A relative calibration method for a valve leakage rate measurement system

This paper presents a relative calibration method for an internal valve leakage rate measurement system using both microcontroller and acoustic emission (AE) methods. An air jet was selected to calibrate because it provides a frequency spectrum similar to the AE spectrum obtained from the valve leak, especially in the frequency range of 100–300 kHz. Three AE sensors mounted on a valve were used to validate the system calibration. Ratios between the average energy (AErms) were obtained from each pair of sensors, and these ratios were used to transfer the leakage AErms value. Subsequence, its performance to predict the leakage rate in the laboratory and in the field was tested. The error is less than 5% in almost cases. Its benefit is to reduce the recalibration time when a part of measurement system is changed. Accordingly, inexpensive equipment including an AE sensor was built, and its system performance was revealed.