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Learn about Ultraviolet Germicidal Irradiation & Photocatalytic Oxidation in HVAC systems by the National Air Filtration Association. Discover how these technologies work, their benefits, and potential hazards.
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NAFA Guide To Air Filtration Chapter 14 Ultraviolet Germicidal Irradiation Photocatalytic Oxidation presented by the National Air Filtration Association Fifth Edition
How it Works • DNA of microorganisms absorb UVGI energy • Absorption of UVGI “dose” breaks the DNA strand
Figure 2. General ranking of suceptibility to UVC inactivation of microorganisms by group. k values: Susceptibility of microbes to UV
UVGI Can Fill-in the Most Penetrating Particle/Organism Size (MPPS) Gap
UVGI Warning • UV lights have several properties that make them hazardous to human skin and eyes • Skin – Erythema, is a redness of the skin caused by capillary congestion like a sunburn
UVGI Warning • Eyes - Conjunctivitis (commonly called "Pink Eye") is an inflammation (burn) of the conjunctiva which is the the outermost layer of the eye and the inner surface of the eyelids
UVGI Warning - Materials • UVGI can breakdown components in an HVAC system: • Electrical wiring – plastics of all kinds • Filters - synthetic media • Insulation - open-cell foam • Clear plastic – become brittle over time
Summary Just like air filters: • UVGI must be installed correctly • UVGI must be maintained correctly • UVGI combined with air filtration provides an effective two-part particulate removal and microorganism inactivation system
Sample Questions • UVGI is most effective on microorganisms in what range of the light spectrum? 200 to 280 nanometers • Why should UVGI lights be installed downstream of filters? UV light can destroy certain types of filter media material • What should technicians do before servicing units in which UV lights have been installed? Turn off lights prior to opening compartments where lights are located.
Photocatalytic Oxidation (PCO) 254-356 nm
Summary • PCO is an immerging technology for cleaning the air of volatile organic compounds • Complete PCO reduces contaminants to CO2and H2O – (carbon dioxide and water) • PCO adds little pressure drop to the system
Sample Questions • A drawback of PCO may be the? High initial cost of equipment • PCO has how many types of reactor configurations? Four • A PCO advantage is it’s? Reaction at ambient temperatures/ small addition of resistance to the HVAC system/ complete destruction of contaminant into harmless elements
Thank you. Other Questions?