Importance

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Abstract

The pilot valve 206 disclosed utilizes a piston 226 operating intermediate a pressure setting spring 234 and main valve head volume 222 vent valve, and having a single pressure sensing chamber 235. The operating piston includes an elongated extension 229 of reduced diameter extending from the piston adjacent the sensing chamber and incorporates an opposite end, secondary relief chamber 230 providing main valve operation at pressures fixedly related to the operating piston relief setting. The piston extension operates the vent valve 245 in an adjacent chamber. The piston further defines an internal cavity 240 containing a somewhat coaxial inlet valve 251, 252. Inlet and exhaust valves are in fluid communication through said piston extension. Main valve head volume venting and pressurizing is accomplished through valve body ports cooperating with said inlet and exhaust valves. Product backflow, and main valve head volume repressurization are prevented through the use of ported check valves internal of the pilot operating piston.

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First Claim