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UVGI Air Purifiers

Article By MG Cooling Solutions In HVAC - September 5, 2020

UV Treatment in HVAC and Other Industries for SARS and Similar Viruses

Ultra-Violet Germicidal Irradiation

  • IAQ Improvement
  • Germicidal Irradiation
  • Energy Savings
  • Green Building Benefits

Importance of Indoor Air Quality

Indoor air quality (IAQ) is one of many factors that determine building functionality and economics. A building with good IAQ is more desirable place to work, learn and conduct business as it affects building occupants and their ability to conduct their activities and creates positive or negative impressions on them. IAQ directly affects occupant health, comfort and productivity.

Serious health impacts resulting from poor IAQ include –

Legionnaires’ disease, lung cancer from radon exposure, and carbon monoxide (CO) poisoning. More widespread health impacts include increased allergy and asthma from exposure to indoor pollutants,molds and other infectious diseases that are transmitted through the air, and “sick building syndrome” symptoms due to elevated indoor pollutant levels as well as other indoor environmental conditions. These more widespread impacts have the potential to affect large number of building occupants and are associated with significant costs due to health-care expenses, sick leave, and lost productivity.

Contaminants Affecting the Indoor Air

  • CO2
  • CO
  • Toxic Mold
  • Viruses
  • Asbestos
  • Dust Mites
  • Dander
  • Pollen
  • Bacteria
  • Dust
  • Carbon
  • Monoxide
  • Radon
  • Fungi
  • Carbon Dioxide

Each project has special air quality needs and challenges, hence we offer a comprehensive solution that is customizable, scalable, effective and robust. Our advanced technology combines high output UVC germicidal irradiation with a state-of-the-art photo-catalytic oxidation Fresh, Clean, Pure Air Solutions for Industries process that reduces VOCs and odors. PCO combined with gas phase and high efficiency filtration provides a complete solution for clean, pure, odor-free air and a healthier, people-friendly environment.

Ultraviolet photons penetrate the cell wall of micro-organisms and alter their DNA structure such that the micro-organism is unable to reproduce or infect. Vacuum Ultraviolet (UVV)-based processes are used for environmental remediation such as air cleaning, wastewater treatment, and air/water disinfection. When UVV irradiation, photolysis, photo-catalysis, and ozone-assisted oxidation are involved at the same time, it results in the fast degradation of air pollutants because of their strong oxidizing capacity.

Both UVC and UVV wavelengths can work together to destroy biological and chemical contaminants that continually circulate within the building. Depending on the application, UVC, UVV or a combination of both wave lengths are used to achieve the desired results.

Applications of UVGI

  • Air-conditioned Offices and Residential Buildings
  • Hotel Rooms, Restaurants, Sewage Treatment Plants and Kitchen Exhausts
  • Hospitals – OPD, Doctor Chamber, Patient Rooms, Operation Theatres and Laboratories
  • Manufacturing facilities of Foods and Pharmaceutical products
  • Cold Storage and Refrigerated spaces for storing of fruits, flowers and vegetables etc.
  • Industrial Kitchens, Auditoriums, Airports, Cinema Halls and Shopping Malls.

Strategy to Address Infectious Aerosols

ASHRAE recommends UVGI as one strategy to address infectious aerosol disease transmission. Coronaviruses are members of the Corona viridae group and contain a single-stranded, positive-sense RNA genome surrounded by a corona-like helical envelope. Coronaviruses have a size range of 60-140nm, with a mean size of 0.10 microns. Table summarizes the results of studies that have been performed on Coronaviruses under UV exposure, Ultraviolet Solutions.

The Electromagnetic Spectrum

  • UV-A — the most abundant in sunlight; responsible for skin tanning and wrinkles
  • UV-B — primarily responsible for skin reddening and skin cancer; also used for medical treatments
  • UV-C — naturally blocked by the earth’s ozone layer and is the germicidal wavelength

The spectrum of ultraviolet light extends from wavelengths of about 100–400 nm. The subdivisions of most interest include UVC (200–280 nm), and UVV (187 nm). Although all UV wavelengths cause some photochemical effects, wavelengths in the UVC range are particularly damaging to cells because they are absorbed by proteins, RNA, and DNA. The germicidal effectiveness of UVC is illustrated in the figure, where it can be observed that germicidal efficiency reaches a peak at about 260–265 nm. This corresponds to the peak of UV absorption by bacterial DNA.

The sun delivers specific UV wavelengths that destroy and deactivate chemical contaminants that are introduced into the atmosphere. Our UV lamp produces the same UV wavelength the sun produces, UVC (Germicidal 254nm) and UVV (Oxidizing 187nm) are produced using quartz glass.

Ultra-violet (UV) energy kills or inactivates microbes (viral, bacterial and fungal species). UV energy attacks the DNA of a living cell, penetrating the cell membrane, breaking the DNA structure of the micro-organism, inhibiting reproduction. UVC is effective in destroying biological contaminants and odours such as mould, bacteria and viruses. UVGI has been used as a supplement to mechanical ventilation to inactivate airborne infectious agents to protect the health of building occupants. Germicidal efficiency of UV wavelengths, comparing High (or medium) and Low pressure UV lamps with germicidal effectiveness. Low pressure mercury vapour lamps radiate about 95% of their energy at a wavelength of 253.7nm, which is coincidentally so close to the DNA absorption peak (260–265 nm) that it has a high germicidal effectiveness.

