UVC for AHU Commercial

Description

The air handlers must have UVC lamps installed in such a way that the entire surface is illuminated, this guarantees a disinfection greater than log 4 (99.99%) on the surface of the coil. The fundamental objective is to protect the surface of the coil from biofilm. The biofilm formed by fungi, mold and bacteria causes a decrease in air flow and produces inefficiency when it comes to transferring heat. Savings of up to US$ 6,000.00 per year can be calculated for an 80-ton handler just by improving energy efficiency, without taking into account the savings in coil maintenance.

UVC 253.7nm lamps can also be used to disinfect the airflow, in this case the number of lamps is greater. For example, for Sars Cov2 the following rule can be followed.

1.- The length of the coil determines the size of the UVC lamp

2.- The height of the coil determines how many lamps must be installed

Log1 90% disinfection: separation between lamps 40 cm, dose approx 1.2 mJ/cm2

Log2 99% disinfection: separation between lamps 20 cm, dose approx 3.5 mJ/cm2

Log3 99.9% disinfection: lamp separation 10 cm, dose approx 7 mJ/cm2

The exposure time in UMAS varies between 0.1-0.8 seconds. For different viruses or bacteria, the separation distances may vary and the calculation must be made with the Keitz formula (review the guide).

To validate these settings, an in-line dose meter (uW/cm2) can be installed, a single-use mJ/cm2 dosimeter can also be used.