Understanding Oil Filter Rankings


“My filter firm makes use of the next notation to price considered one of its filters: BX=2, B10=X, BX=75, adopted by these numbers: 5, 8 and 17. I am conversant in the Beta score, however I’ve by no means seen it proven on this manner. What is supposed by these numbers?”

This technique of score a filter describes its seize effectivity at three particular factors in microns. It really has many benefits over the extra frequent Beta score strategies used as we speak.

That is the way it works:


The “X” denotes the dimensions in microns of particles above which the filter is just eradicating 50 p.c of the particles coming into. For instance, 100 particles bigger than “X” come into the filter, however solely 50 of them are captured. On your filter, this 50-percent effectivity measurement is 5 microns. That is the decrease restrict of efficiency in microns for this filter.


The “X” on this case denotes the Beta ratio akin to particles bigger than 10 microns. Many hydraulic customers previously have considered 10 microns to be a important clearance measurement, above which system parts are at excessive threat of failure. The “X” has to do with the seize effectivity of particles bigger than 10 microns.

In your instance, the Beta ratio at 10 microns is 8, that means that for each 8 particles bigger than 10 microns coming into the filter, one will get by uncaptured (about 88 p.c seize effectivity).


This “X” corresponds to the micron measurement above which the filter is eradicating 98.7 p.c of all of the particles. In different phrases, the Beta ratio for the particle measurement (X) is 75. For each 75 particles bigger than “X” coming into the filter, just one will get by (74 are eliminated).

Many individuals have informally referred to that measurement (X) as “absolute,” though clearly, by definition, it isn’t. Nonetheless it’s helpful to know what the BX=75 score is. In your instance, the “X” corresponds to 17 microns.

Filter testing is accomplished in a laboratory so the outcomes could be in contrast and statistically verified. Filtration assessments try to precisely management the standard of the check mud, the movement charges, temperatures, measuring tools and lots of different variables to make sure the repeatability of the check.

The check, referred to as a multi-pass filter check, produces a Beta score for the filter at a given micron measurement. It’s comprehensible, however nonetheless disappointing, to search out that filters don’t all the time carry out within the discipline precisely because the laboratory assessments would counsel.

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