| 摘要 |
An upright cylindrical valve body has an inlet port axially aligned with an outlet port. A valve member is retained for reciprocal movement into and out of engagement with a valve seat axial aligned with fluid flow between the inlet and outlet ports. A relief port positioned adjacent to the outlet port exhausts fluid that remains in the valve above the valve seat after it is closed. The valve member is normally maintained in a closed position. Fluid flow into the inlet port actuates the valve. A portion of the fluid flowing through the valve chamber is diverted through passageways by a pair of remote controlled solenoid valves to open the valve. When it is desired to close the valve, the solenoid valves are actuated to evacuate fluid internally within the valve so that the valve member is returned to a closed position. A relief valve in the outlet port exhausts fluid from the upper end of the valve when the fluid pressure falls below a preselected magnitude. Flow through the valve is incrementally controlled by pulsing or cycling movement of the valve member into and out of engagement with the valve seat by switching the solenoid valves between on and off positions. In the closed position of the valve, all fluid is automatically exhausted from the valve.
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