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利用经典的分子流、黏滞流、过渡流流导公式及圆管分子流流导几率的精确数值解,对21世纪数篇文献呈现的漏孔流导随上游压力变化关系曲线进行了分析,并将密封器件的漏孔简化为长圆管,得出了以下结论:从流量角度观察气流是否偏离分子流状态是非常不灵敏的,因此可以认为,如果上游压力不超过1×105Pa,对于等效标准漏率L<1.4 Pa.cm3/s的漏孔,气流大致处于分子流状态;当任务允许的L最大值Lmax 14 Pa.cm3/s时,不论L的值是大是小,均不必考虑气流是否偏离分子流状态;仅在压氦法的压氦阶段,当Lmax和L均接近1.4 Pa.cm3/s时,从流量角度气流会处于黏滞流状态,导致合格判据偏保守;而在压氦法的其他阶段和预充氦法各阶段,只要L<1.4 Pa.cm3/s,气流均处于分子流状态。从而证明对于密封器件氦质谱细检漏而言,Lmax取1.4 Pa.cm3/s可以满足气流处于分子流状态的要求,且该值大于粗检的下限。
Based on the classical numerical solution of molecular flow, viscous flow and transition flow, and exact numerical solution of the molecular flow conductivity of circular tube, this paper analyzes the curve of leak flow conductivity in several literatures in the 21st century with the change of upstream pressure. And the leak of the sealing device is simplified to a long tube. The following conclusions are drawn: It is very insensitive to observe whether the airflow deviates from the molecular flow state from the viewpoint of flow rate. Therefore, it can be considered that if the upstream pressure does not exceed 1 × 10 5 Pa, Standard leak rate L <1.4Pa.cm3 / s of the leak, the air flow roughly in the molecular flow state; when the task allows the L maximum Lmax 14Pa.cm3 / s, regardless of the value of L is large and small, are not considered Only when the Lmax and L are close to 1.4 Pa.cm3 / s, the air flow will be in a state of viscous flow only in the helium compression helium stage, which leads to the conservative pass. In the other stages of compression helium and pre-charge helium at all stages, as long as L <1.4Pa.cm3 / s, the gas flow in the molecular flow state. Thus, it is proved that the Lmax is 1.4 Pa.cm3 / s for the helium mass spectrometer leak detection of a sealed device, which meets the requirement of airflow in the molecular flow state, and the value is larger than the lower limit of the coarse inspection.