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Pilot operated diaphragm valve

  • US 4,135,696 A
  • Filed: 11/01/1976
  • Issued: 01/23/1979
  • Est. Priority Date: 11/01/1976
  • Status: Expired due to Term
First Claim
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1. A valve assembly for controlling liquid flow, said valve assembly including:

  • a casing defining an inlet and an outlet, and also defining a valve chamber, an auxiliary chamber, and a conduit interconnecting the valve chamber and the auxiliary chamber, said auxiliary chamber having a discharge port for discharging liquid from said valve chamber and from said auxiliary chamber;

    means defining a bleed port for introducing liquid into said valve chamber;

    a valve actuator movable in said valve chamber between a first position in which the valve defines an open path between said inlet and said outlet, and a second position in which the valve closes said path;

    a diaphragm supporting said valve actuator in said valve chamber and providing a seal for said valve chamber;

    a solenoid operated valve positioned in said auxiliary chamber and including a plunger extending into said discharge port to permit the discharge from the valve chamber when the pilot valve is in an open position so that there is insufficient pressure exerted on the valve actuator to hold the valve actuator in its second position thereby normally to establish the valve actuator in its first position;

    a valve seat positioned in said discharge port, and said plunger having a distal end positioned to seat against said valve seat when the pilot valve is closed, said pilot valve serving to block the flow of liquid through said discharge port when closed so as to cause a pressure build-up in said valve chamber causing said valve actuator to move to its second position; and

    an outlet line coupled to said discharge port and to the inlet of a pump to discharge liquid from the discharge port to a point independent of said valve outlet so as to establish a material pressure differential across the diaphragm independent of pressure differentials in the liquid flow through the valve so as to obviate instability at low flow rates.

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