Relief Valves Service Application Distinguishing Feature Action:
- Spring-Operated & Pilot-Operated : Both types used for incompressible fluids. (i.e., liquids). Both types used where there is no danger of explosion from overpressure.
- Downward seating, relying on spring pressure to seal.
- “Lifts” upward when pressure is at setpoint.
- Reverse (upward) seating, relying on system pressure to seal.
- Downward acting when pressure is at setpoint, gradually opens.
- Relies on pilot valve to actuate relief action.
Safety Valves Service Application Distinguishing Feature Action:
- Spring-Operated & Pilot-Operated Both types used for compressible fluids (i.e., gases and vapors). Both types used where there is danger of explosion from overpressure.
- Downward seating, relying on spring pressure to seal.
- “Pops” fully open when pressure is at setpoint.
- Blowdown setpoint adjustable
- Downward seating, relying on system pressure and spring pressure to seal.
- “Pops” fully open when pressure is at setpoint.
- Relies on pilot valve to actuate relief action.
Blowdown setpoint adjustable.