聚四氟乙烯密封圈密封性能研究

Influence of Helium Permeation in Polytetrafluoroethene Gasket on Leak Detection

试验研究了聚四氟乙烯密封圈压缩量、检漏时间等因素对密封性能的影响;利用数值模拟方法研究了氦气在聚四氟乙烯密封圈中的渗透过程及密封圈尺寸对该过程的影响;分析探讨了含氦渗透率较高材料容器的检漏问题。研究结果表明,试验中容器检漏测得的漏率主要是聚四氟乙烯密封圈对氦气的渗透产生的,充氦到检漏之间的时间过长使得氦渗透漏率较大,导致容器的漏率不能满足设计指标;缩短充氦到读取检漏值的时间,在氦气还未渗透通过密封圈前就检漏可获得界面、漏孔泄漏导致的漏率,增大密封圈渗透方向的厚度可显著增加该时间。

The effect of the propellies of polytetrafluoroethene （FIFE） gasket,including but not limited to the com- pression ratio, leak-detection time, dimension, and permeation rate of helium, on helium leakage rate of the vacuum vessel was experimentally investigated with He leakage detector. The dependence of helium permeation of PTFE gasket, tens of time higher than that of other nonmetal gaskets, on the He-leakage rate was approximated, modeled, and simulated. The re- suhs show that the high He-permeation rate in FIFE has a significant negative impact on leakage detection and on evalua- tion of sealing performance of PTFE gasket. For example, a longer He-filling and leak-detecting time resulted in a much higher He-leakage rate. To detect the realistic leaks at interfaces and orifices, He-permeation in FIFE should be consider- ably reduced by shortening the leak-detection time and by increasing the He-diffusion path in FTFE gasket.