Beta ratio designation for filters efficiency
is a part of the standard multipass test described in ANSI 93.31. Unlike previous
efficiency methods that relied on weight determination, the Beta Rating uses particle
counting for efficiency rating, and is more accurate. The Beta Rating is the number of
upstream particles of a given size divided by down stream particles of the same size.
| Beta Ratios:
Bmicron =
Nx (particle count upstream) / Ny (particle count down stream) |
From this data the element efficiency can be
calculated as follows:
| Efficiency Rating %
= Nx - Ny / Nx x100 = 100 - (100 / Bmicron) |
The
beta ratio is a formula used to calculate the filtration efficiency of a particular fluid
filter using data obtained from multi-pass testing. Multi-pass testing is endorsed by the
National Fluid Power Association, the American National Standards Institute (ANSI), and
the International Standards Organization (ISO) as the most reliable procedure to measure
liquid filtration effectiveness.
Example: 5 micron particles
were fed into a liquid stream and particles counted upstream were 127,000. The 5 micron
count downstream from the filter was 5,000.
The
efficiency of the element would be:
| B5 = ( 127,000 / 5,000 ) = 25.4 Efficiency % = 100 - (100 / 25.4 ) = 96% |
Significance
of (B) beta value in particle count control:
| Bx |
% OF PARTICLES REMOVED |
| 1.0 |
0 |
| 1.5 |
33 |
| 2.0 |
50
(nominal rating) |
| 10.0 |
90 |
| 20.0 |
95 |
| 50.0 |
98 |
| 75.0 |
98.7
(absolute rating) |
| 100.0 |
99 |
| 200.0 |
99.5 |
| 1000.0 |
99.9 |
BETA
75 VS. BETA 200
Originally,
the PALLTM Corp. used the letter 'U' in their nomenclature.
The media was rated Betax = 75 (98.7% efficient.)
Example HC9600FUP8H
The
above element was rated Beta3 = 75, meaning it had an
absolute rating of 3 micron.
Next,
PALLTM then introduced media
designated 'D.'
Rated Betax = 200, and was 99.5% efficient
at the given micron rating.
Example: HC9600FDP8H
Important
note: A difference of .8%! (Less than 1% difference
between an element with a Beta Rating of 75 and one with a Beta Rating of 200.) Good
marketing strategy with no significant increase in performance.
Then PALLTM introduced the 'K' media.
Example: HC9600FKP8H
Also
rated at Betax = 200. This version did away
with the rigid outer wire mesh support and replaced it with a nylon screen and an outer
spiral wrap. We think it reduced manufacturing costs and the life of the element.
FILTER-MART
uses a specially designed filter media with a low initial
differential pressure supported inside and outside with strong wire mesh screen. What is
the advantage? Longer element life.
PALLTM is a Trademark of Pall
Corporation
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