Patent ID: 6182501
Filing Date: 2001-02-06
Classification: G01M

Abstract:
A leak test method in which: pressurized gas is introduced into a master and a work connected to a high-pressure gas source via first and second valves, respectively; the pressure difference between said master and said work is measured by a differential pressure sensor; a pressure difference variation per unit time is calculated from a measured value of said pressure difference; a drift is subtracted from said pressure difference variation to obtain a leakage; and said leakage is compared with a leakage reference value to determine if said pressurized gas leaks out from said work; said method comprising the steps of:(a) opening a third valve connected between said work and said master to establish a pressure equilibrium therebetween, and then closing said third valve;(b) measuring a first pressure difference variation per unit time;(c) opening said third valve, after said step (b), to establish a pressure equilibrium between said master and said work, and then closing said third valve;(d) measuring a second pressure difference variation per unit time after said step (c), wherein: said first and second pressure difference variations are measured in a measurement period which is an initial pressure difference variation domain;(e) obtaining an exponential approximate expression of time from said first and second pressure difference variations; and(f) calculating a pressure difference variation as a pressure difference stabilization period subtracting said pressure difference variation from said first pressure difference variation to obtain said drift.