Leak-Rate-Quantification Method for Gas Pressure Seals with Controlled Pressure Differential

An enhancement to the pressure-decay leak-rate method with mass-point analysis solved deficiencies with the standard method. By adding a control system, a constant gas pressure differential across the test article was maintained. As a result, the desired pressure condition was met at the onset of the test, and the mass leak rate and measurement uncertainty were computed in real time. Data acquisition and control systems were programmed to automatically end the test when specified criteria were met. Typically, the test was stopped when a specified level of measurement uncertainty was attained. Using silicone O-ring test articles, the enhanced method was compared with the standard method that permitted the downstream pressure to be nonconstant atmospheric pressure. Two example cases were presented: one case had a low leak rate, whereas the second leak rate was three orders of magnitude higher. The two methods recorded comparable leak rates, but the enhanced method resulted in significantly lower measurement uncertainty, statistical variance, and test duration. Utilizing this enhancement in leak-rate quantification, projects will realize reduced cost and schedule, improved test results, and easier interpretation between data sets.