Whitehouse shows novel filter calibration method

Whitehouse Scientific will demonstrate its novel approach to filter testing at Filtech 2005, and will display the range of NIST-traceable glass microspheres used for filter calibration

At Filtech 2005, Whitehouse Scientific will demonstrate its novel approach to filter testing and will have on display standards from the range of NIST-traceable glass microspheres for filter calibration.

This range has recently been extended with the inclusion of standards down to 0.5 micron.

The Whitehouse approach to filter calibration uses glass microspheres in single shot bottles to give a measure of pore size or filter cut point that is traceable to NIST and NPL standards.

The method allows verification of the maximum pore size and can be used on most filter media.

This includes complex and woven media that are impossible to calibrate by other means.

The size range from 1000 to 25 microns is covered by 20 narrow distribution standards.

Calibration at these pore sizes is performed by selecting a standard in the expected pore size range.

The contents of the bottle are weighed and the microspheres are then sifted sonically through a 90 mm diameter disc of the filter under test.

The cut point of the filter is determined from the percentage of standards passing through, using a calibration graph provided.

For pore sizes below 25 microns, a wet challenge test is recommended.

In this case the particle size distribution of the microspheres passing through is measured.

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