Pilot Operated Safety Valve Descriptions

Pilot operated safety valve is one important protection unit in the pipeline. In the normal closed postion, system pressure is transmitted through the pilot valve and into the dome of main valve. The pressure above the main valve disc generates a net downward force, hold the main valve closed.
When system pressure reaches the set pressure, the pilot spindle lifts and reseat piston closed simultaneously, venting the dome pressure through the pilot valve to atmosphere. Because of system pressure remains above reseat pressure, the reseat piston is hold tightly closed, blocking flow to the pilot valve (the non-flowing pilot valve feature), at this time, the dome pressure of main valve is depressed quickly, allowing the main valve to open fully.
When the desired system pressure is achieved, the pilot spring force overcomes force on the reseat piston, the reseat piston snaps open, and the pilot spindle snaps closed simultaneously. Finally, system fluid reenter the dome and closes the main valve. Flowspec Luokai can manufacture the pilot operated safety valve in accordance with ISO4126, API RP520, JIS8210, DIN3320.