对于关键的循环水过滤器工作原理而言,完整性测试是一种必要的手段,以确保过滤工艺的安全性。通过完整性测试,可以确定过滤器自身的完整性及正确安装,可以确保工艺中安装了正确的过滤器,可以确定所安装的过滤器符合制造商提供的标准,还可以确保过滤系统的密闭性等等。同时,进行完整性测试也是各国法规和审计的要求。
分类
破坏性测试
非破坏性测试
起泡点测试
水侵入法测试
扩散流测试
总体而言,完整性测试方法分为两大类,破坏性的和非破坏性的,下面将分别进行介绍。
破坏性测试 对除菌级循环水过滤器而言,破坏性测试是指细菌挑战-testing,该testing方法是证明循环水过滤器能够满足苛刻除菌级标准的一种根本手段。在细菌挑战-testing中,我们需根据统计学原理从每批产品中抽取一定数量样品,并按照标准testing方法(如:ASTM F838-83),利用缺陷假单胞菌溶液(Brevundimonas diminuta ATCC 19146)进行细菌挑战-testing,那些需要达到至少10^7 CFU/cm^2膜表面的细菌截留才可认为该filter为除菌级filter。
非破坏性testig 方法主要包括基于毛细管原理起泡点、水侵入法testig,以及基于扩散原理扩散流和保压testigs。下面分别做一下简单介绍:
起泡点testig 基于毛细管模型。当filter被润湿液体完全润湿后,如果要想将液体挤出膜孔就需要外加一个气体压力。能够克服表面张力将膜孔内液体完全挵出的最小压力,就是我们常说的起泡点,这也是应用最广泛的一种non-destructive testig method。
Water Infiltration Testig HydroCorr testig,又称“挸水法”,“water infiltration test”. This testing method is based on the water in hydrophobic filter membrane surface existing interfacial tension and capillary phenomena development out of it.
In this testing process, we measure the decrease of air pressure at the downstream end of the filter due to water infiltrating into or passing through pores, which indicates whether the filter is intact or not.
WIT (Water Intrusion Test) is a non-destructive online testing method for hydrophobic filters, which measures the rate of decline in upstream air pressure when water infiltrates into a hydrophobic filter membrane submerged in water.
The WIT results are related to pore size and can be used as an indicator of filter integrity according to international standards.
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