Air filter testing in a changing world

M. Stillwell*, A. Large, Particle Technology Ltd, UK

Test standard EN 779:2012 (1) has been superseded by the new standard ISO 16890:2016 (2). An important part of both standards is to measure the minimum efficiency of a filter, which is also referred to as the ‘discharged efficiency’.

The method described in the new standard is potentially a more reliable way of discharging a filter, and the efficiency measurement obtained is a better representation of reality because an actual filter element is tested as opposed to flat sheet media.

The aim of this work is to investigate how the efficiency of an air filter changes when exposed to IPA vapour for different lengths of time, and to consider how comparable results are between the new method of IPA vapour exposure under ISO 16890, and the old method of IPA liquid exposure under EN 779.

Four gas turbine cylinder cartridge filters were subjected to initial pressure drop and initial efficiency measurements as per EN 779. Subsequently the filters were discharged inside an IPA vapour cabinet for different times for up to 24 hours, before repeat measurements of filter pressure drop and efficiency were made.

This piece of work has drawn the following conclusions...

Session: G8 - Filter Classification and Standardisation
Day: 14 March 2018
Time: 13:00 - 14:15 h

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