TEST DEVICE FOR PILOT VALVES

摘要

A testing device (22) for a non-flowing pilot valve (20) controlling a main relief valve (13) and simulating the action of the relief valve (13). The testing device body (84) has a test fluid source (42) releasably connected thereto and includes a piston valve element (112) mounted in a valve chamber (106) for movement to an unseated vent position upon the test fluid pressure reaching a predetermined high which is usually similar to the set point operating fluid pressure at which the main relief valve (13) will actuate. For return of piston valve element (112) to a seated position after a reduction of the test fluid pressure by venting, a relatively large diameter end face (128) is exposed to fluid pressure from an intermediate fluid chamber (78) of the pilot valve (20) which is in fluid communication with the dome (14) of the pressure relief valve (13). A relatively small fluid pressure responsive area of piston (113) outwardly of small diameter O-ring (120) is exposed to test fluid pressure.