| FILTER RATING SYSTEMS |
| FILTRATION RATING TERMS |
| Nominal |
An arbitrary value assigned
by the filter manufacturer, based upon removal of a certain
percentage of all particles of a given size or larger. A nominal
rating of 98% means that 98% (by weight) of the contaminant
of the stated size has been removed. |
| Absolute |
The diameter of the largest hard spherical particle that
will pass through a filter under specified test conditions.
It is an indication of the largest opening in the filter element.
|
| Beta Rating
|
The ratio of the number of particles
present in the influent fluid to the number of particles present
in the effluent fluid. For example, a fluid passed through a
5µm filter having two particles 5µm or larger going into the
filter, and one particle coming through the filter, is said
to have a Beta rating of 2/1 at 5 micron, expressed Beta5 =
2. |
