SCIENCE

To understand how Steril-Aire UVC works, it is important to understand the science behind UVC.

The C wavelength of the UV spectrum (UVC – 253.7nm) targets the DNA of microorganisms, destroying their cells and making replication impossible. Directed at a cooling coil or drain pan, UVC energy destroys surface biofilm, a gluey matrix of microorganisms that grows in the presence of moisture. Biofilm is prevalent in HVAC systems and leads to a host of indoor air quality (IAQ) and HVAC operational problems. UVC also destroys airborne viruses and bacteria that circulate through an HVAC system.

For the most effective microbial control, Steril-Aire UV germicidal emitters are installed on the supply side of the system, downstream from the cooling coil and above the drain pan. This location provides more effective biofilm and microbial control than in-duct UVC installations.  By irradiating contaminants at the source – the cooling coils and drains pans – Steril-Aire UVC removes surface microorganisms and destroys airborne microorganisms simultaneously. Steril-Aire patented this installation configuration in 1998.

The recirculating air in HVAC systems creates redundancy in exposing microorganisms to UVC, ensuring multiple passes so the light energy is effective against large quantities of airborne microorganisms.  Steril-Aire UVC delivers the highest UVC output, driving HVAC system efficiency while improving indoor air quality.

UVC use in HVAC systems is now recognized as an important contributor to improved indoor air quality, biofilm control, energy savings, and maintenance reductions in commercial, residential, health care and other environments. According to a report issued June 24, 2009 by ASHRAE, airborne transmission of diseases through heating and air conditioning systems may be much more common than previously thought. ASHRAE cites UVC as one of the control strategies that may help avoid transmission.

ASHRAE Position Document on Airborne Infectious Diseases

The EPA Report

The most comprehensive independent source of information for comparing UVC lamp systems is a series of 2006 test reports titled “Biological Inactivation Efficiency of HVAC In-Duct Ultraviolet Light Devices”. This testing was commissioned by the Environmental Protection Agency (EPA) in conjunction with the National Homeland Security Research Center (NHSRC) and conducted by RTI International. This test confirms that, on average, Steril-Aire UVC Emitters are 6 times more effective than tested competitor’s UV on a kill/watt basis.

The research reports can be accessed on the EPA website:http://cfpub.epa.gov/si/si_public_record_report.cfm?address=nhsrc/si/&dirEntryId=233212

Steril-Aire’s multi-patented UVC Emitters deliver the longest-lasting UVC performance available.  As shown in the comparison graph below, it has been independently tested and proven to deliver up to 6 times the output of other UVC devices under HVAC operating conditions.

BEHIND the SCIENCE of UVC LIGHT

CASE STUDIES

Levels of fungi growing on insulation within air-handling units (AHUs) in an office building and levels of

airborne fungi within AHUs were measured before the use of germicidal UV light and again after 4 months of

operation. The fungal levels following UV operation were significantly lower than the levels in control AHUs.

Links

HVAC systems have been shown to collect, amplify and spread microorganisms such as Aspergillus, Pseudomonas, Enterobacter and Acinetobacter that cause health-care-associated infections (HAIs) and increase patient morbidity and mortality. Implementing germicidal ultraviolet light in HVAC systems at the AC coil can eliminate these microorganisms and reduce health-care-associated infections, leading to significant reduction of non-reimbursable hospital charges.

The science behind Steril-Aire UVC emitters.

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The science behind Steril-Aire UVC emitters.

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Click Here for EPA Study