Page 21 - Parker - The Handbook of Hydraulic Filtration

Filter Media Types and Ratings

The example would read “Beta ten So, in the example, the particular filter
equal to five.” Now, a Beta Ratio tested was 80% efficient at removing 10
number alone means very little. It is micrometer and
a preliminary step to find a filter’s larger particles. For Beta Ratios/Efficiencies
particle capture efficiency. This every 5 particles
Beta Ratio Capture Efficiency
efficiency, expressed as a percent, introduced to the
(at a given particle size) (at same particle size)
can be found by a simple equation: filter at this size
1.01 1.0%
range, 4 were
1.1 9.0%
trapped in the filter
1.5 33.3%
media. The Beta
Efficiency x = 1 2.0 50.0%
(1- ) 100
Beta Ratio/ Efficiencies 5.0 80.0%
table shows some
Efficiency = 1 ) 100 10.0 90.0%
10 (1-
5 common Beta Ratio 20.0 95.0%
= 80% numbers and their 75.0 98.7%
corresponding 100 99.0%
efficiencies. 200 99.5%
1000 99.9%

Beta Ratio

Downstream
Particles Beta Ratio (x) Efficiency (x)
Upstream 100,000
Particles 50,000 = 2 50.0%
50,000

100,000
5,000 = 20 95.0%
5,000

100,000
1,333 = 75 98.7%
1,333
100,000 > (x) microns
100,000
1,000 = 100 99.0%
1,000

100,000
500 = 200 99.5%
500
100,000
100 = 1000 99.9%
100

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