Labconco Class I Enclosure Models 3980423 - Manual (Page 49)

Chapter 6: Maintaining Your Filtered Enclosure
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Steps for Calculating PPM and Filter Life
1. Determine the amount of the proposed chemical lost to evaporation over a
given amount of time. For example, if you use isopropyl alcohol and lose
approximately 100 ml per week during 2 hours of use per day.
2. Convert the amount lost into ml/min. For this example:
100 ml X 1 week X 10 hours = 100 ml lost
week 10 hours use 600 minutes 600 minutes
3. Convert ml/min to PPM by multiplying ml/min by the conversion factor
found in the second to the last column on the right. For isopropyl alcohol
.17 x 41 = 7.0 PPM.
4. Find the PPM value on the chart that comes closest to the value you just
calculated in step #3. In this example, round up to 10 PPM, which is close
to the calculated 7.0. We may approximate the filter life to be around 155
hours of actual use, but use 50% of this for the Odor Control filters or 78
hours.
5. Insert the estimated filter life into the estimated usage to determine how
long filters will last.
78 hours filter life
10 hours per week use
Formaldehyde only
For formaldehyde, use 10% of the impregnated carbon weight. Formalin is 37%
formaldehyde by weight. The density of formalin is 1.08 g/ml.
Model
Size Filter Size
Pounds of
Formasorb
Carbon
Adsorbed weight of
Formaldehyde
Adsorption
Volume of
Formalin
2' 18 x 18 x 1 7.0 0.7 lbs./318g 796 ml
3' 30 x 18 x 1 12.0 1.2 lbs./545g 1364 ml
4' 42 x 18 x 1 16.8 1.68 lbs./763g 1910 ml
Ammonia only
For ammonia, use 10% of the impregnated carbon weight. Assume use of a 50%
solution of ammonia for these calculations.
Model
Size Filter Size
Pounds of
Ammonasorb
II Carbon Adsorbed weight of
Ammonia
Adsorbed
Volume of 50%
Ammonia
Solution
2' 18 x 18 x 1 9.2 0.92 lbs./418g 836 ml
3' 30 x 18 x 1 13.5 1.35 lbs./613g 1226 ml
4' 42 x 18 x 1 18.9 1.89 lbs./859g 1718 ml
=7.8 weeks before filter saturation
=.17 ml/min