Baldwin Filters

Common Industry Terms IV

June 2015

The filtration industry uses industry-recognized terminology to communicate information relative to filters. What type of filter is it? How does it work? What components are included within the filter and what does that tell us? What are the performance levels of the filter itself? These terms help us to understand the characteristics of all filters, regardless of brand.

Here are a few common industry terms relative to filtration.

AC Flow
A lab test to measure and compare porosity of filter material. A measured amount of test fluid is timed as it flows through a 1", 2" or 3" diameter piece of material. The test is used for quality control and to compare filter materials. The information is stated as how many seconds it takes to flow one liter of fluid through the media.

Bubble Point Test
A lab test to measure porosity in order to rate and compare filter media materials. A sample of filter material to be tested is placed in a fixture and covered by one inch of test fluid. The underside of the fixture is open and attached to a line of air pressure. The pressure required to push an air bubble through the material and fluid is the bubble point. The measurement is stated in inches of water.

Coulter Porometer
Computerized test used to determine the porosity of a given media sample. Actual pore sizes can be determined for entire filter media. Usually given as minimum, maximum and mean pore sizes. This test is used to determine micron ratings.

Frazier Test
A porosity test using an air flow device. Air is pulled by a vacuum pump through the material to be tested and then through a specifically sized opening. The volume of air flow is measured while the restriction is held constant. This test provides a means to compare performance of several materials. This is a quality control test. The information is stated as cubic feet per minute (CFM).

Gurley Stiffness Test
A lab device to measure the resistance to bending or folding of a material. The measurement is stated as milligrams of force.

Mullen Burst Test
A device to measure the force (in pounds per square inch) required to burst a given area of filter material.

We will include additional terms in future editions of Tech Tips.

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