Labconco Protector 3930000 User Manual page 56

Chapter 6: Maintaining Your Enclosure
Determination of When to Replace
Carbon Filters and How to Replace
Both 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 it is 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 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
52 Product Service 1-800-522-7658