UVGI inactivates micro-organisms by damaging the structure of nucleic acids and proteins at the molecular level, making UVGI in HVAC Systems with the specific species indicated in each case. The D value indicates the ultraviolet dose for 90% inactivation. The range of D values is 7-241 J/mt2  the mean of which is 67 J/m2 , should adequately represent the ultraviolet susceptibility of the SARS-CoV-2 virus.

Airborne transmission of infectious agents involves droplets that are expelled by sneezing or coughing or are otherwise distributed into the air. Although the liquid/vapour around the infectious agent evaporates, the residue (or droplet nuclei) may remain in the air for long periods, depending on such factors as particle size, velocity, force of expulsion, particle density, infectivity (i.e., viability of the micro-organism when exposed to the environment and its ability to cause infection when a susceptible host is subsequently exposed), humidity and rate of air flow. Airborne spread of infectious agents is directly relevant to the airborne route, and indirectly to the dropletborne and fomite routes.

The role of air-conditioning and ventilation, in preventing airborne infections has drawn extensive attention since the SARS outbreak. The mechanism of dispersion of airborne Small droplets (<5 µm), called aerosols, are responsible for the short & long-range airborne route, and indirect contact route. Large droplets are responsible for the direct spray route and indirect contact route.

UVGI System for HVAC Ducts for Air Disinfection


Ultraviolet Germicidal Irradiation (UVGI) is an established disinfection technology for both surface and airborne disinfection in HVAC systems. Environmental conditions within an air-duct promote the growth of biological contaminants (viz. mold). This contamination eventually spreads down the ductwork and into the living spaces.

The induct UVGi System is designed to maximize airborne kill of dangerous pathogens such as viruses, bacteria, and mold spores. This duct-mounted UVGI system is designed for intensive airstream UV-C irradiation. The system features multiple UV high-output germicidal UV lamps which sterilize airborne biological contaminates as they pass by. The Induct UVGI system is fully customizable and can be configured to fit a wide variety installation parameter.

The UVC band of light alters the DNA of microbes in a manner that causes mutation, cell death, or destroys their ability to reproduce. Thus, they become inactive and harmless. The desired exposure time for adequate dosage in ductwork typically is a minimum of one second. When there is limited time of exposure due to the velocity of the moving air-stream, more than one UV light unit may be required to achieve adequate exposure time. The primary variables important to the design configuration of a UVGI system.

When the air-stream disinfection is the approach, then having the most amount of UV production possible is the preferred method. This can be achieved by using high output (HO) UV lamps. The average irradiance for a typical air duct application should range from 1,000 to 10,000 μW/cm2 depending on the microbe to be inactivated and operating conditions such as air temperature, air velocity, and humidity.

UVGI System for Air Handling Units (AHU)


UVGI for AHU is recognized for the indoor-air-quality benefits of coil-irradiation installations, which, in addition to microorganisms in coils and drain pans, kill airborne infectious microbes (Virus and Bacterias), lowering the incidence of colds, Flu and Transmission of disease through air.

Advantages of the UVGI System in AHU:

• Eliminates growth of MOLD & MILDEW on cooling coil resulting in:

* Improved heat transfer between chilled water in coils and air.

* Improved air flow through coils.

* Eliminates depositions of dust on coils.

• Eliminates Microbial Load (Bacteria and Virus) passing through Air by deactivating /damaging it’s RNA/DNA.

• Improves Indoor Air Quality (IAQ) upwards of 70%.

• Prevents periodic cleaning of coils, thereby significantly reducing maintenance costs.

• Extends the life of the equipment.

• Low initial set up cost.

• Compatible with new and existing HVAC systems.

Human exposure to UVC light may result in unnoticed eye (cornea) damage and skin (sunburn) damage. While these effects are mostly temporary, they can still be very painful.

Most materials, including glass and plastic, attenuate UVC radiation. Maintenance personnel should wear protective clothing, eye wear, and gloves when dealing with lamp replacement tasks to protect against broken lamps and accidental UV exposure.

Additional UVC Safety Considerations:

• Dispose of used lamps in accordance with regulations regarding mercury content.

• Air ducts should be fully enclosed to prevent UV leakage.

• All access doors and panels should have warning labels posted on the outside.

• Interlocks should be installed such that opening any door to a UV lamp chamber will turn off the lamps.

• The UV lamp chamber should have a viewport large enough for the UV state to be viewed from a distance outside the chamber Specially for AHU application.

• Educate installation and maintenance workers on equipment hazards and safe practices.

MG Cooling Solutions which is well known as HVAC services provider is now standing as one of the renowned names for industrial air cooling solutions. We are tied up with leading air purifier manufacturers in India and providing complete support to our clients.

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