Manual

Chapter 6: Maintaining Your Enclosure
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Calculating Carbon Filter Life
Labconco developed a modeling program to estimate the filter life for typical
carbon filters. Since filter life is dependent on the chemical used, the airflow, filter
size, and the dwell time, refer to the Chemical Guide for the Paramount® Filtered
Enclosure. The estimated life for carbon filters for the Protector Work Stations
with integral blower is conservatively calculated at 50% or half of the published
values for the Paramount in the Chemical Guide. For example, if you use
isopropyl alcohol to disinfect and use approximately 100 ml per week during 2
hours of use per day then follow these steps to calculate the concentration in parts
per million (ppm). Important: Two filters are always required for operation. If
mixing filter types, then use 25%.
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 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
6. These values are for two organic vapor filters. If mixing the filters with
formaldehyde or ammonia, then use 25% instead of 50%.
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. These values are
for one filter. If using two filters, then double the adsorption volume.
Number
of
Filters
Filter Size
Pounds of
Formasorb
Carbon
Adsorbed weight of
Formaldehyde
Adsorption
Volume of
Formalin
1
36 x 18 x 1
13.3
1.33 lbs./604g
1512 ml
= 7.8 weeks before filter saturation
=. 17 ml/min