What is a HEGA?
To be called a High Efficiency Gas Adsorber (HEGA), the adsorber must exhibit a minimum mechanical efficiency of 99.9% when tested in accordance with the Institute of Environmental Sciences designation: IES-RP-CC-008-84, “Recommended Practice for Gas Phase Adsorber Cell.” In addition, the adsorber must be designed, built, filled and packaged in accordance with the intent of this standard. Since HEGA filters are manufactured in several different sizes and of several different materials, this standard is not always followed to the letter. It is the intent of the standard and the resulting performance of these adsorbers that is important. This type of adsorber is not intended to be used in odor control systems. However, if the user needs a very efficient odor control system and can justify the higher initial and operating costs, then this type of adsorber will do an excellent job. The following comparison between an odor control type adsorber vs. a HEGA may help:
An odor control type adsorber compared to a HEGA is like comparing an ASHRAE type particulate filter to a HEPA. The odor control type adsorber (like the ASHRAE type particulate filter) has a low efficiency, low pressure drop and low cost. On the other hand, the HEGA (like the HEPA) has a higher efficiency, higher pressure drop and higher cost. Both adsorbers have their place in industry, but because of these major differences they are not usually interchangeable.
Where are HEGA’s Used?
HEGA’s are most often used in “containment” air filtration systems (BI/BO). Containment air filtration systems are very high efficiency systems, used to filter and contain dangerous particulate and/or gaseous contaminants. Containment systems are most often designed to treat exhaust air from contaminated spaces, but occasionally are used in supply and recirculated air systems. Examples of facilities using these systems are:
• Nuclear Power Plants
• Cancer Research Laboratories
• Toxicology Laboratories
• Animal Disease Research Facilities
• Chemical Agent Research Facilities
• Bomb Shelters (CBR)
• Radiopharmaceutical Plants
• HVAC Systems
• Laboratories Using Chemical Carcinogens
• Chemical Agent Munitions Disposal Facilities
• Hospital Isolation Suites
• Pharmacological Facilities
• Chemical Process Facilities
• Military Facilities
• Biological Research Facilities
• Department of Energy Facilities
How Does a HEGA Work?
A High Efficiency Gas Adsorber (HEGA) filters gaseous contaminants from an airstream by adsorbing the contaminants. With a properly designed system that includes proper adsorber selection, adsorbent and resident time, any adsorbable contaminant can be filtered and contained.