Filter
Top Products
56
Chapter 6: Maintaining Your Filtered Enclosure
Determination of When to
Replace Odor Control Carbon
Filters and How to Replace
The carbon filters MUST be replaced when any one of the
following two conditions are met:
1. The filtered enclosure outlet (exhaust) concentration
approaches the inlet concentration, indicating filter saturation.
2. The odor in the work area becomes intolerable or the
concentration of the chemical in the work area is greater than
the TWA.
There are four means of determining when its time to change the
carbon filters (not shown in the order of preference).
Odor - A person’s sensitivity to odor, tolerance of odor and their
comfort level under odoriferous conditions vary with the
individual. While odor is an indicator that chemicals are passing
through the carbon filter, several points need to be understood:
• Odor within the room is not necessarily an indication of
saturation or hazardous exposure concentrations.
• Odor can be used as a prompt to sample the chemical
concentration on the exit side of the carbon filter.
• Organic chemicals approved for use in the filtered enclosure
have odors that are detectable before reaching the time
weighted exposure limits.
Detection Tubes - Color change indicators can be used to measure
the concentration of the chemical at the exit side of the carbon
filter or in the outlet exhaust. A kit including syringe pump and
flexible tubing can be purchased as an accessory from Labconco
(Catalog # 6924900). Labconco Customer Service Representatives
are supplied with detector tube catalog numbers, as well as
telephone numbers to direct you to where to purchase these items.
For Organic, Formaldehyde and Ammonia, chemical specific
detector tubes should be purchased when installing fresh filters.
Each kit contains instructions on how many strokes of the syringe
are required to obtain the stated sensitivity. The sampling syringe
is connected to the filtered enclosure exhaust. Connect the syringe
to the detector tube while the system is running and pull the air
through the tube with the syringe. Each stroke of the