Monitor for testing the operating condition of a nonreturn valve

Abstract From the Canadian patent

Apparatus for monitoring displacement of translational member in a pressurized vessel. In one form, the apparatus comprises first and second fluid containing compressible bellows each coupled to a differential pressure gauge in order to measure pressure fluctuations between the bellows. An end portion of the first bellows is coupled to the translational member in order to recieve a variable compressive force as the member is displaced. The displacement of the translational member is determined as a function of the pressure variation between the first and second bellows.