Determination of temperature recovery time in differential-pressure-based air leak detector

Repeatability and accuracy in a differential-pressure-based air leak detector can be increased by providing adequate temperature recovery time to the system after the charging process. However, different volumes and applied pressures need different temperature recovery times. We proposed a method to accurately predict the minimum required temperature recovery time considering repeatability and accuracy of the leak detector by investigating the relation between temperature recovery time and theoretical thermal-time constant for various test volumes and applied pressures. To demonstrate the effectiveness of the proposed method, a differential-pressure-based air leak detector is developed. In this method, a leak is simply detected by measuring the differential pressure between a leak-tight master and a test chamber. The results show that the minimum required temperature recovery time to produce repeatability and accuracy not less than 1.67 x 10(-11) m(3) s(-1) for various applied pressures and volumes is proportional to six times the theoretical thermal-time constant.