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Filtration

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thwilli2

Mechanical
Joined
Dec 12, 2002
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6
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US
I there a difference between absolute filter efficiency rating and beta ratio? Is there a ASTM standard related to this subject?

Thanks

Tom
 
The effciency of an absolute rated filter is directly related to the Beta ratio.

Beta ratios are given for specific micron ratings. For example, a B10 = 200 means that a filter has a Beta ratio of 200 for a 10 micron size. a B5 = 200 would have Beta ratio of 200 for a 5 micron size.

The efficiency of the filter is determined by taking the Beta ratio minus one, dividing it by the Beta ratio, and then multiplying by 100. An example for a Beta ratio of B10=200 is --> [(200 - 1) / 200] X 100 = 99.5%. So this filter is 99.5% efficient in removing particles of 10 micron size.

Regards,

Schlebb
 
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