正压外壳保护性能试验研究

Experimental Study on Protection Performance of Pressurized Enclosure

针对正压外壳防护形式被企业广泛应用于防火防爆的危险场所中,选取了一款正压外壳型保护产品,设计了一套正压测试试验平台,对产品的保护性能展开了研究。通过测量正压外壳的泄漏流量,为运行过程中保护气体的容量补偿提供了依据。两次换气试验分别选取二氧化碳和氦气作为试验气体,氦气得益于相对分子质量与空气相差更悬殊,测试标准要求较低的特点,相比二氧化碳更容易被空气置换。正压外壳内试验气体经换气试验后在不同位置处残留的气体体积分数分布不均匀,外壳内半封闭的小室和角落处浓度高,是保护最不利的点。在产品设计和运行维护中,应加强对最不利点的监控,消除安全隐患。

As the pressurized enclosure is widely used by enterprises in fire and explosion proof dangerous places,a pressurized enclosure product is selected and a set of test platform is designed to study the protection performance.By measuring the leakage rate of the pressurized enclosure,it provides a basis for the compensation capacity of the protective gas during operation.Carbon dioxide and helium are selected as test gases in the two purging tests respectively.Helium is easier to be replaced by air due to the fact that the relative molecular weight is more different from that of air and the test standard requires lower.After the purging test,the residual gas mass concentration in different positions in the pressurized enclosure is not evenly distributed and the semi-closed chamber and corner of the enclosure have higher gas concentration,which is the most unfavorable point for protection.In product design and operation maintenance,the monitoring of the most unfavorable point should be strengthened to eliminate safety risks.