UVGI Dosage Calculation for the NQ3000

The calculation of efficacy of the ultra violet lamps is a function of the resident time of the bacteria within sight of the ultra violet light and the intensity of the light within this "Kill Zone".

Resident Time = CFM/area/lamp length/60 seconds per minute.
= 3000/6.0 sq.ft. = 500 fpm/60 = 8 feet per second
= 6 feet/8 feet per second = 0.75 seconds
Lamp Intensity

= 175 microwatts/cm squared at 1 meter (mfg data)

intensity multiplier at 4.2" = 39.37"/4.2" = 9.37 squared
(from N.A. Philips Lighting Handbook)

= 9.37 x 9.37 x 175 microwatts/cm squared at 4.2"
= 15,364 microwatts per cm squared

Reflection of light at 70% at cabinet surface = 1.7 increase in intensity
Total Efficacy = 0.75+ seconds x 15,364 x 1.7 x 4 lamps
= 78,359 microwatt-seconds/cm squared

Lamp cost is $ 32.00 each and life is 9000 hours of continuous operation, which will yield 3 years, if bus use of 6 to 8 hours a day is assumed. Yearly cost is then $ 32.00.