UVGI Dosage Calculation for 50,000 cfm UV ducted units

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". Calculations are quite a complex integration, however, the basic value can be estimated to be:

Resident Time = CFM/area/lamp length/60 seconds per minute.
= * 50,000*/48.0 sq.ft. = 1040 fpm/60 = 17 feet per second
= 10+ feet/17 feet per second = 0.56+ seconds
Lamp Intensity

= 170 microwatts/cm squared at 1 meter (mfg data)

intensity multiplier at 9" = 39.37"/9" = 4.37 squared
(from N.A. Philips Lighting Handbook)

= 4.37 x 4.37 x 170 microwatts/cm squared at 9"
= 3,246 microwatts per cm squared

Reflection of light at cabinet surface = 1 increase in intensity
Total Efficacy = 0.56+ seconds x 3,246 x 1 x 36 lamps
= 65,440+ microwatt-seconds/cm squared

Lamps are rated at 9000 hour life or 1 year.