Ultraviolet oxidation: purifying your existing HVAC-system

– by Jaco Heinen – 28/10/20

UV-C purifying systems are excellent safety measures and a powerful weapon against viruses, germs and other micro-organisms. But if used properly, it can only be installed on a newly build system. What about all those vessels that are running on existing HVAC systems? Ultraviolet oxidation might be the solution for you.

Building a conventional UV-C system in your current installation in most cases isn’t possible. You need a lot of space inside your air handling unit which almost all the time simply isn’t available. However, ultraviolet oxidizers can be used in confined spaces and are therefore the alternative upgrade to your existing system.

In this blog you will find out everything you need to know about ultraviolet oxidation.

• How does ultraviolet oxidation work?
• What is the difference between UV-C purifying and UV-C oxidation?
• How to install it on your current system?

How does ultraviolet oxidation work?

Ozone is generated by a UV-C lamp which emits electromagnetic radiation with wavelengths below 200 nanometer. This highly energetic electromagnetic radiation splits oxygen molecules into two separate oxygen atoms, which then attach to each other or to oxygen molecules, forming ozone.

^{Electromagnetic radiation splitting oxygen molecules}

Ozone (O₃) is a molecule composed of three oxygen atoms. A basic oxygen molecule (O₂) is formed out of two oxygen atoms. Oxygen atoms are highly reactive. This means they will easily bound with particles such as bacteria, viruses or other micro-organisms.

The third oxygen atom of an ozone molecule can detach from it, and re-attach to molecules of other substances. The oxidizing process alters their chemical composition and eventually breaks it down.

^{Ozone molecules reacting with micro-organisms}

What is the difference between UV-C purifying and UV-C oxidation?

Although both systems use UV-C light, they are very different ways of filtering. Conventional UV-C light attacks germs and viruses straight on. A virus that is exposed to UV-C light with a wavelength of 265 nanometer will eventually be disabled. The exposure time needs to be long enough. The area of effect is inside the confined space of the air handling unit.

^{Area of effect UV-C purifying system}

An ultraviolet oxidation system indirectly attacks biological agents. The system uses UV-C light with lower wavelengths to generate ozone. These ozone particles attach, attack and disable micro-organisms. The area of effect is not inside the air handling unit, but in the much larger ducting system after the air handling unit.

^{Area of effect ultraviolet oxidation system}

How to install it on your current system?

The big advantage of an ultraviolet oxidizing system is that you can apply it in the limited space of an existing air treatment unit, supply duct or plenum.

Just like oxygen is ozone highly reactive with other organic materials. In high concentrations it can potentially cause harmful health consequences. To reduce the risk of getting ozone in the cabins, the system is equipped with ozone detectors and flow switches. The ultraviolet oxidizer can be connected to the existing switch board for power supply.

Final thoughts

Keep in mind that ozone produced by ozone generators may inhibit the growth of some micro-organisms while it is present, but it is unlikely to fully decontaminate the air unless concentrations are high enough to be a health concern if people are present.

Therefore, see it as an extra safety measure, an upgrade of your HVAC installation that should be used in combination with a solid filtration system.

For more information on ozone generators and the best solution for your HVAC system, contact one of our engineers.

Jaco Heinen | Service & Maintenance Manager

Jaco Heinen has been working at Heinen & Hopman for over eight years. He became the Service & Maintenance manager four years ago and manages the service contracts for maritime HVAC installations worldwide.