Issue link: https://hi.iaq.net/i/866954
bacteria were killed. The kill rate increased with increased voltage or with the first applied field strength (applied voltage divided by the distance of the ionizer wires from the control ground electrode), V/d1. At field strength (V/d1) of 4.2kV/cm, there was no growth after 24 hours of incubation. After 48 hours, there was either no growth or small (in size and in number) colonies grown. These small colonies were identified as S. epidermidis, and were identical in biochemical profile as the isolate used in the tests. It was concluded that four hour sat 4.2 kV/cm (V/d1) did not completely kill the S.epidermidis. If the bacteria were not all killed, some of them were damaged sufficiently so that no growth or very limited growth could occur after 24 hours incubation. When the ionizing time was increased to seven hours, over 99% of the bacteria (as compared to the control) were killed. When the applied field strength, V/d1, was increased to 4.5 kV/cm or higher, no growth occurred on any of the filter pieces except for one experiment. This exception may have occurred because the starting dose of bacteria for this experiment was three times higher than for the control and up to 10 times higher than for any other experiment. Nonetheless, there were still three to four logs of killing using an applied field strength, V/d1 of 4.5 kV/cm or higher, as compared to the control experiments. It should be noted that, in practice, bacteria caught on the filter are held within the ionizing field for an almost infinite amount of time, thus receiving an almost infinite radiation dosage. Hence, in practice, the killing efficiency should be higher even at lower field strengths. Similar results were obtained using E. coli in a previous study conducted with the DFS "AKA" EEF at the University of Wisconsin. IV. Field Results in Cleanrooms For summary of above described research & field results please see link below http://www.ivtnetwork.com/sites/default/files/Cleaning-Validation-Volume-III.pdf V. Efficiency and MERV Rating The Efficiency of the DFS system is reported to be 99.999% @ 0.007 µm in comparison to HEAP standards 99.97 @ 0.3 µm. Additional ASHRAE Standard 52.2-2012 Filter testing and EN-1822-5 test ( Efficiency / MPPS / Resistance) of the commercial 2000 SC DFS at air flow rate of 2000 CFM showed the filter exceeds the MERV 16 class. VI. UVGI Process Description A UV disinfection system transfers electromagnetic energy from a mercury arc lamp to an organism's genetic material (DNA and RNA). When UV radiation penetrates the cell wall of an organism, it destroys the cell's ability to reproduce. The effectiveness of a UV disinfection system depends on the characteristics of the airborne microorganism, the intensity of UV radiation, the time the microorganisms are exposed to the radiation, and the reactor configuration. For any one air filtration system design, disinfection success is directly related to the concentration of colloidal and particulate constituents in the air stream.