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Chapter 6: Maintaining Your Filtered Enclosure
syringe represents a 100-ml sample and corresponds to the number
of strokes necessary to give the indicated color changes. Due to the
wide variety of organics and varying TWA’s, it is recommended
that specific detector tubes be purchased directly from Sensidyne,
Draeger or your laboratory supply dealer. Alternate detector
pumps can also be purchased from your laboratory supply dealers.
The vast majority of detector tubes available start measuring at the
TWA. When a user observes a color change in the tube, they
should replace the filter immediately. If no detector tube for your
specific chemical is available, other means of detection must be
used.
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.