The Pilot-operated Safety Valves are widely used in various industries for liquid and gas release as well as for vapor. They conform to the highest process requirements. Taking into account high requirements to capacity, one pilot-operated safety valve can replace several spring safety valves, which considerably reduces projects' cost. In terms of configuration, the pilot-operated safety valve consists of a main valve and a pilot valve. The pilot valve responds to changes and, using the system pressure, manages the force applied to the upper surface of the main valve spool. Thus it ensures that the valve is sealed when closed, until the time when the system pressure exceeds the preset pressure value. If the preset pressure is exceeded, the pilot valve ensures the release of pressure force applied to the upper surface of the main valve spool. Thus it ensures the main valve opening. If the system pressure is reduced to the value below the preset one, the pilot valve ensures that the pressure force is applied to the upper surface of the main valve spool, thus providing the main valve closing and sealing.
The pilot-operated safety valve has two opening modes:
full-lift means fast and full spool lift at preset pressure excess
proportional lift means spool gradual lift proportional to pressure excess above the preset value