PAO scaning HEPA

How the PAO scaning done for a Plenum HEPA


The leak test requires that the filter gasket, filter frame and filter media are scanned. The media is scanned at nominally 2.5mm from the filter face at a rate not exceeding that given in the standard.

ISOEN14644-3 has made the particle counter and photometry scan test the same speed and this is defined as: “The probe traverse scan rate (Sr) should be approximately 15/WP cm/s. (WP is the width of the probe at 90° to the direction of the scan) For example, when using a 3cm square probe, Sr is 5cm/s.

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Is it acceptable to perform leak test for plenum HEPA instead of scanning?

First of all you have to make sure that above the HEPA filter there is PAO concentration of 20 to 80mcgper litre then that concentration you have to set 100 percent after that below the HEPA filter start the scanning using photometer and and probe , Keep the probe 3 cm below the filter face and start scanning at 5cm per second if during scanning there is any alarm then there is chance of filter leak check the reading from photometer it should be less than 0.01% of initial set, after completion once again check the PAO concentration is within the range or not.