Why should HEPA filters be tested?

HEPA filters are installed in the Filter Box by clamping. When installing, the filter may be damaged or the sealing strip may fail because of impropriate installation. A damaged surface or broken seal can cause a leak. These leaks could allow the transmission of contaminant particles that would be unacceptable in a critical application.
To maintain the proper functioning of your filters, your facility should conduct testing and regular maintenance.

• ISO 14644 Cleanrooms and associated controlled environments
• GMP ——Good manufacturing practice of medical products
  
  

How to do the HEPA filter testing?

The most common and popular HEPA filter testing method is the "Aerosol Photometer Method."

Leakage testing involves comparing the concentration in upstream of the filter to the concentration in downstream. It is essential to measure the upstream concentration of the introduced aerosol. 

Upstream –Aerosol Generator and Photometer

Cold aerosol challenge (PAO) is commonly utilized for scanning filters to detect leaks. PAO aerosol is produced using an aerosol generator with Laskin nozzle. Then test the upstream concentrations by using an aerosol photometer.

The ISO 14644-3 standard recommends concentrations between 1µg/l and 100µg/l for aerosol photometer method. Lower concentrations reduce sensitivity, while higher concentrations increase the chance of fouling the filter. 

               Aerosol Photometer ZR-6012   &  Aerosol Generator ZR-1300A

Downstream –Aerosol Photometer
Using an aerosol photometer to detect the concentration of aerosols downstream of the filter to determine if there is leakage in the filter.