The Effect of Temperature Recovery Time on the Repeatability of a Differential Pressure Type Air Leak Tester

Abstract

Differential pressure type air leak testers are widely used in industry due to their suitability for automation, low manufacturing cost, accuracy of 2% FS and applicability for leaks as small as 1.7×10-10m3/s. We developed a differential pressure type leak tester, modified the circuit and investigated its characteristics. In the previous differential type air leak tester, the temperature recovery time was set to be constant for various test pressures and volumes. We found that different test pressure and volume required a different temperature recovery time to obtain the expected repeatability and accuracy. Detailed investigation showed that the higher the test pressure and the bigger the volume, the longer temperature recovery time was required to obtain the expected repeatability and accuracy. We also demonstrated the effect of temperature recovery time on repeatability by comparing the normal chamber and copper wire stuffed isothermal chamber. The result showed that the copper wire stuffed isothermal chamber suppressed uncertainty.