The Truth About HEPA Filters
Hepa filters have been around since the development of the atomic bomb. In fact, HEPA paper or HEPA media was created in 1941 specifically to remove the Alpha particles in the air to protect the scientists during the actual creation of the first atomic bomb in Los Alamos, New Mexico.
The development of the HEPA filter allowed for the complete capture of sub-micron particles. HEPA actually stands for High Efficiency Particulate Air or Absolute. Meaning it will absolutely remove particles of a certain size.
To be called a true HEPA filter, it has to meet a minimum capture filtration efficiency of 99.97% at 0.3 microns. To give you an idea of how small this is, a strand of your hair is approximately 100 microns in diameter. You can see particles only down to about 20 microns in diameter with the naked eye. The capture efficiency means that for every 10,000 particles in the air at 0.3 microns or larger that pass through the HEPA filter, only 3 particles may get through.
Of all the air filters available on the market today, including all the furnace and commercial HVAC filters, only HEPA filters are actually rated on their particulate removal performance. All other filters are now based on a MERV rating scale which gives a general capability based on a particle size range.
HEPA filters are the ONLY type of filter used in the following applications; hospital surgery rooms, micro-chip manufacturing, pharmaceutical manufacturing, food processing, optics manufacturing, isolation rooms for pathogen contamination control, the CDC, Clean Rooms and Biological Laboratories to mention a few.
Over the years a large number of medical product manufacturing companies have latched on to the acceptance of HEPA as the best method for removal of bacteria and viruses and incorporated these filters into their systems. Today, HEPA filters are used in hundreds of commercial applications where the removal of small, sub-micron particles are required.
Unfortunately because of the acceptance of HEPA as THE filter media to use, many air filter companies and vacuum cleaner companies have incorporated the HEPA name into their filtering devices. In most cases these are HEPA type or HEPA like filters and not true, certified HEPA filters.
HEPA filters are extremely expensive when compared to a standard duty media filter; in many cases 15 to 20 times more expensive. In addition, in order for a true HEPA filter to be effective, it must be sealed tightly in the filter frame or holding frame. To ensure this complete seal, HEPA filters use neoprene gaskets on the downstream side and are compressed into the frame to ensure a tight seal. In some cases a gel seal material is used to ensure no leakage around the filter itself.
Compared to general duty media filters and furnace filters, HEPA filters have an extremely high resistance or pressure drop. This means the HEPA filter has to be mated with a more powerful motor/blower system to overcome the additional static load.
Pure Air Systems has been using true, commercial grade, certified HEPA filters since 1985. It has more HEPA systems in the residential and commercial markets as packaged HEPA systems than any other filter company in the US. Today, Pure Air Systems uses a metal framed, high capacity, certified 99.99% at 0.3 micron filter in all of its units.
For more information on Pure Air Systems, HEPA filters and the applications that use HEPA go to our website at: www.pureairsystems. com