HEPA filters are commonly used in cleanrooms as an air purifier and to help filter pollutants out of the working environment.
Normally HEPA filters will be tested during the installation but it is also recommended that they undergo periodic routine maintenance and are retested after a filter has been changed. When using high efficiency filters, it is crucial to ensure that the housing / sealing around the device is completely sealed, so not to allow foreign particulate into the cleanroom environment.
Filter Integrity Testing, is historically referred to as a DOP test. This is because the original fog chemical used was Di-Octyl Phthalate. This chemical was later suspected to a carcinogenic so a pharmaceutical grade, white mineral oil is now used with identical results.
The VC Aero fog machine (aerosol generator) is used worldwide by major blue chip, nuclear, pharmaceutical and cleanroom specialists for their HEPA & ULPA filter testing.
For air flow visualisation work we recommend using the portable, water based Mini Colt 4S fog machine. After being pre-heated the fog machine can be unplugged from the mains and used off power, allowing the tester to move around and evaluate the air flows from different perspectives. The Mini Colt 4S can also be ducted allowing users to place the fog where required.