriptionThe A2 Type pressure regulators are compact, direct diaphragm operated,for use with refrigerant liquid or vapor. The regulators can be used withammonia, R12, R-22, R-502, certain other refrigerants, oil and otherapproved fluids with similar pressure temperature and corrosioncharacteristics. The design pressure is 27.6 bar (400 psig). The regulatorsare for use in systems where a small inlet or outlet pressure regulator isneeded.The regulators are furnished with flanges for FPT: Internal NPT (USAStandard Taper Pipe Thread), socket weld, weld neck or ODS (soldersover copper tubing of given external diameter) connections. Theregulator can be easily removed for service.A strainer can be furnished to close couple to the inlet of the regulator.PurposeThe A2B, A2BK and A2A are Inlet Pressure Regulators that prevent inlet(or upstream) pressure from falling below set-point. They will tend to openon a rise in inlet pressure above set-point and will be closed below set-point.The A2BO and A2BOE are Outlet Pressure Regulators. (The A2BOEsenses outlet pressure through an external connection.) They prevent theiroutlet (or downstream) pressure from rising above set-point. They tend toopen on a drop in outlet pressure below set-point and will be closed aboveset-point.Principles of Operation A2B, A2AThe inlet pressure acts on the diaphragm; when the force created by thepressure exceeds the force of the range spring, the diaphragm is lifted offof the valve seat and flow occurs between the diaphragm and the valveseat, from the regulator inlet to the outlet. Increased inlet pressure liftsthe diaphragm further, allowing increased flow. Decrease in inlet pressurecauses the diaphragm to move closer to the valve seat, thus reducing theflow. Thus, the regulator acts to maintain the inlet pressure approximatelyconstant. If the inlet pressure drops below the regulator setting, thediaphragm closes off the flow to keep the inlet pressure from going belowthe set point, subject to limits of seat leakage tolerance, or leakage due todirt particles on the seat surfaces.Adjustment A2B, A2AAn accurate pressure gauge should be installed at the gauge connectionon the regulator or in the piping near the regulator inlet.Carefully remove the seal cap by barely cracking it open to allow anyconfined refrigerant to escape gradually. Then turn the adjusting stem in(clockwise) to raise the set point, or out (counterclockwise) to lower theset point. Table 1 shows the set point pressure ranges for the regulators.Do not attempt to exceed the rated maximum pressure setting adjustmentbecause this could damage the regulator or make it inoperative. Severeoveradjusting could also apply enough force to damage the diaphragmand valve seat or put the spring in solid position. So, if the maximumtightening adjustment has been reached, stop and back out the adjustingstem (counterclockwise) at least one half turn so the range spring canmove.After adjusting the regulator it is advisable to observe the maintainedpressure while the system is operating normally and to make any minoradjustments required at that time. Replace the seal cap after the desiredset point is reached.TABLE 1. INLET PRESSURE SETTING RANGESAPPROX. CHANGE PER TURNSET POINT RANGES OF ADJUSTING SCREWA: 0 to 10.3 bar (0 to 150 psig) 1.7 bar (25 psi)V: 500 mm Hg to 8 bar(20 in. Hg to 120 psig) 1.7 bar (25 psi)D: 5 to 19 bar (75 to 280 psig) 3.6 bar (53 psi)I S O 9 0 0 1 C E R T I F I E DFIG. 1 – A2B-DN and A2A-DNSEAL CAPADJUSTINGSTEMRANGE SPRINGDIAPHRAGMVALVESEAT73mm (2.9")117mm (4.6")1/4" NPTGAUGEPORT173mm(6.8")211mm(8.3")FITTINGFOR A2BP1/4 N.P.T.310211 |
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