Frequently Asked Questions

Here you will find answers to the most frequently asked questions intended to help you understand why PurgenixMatrix™ is the preferred solution for pure air.

When selecting a UVGI system, what are the primary considerations that should be taken into account?
What alternative systems are being deployed in the marketplace?
Can a parallel array be designed to achieve the same dosages as an angled array to effectively deactivate a significant level of airborne pathogens?
Can desired URV levels be achieved with a combination of parallel arrays and arrays aligned with the air flow?

When selecting a UVGI system, what are the primary considerations that should be taken into account?

The following factors should be considered when establishing parameters for a UVGI system:

What is the desired outcome from installing a UVGI system?
What UV energy dose (or URV level) is desired for the area being treated? In determining the desired “dose”, there are general recommendations depending on the necessary designation of the system
How much space is available within the air handling units or the ducts for the UVGI system?

By taking into account the answers to all of the above questions, an effective UVGI system can be designed to meet unique requirements.

What alternative systems are being deployed in the marketplace?

There are three different types of systems being used in the marketplace:

Lamp Array Parallel to the Cooling Coil: The array is structured with a number of UV lamps that are parallel to the cooling coil. The primary purpose and scope of this type of array is to irradiate the cooling coil and remove any organic material growing on and inside the cooling coil. The result is a more efficiently operating HVAC system with lower energy and maintenance costs.
Lamp Array Aligned with the Air Flow: This array is structured with a number of UV lamps that are aligned with the air flow and are typically found in the ducts downstream of the cooling coil. The systems are often specifically designed to provide a high URV level that has a high deactivation rate on airborne pathogens and are commonly found in “bio-terrorism shields”. However, even if placed in the vicinity of the cooling coil, the physics of the UV energy does not result in a sufficient dose being delivered to the cooling coil to deactivate the pathogens on the cooling coil. As a result, while air quality will be enhanced due to the deactivation of airborne pathogens, the energy and maintenance savings resulting from a clean coil are generally not achieved. Additionally, due to the space constraints inside the plenum near the cooling coil, this type of array must also be placed in each duct in which the effect is desired further increasing costs.
Lamp Array Angled to the Cooling Coil: The array is structured with the UV lamps at a 45 degree angle to the cooling coil and is set a measured distance downstream of the cooling coil. The system is designed to take advantage of the overlapping fields of UV energy resulting from the angled arrays and the system can be designed to efficiently reach the industry established URV levels to deactivate airborne pathogens. The angled array is sufficiently close to the cooling coil to deliver a more than prescribed UV energy dose to deactivate any pathogens growing on the cooling coil. As a result of the efficiency of the angled array, all of the objectives are met with one installation – airborne pathogens are deactivated and the cooling coil remains clean.

Can a parallel array be designed to achieve the same dosages as an angled array to effectively deactivate a significant level of airborne pathogens?

If there is sufficient space within the plenum to install back-to-back staggered arrays of parallel lamps that will provide overlapping fields of UV energy (refer to EPA Report 52), then it is possible to reach higher URV levels. However, due to the space limitations in the plenum near the cooling coil, this type of configuration generally cannot be implemented. Also because the back-to-back parallel array does not create overlapping fields of UV energy as efficiently as an angled array, a parallel array will generally require higher UV wattage lamps or a higher number of lamps – which will increase installation costs and annual operation costs.

Can desired URV levels be achieved with a combination of parallel arrays and arrays aligned with the air flow?

If there is sufficient space within the air handling unit plenum and in the ducts, similar results to the angled array can be achieved. However, the number of lamps will have to be greater than the number of lamps used in an angled array and, if placed in the ducts, multiple installations will need to be used to achieve the same result of an angled array.