HEPA filters were developed in the early 1940’s during the creationg of the atomic bomb.The use of radioactive materials in the making of the bomb created extreme health hazards for the technicians and engineers that had to handle this type of material. Due the extremely small size of the radioactive particles ( Sub-micron in size ), readily available air filter media like furnace filters, were totally useless in reducing the levels of radioactive particulate. They needed a filter material that could absolutely remove and capture these tiny particles.
After trying a number of materials a process using a wet laid paper type material infused with tiny pieces of glass was used to develop a very dense material that was capable of filtering out these tiny sub-micron particles. The paper like material was formed into an accordian style form with pieces of aluminum sandwiched beteween each folded layer to protect the paper-like media as it was relatively fragile and could abrade by rubbing on itself.
The filter pack was placed inside a square medtal housing and was glued in place. The outside parameter of the metal housing had a neoprene type gasket so when it was placed in a sheet metal duct it would compress the gasket to form a leak-tight seal. These filters had an initial efficiency of capturing 99.97% of all particles 0.3 microns and larger and as it got dirtier its efficiency increased. The use of this HEPA filter allowed the technicians to work in a safer environment culminating in the eventual creation of the two bombs used on Japan to end WWII.
For more information on the complete line of HEPA filtration systems offered by Pure Air Systems please go to our website at: http://www.pureairsystems.com or call us on our toll-free number at: 800-869-8025.