What’s The Difference Between Ultraviolet Light, Coil Cleaning, and Induct Air Disinfection?

A lot of Engineers, consultants, facility managers, building owners and HVAC contractors walk past an air handling unit and see the blue light shining through the viewport, assume it is doing air disinfection. “INCORRECT” Coil Cleaning UV lamps are installed perpendicular in front of the cooling coil to remove biofilm and mould off the coil. It will not kill viruses, bacteria and fungi in the air passing over the lamp. UV lamps glow blue because of the small amount of mercury in the lamp, reacting with the electrodes when powered up. Just because the UV lamp is glowing blue, it is not an indication the UV lamp, is still producing enough UV energy, to clean the surface of the coil. 

All UV lamps will eventually need replacing because the UV energy will dissipate over time. UVC lamps range from 17000 hours / 2 years to 9000 hours / 1-year life cycle depending on the manufacturer.

Sanuvox UVC lamps last 17,000 hours and need replacing every two years. Opira Group is the sole distributors for Sanuvox in Australia. Sanuvox UV lamp systems come complete with a run hour timer, does the lamps you currently have installed have a run timer to give an indication when the UV lamps need replacing? 

Sanuvox UVC lamps have an aluminium parabolic reflector on the back of the lamp because all the UV energy should be focused on the surface of the cooling coil, and not wasted shinning on all the other surfaces in the air handling unit. There are many coil cleaning UV lamps on today’s market that do not have an aluminium parabolic reflector. This can cause damage to other materials in the air handling unit, powder coating, plastics and wiring if they are not UVC rated. Opira Group uses software to calculate the length and quantity of UV lamps. After 1,700 hours of run time, the lamp will still have 250 mW/cm2 of UV energy to kill even the toughest mould species found on a cooling coil. (Aspergillus Niger) 

The Sanuvox Bio Wall UV inline duct air disinfection system has been used in hospital facilities, education, and commercial high-rise buildings to eliminate viruses, bacteria, and spores worldwide. The UV lamps are installed parallel with the airflow in the supply or return air duct. The BioWall consists of five UVC lamps in a 360-degree configuration. All lamps have an aluminium parabolic reflector on the back, to reflect the UV light onto the walls of the duct. An aluminium lining should be installed around the BioWall inside the duct to increase the UV energy and reflection. The air disinfection system can be used to Kill Covid - 19 and multiple other viruses – Influenza A&B, Tuberculosis, Sars- Cov -2, Coronavirus, E- Coli etc. Depending on the airflow rate l/s and the size of the duct, will determine the lamp length, and how many BioWalls will be required.

Opira Group uses an engineered Sanuvox software to calculate the amount of UV energy, required to kill the viruses, bacteria, and spores on a project. The air in the conditioned space can be disinfected on the first air pass with a three-log kill at 99.9 %. 

For air disinfection to occur in a duct the UV lamps must be installed in parallel with the airflow because to inactivate the DNA cells in viruses, bacteria, and spores, you need to dwell time over the UV lamp. The UV lamps can either be installed in the return or supply air duct. 

Dwell time = UV energy 

 UVC Lamps Parallel and Perpendicular to the Air flow in a Duct

Sanuvox UV coil cleaning and disinfection systems are supplied standard with BMS contacts, indicating when the 17000 hours UV lamp life is expired, and the lamps need replacing or any faults that may occur. The UV lamp size is 19mm and the UV lamp lengths vary from 350mm to 1500mm. The ballast box has a fifteen-year warranty. 

Conclusion: Coil cleaning and air disinfection UV, are two different systems. Be aware of UV lamps on the market that only lasts 9000 hours, and not 17000 hours and do not have an aluminium parabolic reflector. Always use a run timer on UV lamps, to determine when the life cycle running hours have expired. 

Contact Opira now and we can help you choose the correct UV in-duct sterilisation products that will work best with your system. We have experts based in Brisbane, Sydney, Melbourne and Perth. Simply request a quote and we can walk you through all the details.

 - Written by Dean Cooper, June 2021.

Indoor airIndoor air qualityOffice safetyUltra violetUv lightWorkplace safety