"Does the Beta rating of a filter tell you how much dirt a filter can remove? How does Beta compare to a filter that is nominal rated?"

Yes, one section of the Beta rating test procedure of a filter will tell you about the filter's approximate dirt-holding capacity.

If you know only the nominal rating of a filter in microns, this really does not quantify its capture efficiency at that size. For example, if a filter is said to be 6-micron nominally rated, it doesn't describe how likely that particles 6-micron and larger are being retained by the filter.

A better approach is to compare the performance of filters with a Beta Rating (ISO 16889). A Beta rating (of 6 microns for example) is a measure of the number of particles greater than 6 microns upstream of the filter divided by the number of particles greater than 6 microns downstream of the filter.

A Beta rating of 200 means that its capture efficiency is 99.5 percent for a specific micron particle size or greater. Using the above example, for every 200 particles larger than six microns entering the filter, one passes through. In addition to reporting the capture efficiency the test protocol described in ISO 16889 also determines the approximate dirt-holding capacity.

Note, data generated from ISO 16889 are based only on the specific test conditions prescribed by the standard. Actual field conditions may vary considerable.

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