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94640 Pilot Operated Relief Valve (Pressure Diaphragm Pilot)

94640 Pilot Operated Relief Valve (Diaphragm Pilot)
  • Set pressure between .11 to 15 psig

  • Valve sizes 2" x 3", 3" x 4", 4" x 6", 6" x 8", 8" x 10" and 10" x 12"

  • Adjustment of the valve can be made externally

  • Seat is Bubble tight to set pressure

  • Snap action or modulating mode

  • Fully open at set pressure in snap action mode


The Shand & Jurs Pilot Operated Relief Valve is designed to meet very specific pressure needs. The high accuracy of the valve allows the pressure to be set pressure between .11 to 15 psig using sensitive springs for discrete ranges. The valve operates as follows.

As the internal pressure reaches the valves set point, the upward force on the sensing diaphragm overcomes the downward spring force. This causes the pilot seat to slightly lift, resulting in a small release of flow and marginal pressure relief. This enables the large diaphragm cavity to create a large, upward force which fully opens the pilot seat. This causes a large pressure reduction on the upper side of the main valve diaphragm which results in a full lift of the main valve seat.

When the pressure reduces to the point its resulting upward force is less than the spring force, the pilot seat begins to close. This, in turn, builds up pressure on the upper side of the main valve diaphragm which closes the main valve seat. The pressures are again returned to their normal operating levels.

Applications
Meeting emissions standards for process and storage tanks requiring pressure relief

Hot hydrocarbon vapors or liquids, corrosive liquids, gas, cryogenics

Tanker ships, vessels, petroleum, chemical, oil, gas, marine, environmental plants, sanitary, and cryogenic industries. Tank applications operating very close to set pressure

Low pressure safety-relief valve for vessel applications, from general product tank storage to transportation vessels