Improved and Analysis of Pressure Leak Calibration Method of Volume Compensation

Joint leakage is difficult to avoid,and its value is inconvenient to measure due to so many types of joints of leaks to be calibrated. Two methods were used to make corrections. One way,to correct the leakage of joint,the ratio of the difference of differential pressure caused by the joint leakage and the leakage rate of the leak was derived by pushing the piston forward and pushing the piston back,which obtained two corrected volume coefficients. Another way,the viscous flow formula was used to deduce that the leak rate is approximately proportional to the pressure difference at a small pressure difference. The differential principle was used to reduce the influence of air leakage on the calibration results by adjusting the pressure of the calibration chamber. The adoption of the two correction methods solves the problem that the leakage of conventional leak joints is difficult to measure in situ or reduce to negligible,reduces the requirements of the joint of leak to be calibrated,improves the measurement accuracy and efficiency of volume compensation method,and extends the lower calibration limit to 10^-7 Pa·m³/s.