Efficiency Of Bacterial Disinfection By A Duct Mounted UV-Aire Air Purifier By: Kane Environmental Assays Sanitary & Environmental Microbiology Bernard E. Kane, Ph.D. 1706 Canterbury Rd Greenville, NC 27858 Ph. 252.355.6789 Oysterdoctor@aol.
Table of Contents Background ..........................................................................................................................3 Organism.........................................................................................................................3 Testing Structure.............................................................................................................3 Testing Airflow Rate ..............................................................................
Background This product study evaluates the effectiveness of the UV-Aire air purifier in reducing the levels of bacteria with a single pass through a simulated air duct system. This device is designed to irradiate the air as it circulates through the home, so the single pass evaluation is the worst-case scenario use of this device. The air in the home will pass through the heating and air conditioning system many times a day, as the air is circulated throughout the home.
ORGANISM APPLICATOR: An atomizing humidifier spray nozzle mounted at the center of the test duct intake was used to distribute the organism into the air stream. The application flow rate was 0.45 gallons per hour. UV DEVICE: A Field Controls UV-Aire air purifier model UV-18 was mounted onto the center of the side of the test duct 6 feet from the exit end of the chamber. The lamp is a UVC germicidal lamp (non ozone producing) 18 inches long with a UV output rating of 73 µW/cm2 at 1 meter from the lamp.
Testing Procedure The testing was performed in two stages. The first stage operated the test chamber with the lamp off. (See table 1) This developed the control data or the base line bacterial levels for the comparison. The second stage operated the test chamber with the lamp on. (See table 2) Two airflow rates were used to evaluate the lamp effectiveness based on exposure time. Airflow velocities through the ducts of a typical residential heating and cooling system range from 300 to 500 feet per min (fpm).
Table 1: Control Data (testing with lamp off) Airflow Sample Air Sampling Velocity Number Duration (min) fpm 1 2 3 4 5 1 1 1 0.5 0.5 500 500 500 500 500 181 193 208 117 118 Total Corrected Particle counts Total min. = 4 1 2 3 4 5 2 2 2 1 1 1000 1000 1000 1000 1000 Total min. = 8 3 Serratia marcescens Corrected Particle Positive hole count Counts 168 167 169 91 92 Total Corrected Particle counts CFU/FT of air (count/min) 241 263 294 138 140 = 1076 269.00 218 216 220 103 103 = 860 107.
Table 3: UV-18X Test data and results (testing with lamp on) Sample Number Air Sampling Duration (min) Airflow Velocity (fpm) Serratia marcescens Positive hole count Corrected Particle Counts 1 2 3 4 2.5 2.5 2.5 5 1000 1000 1000 1000 21 27 28 48 22 28 29 51 Total Corrected Total min = 12.
Conclusion UV-Aire Model Airflow velocity (fpm) Percent Reduction of Bacteria Percent Survival of Bacteria Log Reductions of Bacteria UV-18 UV-18 UV-18X UV-18X 500 1000 500 1000 93.31 71.99 99.00 90.33 6.69 29.01 0.95 9.67 1.17 0.54 2.02 1.01 The testing showed the UV-Aire lamp yields at least a 90% reduction of the test bacteria with a single airflow pass through a duct system at typical airflow rates.
