concentration of the aerosol challenge upstream of the filter

beiwei5du

B.6.2.3 Concentration of upstream aerosol challenge and its verification
The concentration of the aerosol challenge upstream of the filter should be between 10 mg/m3 and 100 mg/m3. Concentrations lower than 20 mg/m3 can reduce the sensitivity for leak detection. Concentrations greater than 80 mg/m3 can give rise to excessive filter fouling over an extended test period[18].
Appropriate measures should be taken for the verification of the homogenous mixing of the added aerosol to the supply airflow. The first time a system is tested it should be determined that sufficient aerosol mixing is taking place. For such validation all injection and sampling points should be defined and recorded.（这个大家都有做吗？？？）
The upstream aerosol concentration measurements taken immediately upstream of the filters should not vary more than ± 15 % in time about the average measured value. Concentrations lower than the average will reduce the sensitivity of the test to small leaks, while higher concentrations increase the sensitivity to small leaks. Further details as to how to conduct the air-aerosol mixing test should be agreed upon between customer and supplier. ASME N510-1989[1] and IEST-RP-CC034.2:1999 [18] may also be of value.


选自：http://www.atitest.com/knowledge-center/faqs/faq003-upstream-challenge-aerosol-introduction-point/
Upstream Challenge Aerosol Introduction Point

To ensure adequate upstream aerosol challenge mixing, it is strongly recommended to introduce the test aerosol at least ten duct diameters upstream of the filter(s) under test（至少在过滤器前10倍管道直径的地方引入检测气溶胶）. If 10 duct diameters is not feasible, or adequate mixing is not obtained, sparge pipes, upstream baffles, turning vanes or a Stairmand disc, located four to six duct diameters upstream, will achieve adequate mixing（这些各位实际的使用中有接触过嘛？？？）.

A Stairmand disk is a plate with the same geometric shape as the duct section blocking the center of the duct area. Air flowing past the disk creates vortices on the leeward side that compel turbulent and thorough mixing of the introduced aerosol and the dilution air stream. The required diameter of the Stairmand disk may be calculated using the following information.

Stairmand disk diameter equals the pipe (or duct) diameter divided by the square root of two (1.414213). Eg. a 12 inch duct would require a Stairmand disk 8.5 inches in diameter.

- See more at: http://www.atitest.com/knowledge ... thash.TNJW9H0j.dpuf

beiwei5du

求这两份文件资料 ASME N510-1989[1] and IEST-RP-CC034.2:1999 ，非常感谢啊！！！

syhorchid

学习一下

胜利者

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