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To better understand the valve, and how it can be used in applications, please see the following definitions.

Pressure Safety Valve (PSV) A pressure safety valve actuated by inlet static pressure and characterized by rapid opening or rapid popping action.  This safety valve is tight shut-off and is for safety only.  Meets ASME SEC. VIII (Not a Fulflo valve)
Pressure Relief Valve (PRV) A pressure relief device designed to re-close and prevent further flow after normal conditions have been restored. (Fulflo)
Relief Valve (RV) A spring loaded pressure relief valve, actuated by the static pressure upstream of the valve.  The valve opens normally in proportion to the increase in pressure over the set pressure. (Fulflo)
Safety Relief Valve (SRV) A pressure relief valve characterized by rapid opening or pop-action in direct proportion to the pressure increase, depending on the application. (Fulflo)
Conventional Safety Relief Valve (CSRV) A spring-loaded pressure relief valve whose performance characteristics are directly affected by change in the backpressure of the valve. (Fulflo)
Backpressure The pressure existing at the outlet of a pressure relief valve, due to the pressure in the discharge system.  The pressure can be constant or variable.  It is the sum of the superimposed and build-up pressure.
Cracking Pressure The pressure which the valve starts to leak flow through the valve, but before the set pressure.
Set Pressure The inlet pressure the valve is adjusted to open, maintain or control under service conditions.
Differential Set Pressure The pressure differential between the set pressure and constant superimposed backpressure.
Superimposed Backpressure The static pressure existing at the outlet of the relief device at the time the device is required to operate.  It is a result of pressure in the discharge system coming from another source.  This pressure may be constant or variable.
Overpressure The pressure increase or accumulation above the set pressure when the valve is discharging flow.

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