Definition of Pressure-Relief Terms

Set Pressure the set pressure, in pounds per square inch gauge, is the inlet pressure at which the safety or relief valve is adjusted to open [10,13]. This pressure is set regardless of any back pressure on the discharge of the valve, and is not to be confused with a manufacturer s spring setting. 

Overpressure pressure increase over the set pressure of the primary relieving device is overpressure. It is the same as accumulation when the relieving device is set at the maximum allowable working pressure of the vessel [10]. 

Applied Process Design for Chemical and Petrochemical Plants 

17 SEAL, NOZZLE B 1C—BUNA-N B3C—BUNA-N 81S—TEFLON-833—BUNA-N  

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