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发表于 2017-1-15 20:31:07
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B.6.1.2 Using an aerosol photometer
The aerosol photometer method (B.6.2) may be used for testing:
a) cleanrooms in which local aerosol injection points are provided in the duct distribution system that allow the specified high aerosol challenge concentrations to be achieved;
b) systems incorporating filters with integral MPPS (Most Penetrating Particle Size) penetrations equal to and greater than 0,003 %;
c) installations where outgassing of oil based volatile test aerosol deposited on the filters and ducts is not considered to be detrimental to products and/or processes and/or personnel within the cleanroom.
NOTE The aerosol photometer method is known to create 100 to 1 000 times the aerosol concentration on a filter of the same grade, when compared to the DPC method.
B.6.1.3 Using a discrete-particle counter (DPC)
The DPC method (B.6.3) is more sensitive, and the filter system becomes less contaminated than by using the aerosol photometer method. It may be used for testing:
a) cleanrooms with all types of air-handling systems;
b) systems incorporating filters with MPPS (Most Penetrating Particle Size) penetrations down to 0,000 005 %;
c) installations where outgassing of oil-based volatile aerosol deposited on filters and ducts cannot be tolerated or where the use of solid aerosol is recommended.
选自ISO 14644,从这个来看DPC方法的适用性比较广,灵敏度比较高(一般的H14的MPPS为0.005%,所以两种方法均可以,但是针对于U15,U16,U17的超高效过滤器的检漏,光度计的方法就不适用了),还有由于其灵敏度高其在上游需要的发烟浓度会相对较小,那么这样一来,对产品的质量风险也会相对较低。
还有一个问题,在实际的高效检漏操作中,我们发现光度计法(aerosol photometer)具有专属性,只对于发烟的物质(如PAO)进行检测,而对于空气中其他的粒子的则没有响应;DPC没有使用过,DPC是否对周围所有的particles均有响应呢????@江苏新征鸿净化 @石头968 @意林枫
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