Typical, commercial-grade, activated carbon air filters are designed to remove many common vapor contaminants but they are not designed to effectively protect against many deadly CBRN agents that could potentially be used during acts of terrorism. The full range of CBRN agents can only be effectively removed by using filters with specially treated carbon.
- A carbon adsorption filter removes molecules from the airstream by the process of adsorption, trapping molecules in the pores of the carbon granules
- The most effective activated carbon adsorption filter medium to protect against the effects of toxic CBRN agents is a highly activated carbon impregnated with metal salts and an alkaline solid, trietheylenediamine (TEDA)
- The two most common metal impregnated carbons used in the western world are ASC-TEDA (copper-silver-chromium-TEDA) and ASZM-TEDA (copper-silver-zinc-molybdenum-TEDA) military-grade activated impregnated carbon
- ASC-TEDA is no longer used in the U.S. due to its chromium content
- ASZM-TEDA, patented by the U.S. Army, offers the best chemical protection available. It is the only grade of carbon deemed acceptable for collective and personal CBRN protection systems and devices by the U.S. Army.
- No other filters provide protection from as wide a range of chemical and biological threats as HDT filters and filter systems
- Through HDT’s Applied Research Center, and joint development and testing efforts with the U.S. Army, HDT continues to develop effective filtration technology to protect against an even wider range of chemicals, including the most common and dangerous Toxic Industrial Chemicals/Toxic Industrial Materials (TIC/TIMs)
- All HDT filters (developmental and production) are tested by the U.S. Army Edgewood Chemical Biological Center (ECBC), the nation’s principal research and development resource for non-medical chemical and biological (CB) defense
- Filters can be ordered with specialized media for custom applications
HEPA Particulate Filters
High Efficiency Particulate Arrestance (HEPA) filters were developed by the Atomic Energy Commission during World War II to remove radioactive dust from their plant exhaust. HEPA filters are now the primary filtration systems for electronic clean room assembly, isolation wards, surgical theaters, bioengineering, pharmaceutical processing and any application where maximum reduction or removal of sub-micron particulate is required.
- HEPA filters maintain efficiency over a lifespan of two to five years, depending on operating conditions. As specified by HDT, they are 99.97% effective by particle count, down to an average of 0.3 microns (including bacteria, fungi and other opportunistic micro-biologicals), which is 1/75,000th of an inch or 1/300th the diameter of a human hair. They become even more effective below the 0.3 micron particle size due to decreased face velocity of the particle slamming into the surface of the filter material.
- All HDT HEPA filters are leak tested according to industry and military standards. This is the most reliable method of challenging a HEPA filter system against an aerosol. It measures and compares the downstream concentration to the upstream concentration of the aerosol to determine the system penetration. It must be <0.03%.