| 摘要 |
A vent valve insert comprises a bushing assembly, a piston assembly and a spring. It is designed to fit snugly and sealingly within a suitable borehole, such as the vent borehole of an ECP manifold assembly. The bushing assembly defines a longitudinal bore within which the piston assembly is situated. When pilot pressure is applied to its top surface, the piston assembly is forced to an open position wherein fluid is allowed to flow through the vent valve insert. Absent pilot pressure acting against the top surface, the spring acts to force the piston assembly upward within the longitudinal bore. Secured to the bottom portion of the piston assembly, an annular sealing member is carried upward so that its flat surface seats against a raised inner portion of an annular valve seat. The vent valve insert is thus normally biased to the closed position. The vent valve insert also features a mechanism for preventing non-longitudinal movement of the piston assembly as it is moved longitudinally within the longitudinal bore. The mechanism not only guides the movement of the piston assembly within the bushing assembly but also prevents the bell clapper effect inherent to the vent valve inserts currently used in the industry.
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