Labconco Class I Enclosure Models 3980423 - Manual (Page 48)

Chapter 6: Maintaining Your Filtered Enclosure
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Time - For applications that have very consistent inlet concentrations and
operating time, “Time” can be used to anticipate saturation or TWA levels based
on prior experience. However, this does not replace the need for sampling.
Consult Labconco technical specialist for an estimate of carbon filter life based on
chemical usage. Detector tubes, or analytical instrumentation should always be
used to determine concentrations in the carbon filter. It is recommended that the
carbon filters be checked with detector tubes or other means at intervals of 20% of
the total estimated filter life. The exception to the 20% recommendation is
formaldehyde and any carcinogen or suspected carcinogen. These more hazardous
chemicals must be checked at least every 10% of the total estimated time.
Analytical Instrumentation - This is the most accurate means of measuring
concentrations of any chemical. It is the method of choice when no detector tubes
are available or the tubes are not sensitive enough to measure at the TWA
concentration for the chemical. This method is also to be used to determine
saturation when the chemical concentration is below the measurement range of
detector tubes.
Odor Control Carbon Filter Replacement Procedure – See Figures 4-1 and 4-2
for Carbon Filter Replacement.
1. The carbon filters are replaced by first removing the two screws, which
hold the clips to secure the upper diffuser screen. Remove the screws, clips
and upper diffuser screen.
2. Remove the carbon filter in a careful way to avoid the flow switch and
HEPA filter.
3. Re-install the new carbon filter with the gasket down. Replace the upper
diffuser screen, clips and two screws.
4. The weight of the carbon filter with the gasket down will compress the
gasket.
Calculating Odor Control 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 Odor Control carbon filters for the filtered
enclosures 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).