HEPA Filters and Filter Testing A Comparison of Factory Tests and In-Service Tests

HEPA filters, once known as absolute filters, were originally developed as the particulate stage of a chemical, biological, radiological (CBR) filtration/adsorber unit for use by the U.S. Armed Services. In the late 1940s the U.S. Atomic Energy Commission adopted them for use for the containment of airborne radioactive particulates in the exhaust ventilation systems of experimental reactors as well as for use in other phases of nuclear research. The period from the mid 1950s to the present has seen the emergence of many new industrial and scientific technologies requiring particulate free air in order to produce more sensitive products such as microelectronic components, photoproducts, parenteral drugs and dairy products. These technologies fostered the development of a wide range of specialized devices to house HEPA filters to deliver clean air to production areas. Uses for HEPA filters in hazardous containment applications have increased also, and they are more routinely used on the exhaust side of bio-hazard hoods, animal disease research laboratories and whenever airborne carcinogens must be controlled.