Air Sterilisation – A step to fight COVID-19 in HVAC Industry

Modified Newton Law on humans – human will remain in their state of motion/rest unless a force acts to change them, so now the force acts on us in the form of Corona Virus (COVID-19).

This global pandemic changed the way human use to live, and hence adoption of new technologies is obvious. Various guidelines and researches related to systems which can help in spread of corona virus has been released, and HVAC systems are one of them.

It has been recommended to apply any technology which will limit the spread of this pandemic in air-conditioned space. One of them isimplementation of UVGI(Ultra Violet Germicidal Irradiation) sterilisation in AHU’s/Ducts/occupied spaces.

Based on the researches by various well-known agencies like CDC(Center of Disease Control) USA, NCBI National Center for Biotechnology Information USA,Environmental Protection Agency (EPA) it has been found that UV is effective in limiting spread of COVID-19 andsevere acute respiratory syndrome (SARS) virus that belongs to same family. UVGI is a proven technology which is being used in water disinfection and air disinfection from many years, globally.

As we are trying coming back to normal life/business with safety and precautions, requirement of UVGI increased exponentially and within short span many companies started selling UV tubes as a supplementary business line in addition to their core business and we can hope that they are already aware about the following factors:

• The tubes are certified for its quality or performance
• The proper place and procedure for UVGI installations in air-conditioned space
• The tubes are designed to achieve kill rate required to inactivate Corona virus

More than 90 percent buyers are unaware about the application of UV in their air-conditioned space. Fr every type of air conditioning (Ducted system, cassette units, high walls, FCU’s) different type of UVGI systems are availablei.e upper room UVGI, UVGI for cooling coils, UVGI for duct spaces etc.Users can refer ASHRAE (American Society of Heating Ventilation and Air-Conditioning Engineers) released Position Document on Airborne Infectious diseases.

For the benefit of users, here are some key facts on UVGI system which they can refer and get effective utilisation.
Standard UL-2043 for safety against smoke and fire- Compliant as whole system instead of few parts of UVGI.
ASHRAE Guidelines on UVGI implementation.

Understanding the importance of exposure time vis-à-vis intensity on virus
UVGI on AHU cooling coil is used to eliminate growth of fungus, molds,pathogens and virus on cooling coil not in air flowing through.

For air sterilization duct mount unit with High intensity lamps is recommended as air flow in supply air duct is around 1500 FPM and return duct is 800 FPM approx.hence exposure time of virus with UV light is very less.

ASHRAE wrote a letter to WHO(World Health Organization) on Marc 24th 2020 in context of COVID-19 to offer their expertise and resources to help limit the spread of the disease in buildings, including hospitals and emergency care centers.

ASHRAE also mentioned that while applying UVGI on cooling coils the exposure time of coil and UV source is near to infinity so lamp with low intensity can easily be applied as it will result in low cost and power saving also. Using high intensity UV lamps in AHU may damage some parts like gaskets, sealants, PVC parts, rubber parts etc., as every material has its threshold limit to withstand UV light.

Lot of precautions should be taken while implementingand after installation of UV systems as direct exposure of high intensity UV light is very harmful for human being. Direct exposure may result in skin irritation, eye irritation and long-term exposure may be more hazardous. Best quality and proper wearing of PPE’s while installing and maintaining of such units is must.

This tough time has given the opportunity to both engineers and medical professionals to work together and develop technologies,products to fight such pandemic in future.

These technologies are to save humans from hard-hitting situations like we are facing today, but implementing wrong product/technology may lead to more fatal results, a best product can have accident if not drive/handled properly.

We, at Kleanwave Solutions, strive to serve our nation and mankind with best of our efforts and suitable technologies available at times.

This article is authored by –

Kulwant Singh,
Owner & Entrepreneur,
Kleanwave Solutions