Pressure variation detecting type leakage inspection system with temperature compensation

Claim 1

Pressure variation detecting type leakage inspection equipment comprising: pressure measuring means for detecting a variation, in a fixed period of time, in the pressure difference between an article under inspection and a reference tank; an A-D converter for converting the measured pressure difference into digital pressure difference data; first temperature measuring means for detecting the temperature of said article under inspection; second temperature measuring means for detecting the temperature of said reference tank; temperature difference producing means for producing digital temperature difference data representative of the difference between the temperatures of said article under inspection and said reference tank; memory means for storing said pressure difference data in relation to said temperature difference data; readout means for reading out of said memory means all the pressure difference data which corresponds to the temperature difference data from said temperature difference producing means; calculating means for calculating a mean value of the pressure difference data read out of said memory means by said readout means; correcting means for subtracting the mean value obtained by said calculating means from the pressure difference data produced by said A-D converter to provide corrected data; judging means for comparing the corrected data from said correcting means with a reference value to judge whether said article under inspection is nondefective or defective; display means for displaying the results of the judgement by said judging means; write-in means for writing, when said article under inspection is judged to be nondefective by said judging means, the pressure difference data from said A-D converter into said memory means in relation to the corresponding temperature difference data from said temperature difference producing means; and control means for controlling the operations of said readout means, said write-in means, said calculating means, said correcting means, said judging means and said display means.