NAFA Guide To Air Filtration Fifth Edition Chapter

NAFA Guide To Air Filtration Fifth Edition Chapter 14 Ultraviolet Germicidal Irradiation Photocatalytic Oxidation presented by the National Air Filtration Association

Different Bands of UV

UVGI-Range 200 -280 nm

Installed on upstream side of coils

Typical UVGI Lamp Location

How it Works • DNA of microorganisms absorb UVGI energy • Absorption of UVGI “dose” breaks the DNA strand

Dose on the DNA Chain

k values: Susceptibility of microbes to UV Figure 2. General ranking of suceptibility to UVC inactivation of microorganisms by group.

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 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-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

PCO

Types of PCO Reactors

Types of PCO Reactors

Types of PCO Reactors

Types of PCO Reactors

Summary • PCO is an immerging technology for cleaning the air of volatile organic compounds • Complete PCO reduces contaminants to CO 2 and H 2 O – (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?