Patent ID: 6189856
Filing Date: 2001-02-20
Classification: F16K

Abstract:
A pressure release valve comprising:a valve body having a port for communicating with a pressurized fluid, and including a cylinder;a piston which is movable in the cylinder between a first position in which it seals the port and a second position clear of the port, the piston being movable to said second position by the pressure of said fluid;vent means in the valve body communicating with said port when the piston is in its second position, for venting of said fluid from the valve;said piston forming part of a differential piston assembly which also includes a fixed piston element carried by said valve body, said piston element and piston together defining a chamber which has a maximum volume when the piston is in its first position and a minimum volume when the piston is in its said second position, for receiving a cushioning fluid;means for controlling flow of said cushioning fluid out of the chamber so as to cushion movement of the piston towards its second position; and,piston actuating means maintaining the position in its said first position when the port is to be sealed, said actuating means being releasable to allow the piston to move to its said second position under the influence of said pressurized fluid when the pressure of the fluid is to be released.