体积补偿式正压漏孔校准方法改进分析

针对被校漏孔接头种类繁多,接头漏气难以避免且其值测量不方便的问题。采用两种方式进行修正:一方面利用进退活塞得到两个修正的体积系数,推导出接头漏气和漏孔漏率引起的差压变化之比的测试方法,用以修正接头漏气的影响;另一方面通过粘滞流公式推导出微小压力差下气体漏率与压力差近似成正比。通过调整校准室的压力,利用差分的原理减少漏气对校准结果的影响。两种修正方式的采取,解决了常规漏孔接头漏气难以原位测量或减小到可以忽略的问题,降低了对被校漏孔接头的要求,提升了体积补偿法的测量准确度和工作效率,同时将校准下限延伸到10^-7Pa·m³/s。

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.