Two stage pressure relief valve

摘要

A two stage pressure relief valve for releasing a fluid under pressure includes a body having a bore extending from an inlet and terminating in an outlet. A first chamber which communicates with the inlet and a second chamber which communicates with the first chamber and the outlet are provided and are dimensioned such that the cross sectional area of the second chamber is greater than that of the first chamber. An operator seat is disposed within the body and an operator is moveably disposed within the bore and engages the operator seat. The operator includes a blocking surface which blocks at least a portion of the flow of fluid. When the pressure of the fluid exceeds a threshold pressure, the operator is unseated whereby fluid flows at a first flow volume such that at least a portion of the fluid impinges the blocking surface causing the blocking surface to move within the second chamber whereby fluid flows at a second flow volume. The second flow volume being greater than the first flow volume.