BT CGA-411 Operation Manual page 22

Dust Filter for Gooseneck Probe
A dust filter in the tip of the gooseneck probe can be cleaned by removing the probe from
the detector and tapping the probe's tip on a hard surface to remove dry dust and dirt. The dust
filter can be popped off the end of the probe and replaced. Replacement dust filters are available
as Part No. DF-005 (package of 5 filters).
Flue Gas Filter
This filter is designed to be screwed finger-tight between the telescoping metal probe and
the water-block filter. It must be used for CO measurements in flue gas and may also be used for
CO measurements in ambient air. The beads in the filter cartridge should be replaced when
about 90% of the material has changed color from purple to brown or when it becomes blocked
by soot or water. Filter beads for refilling approximately 50 cartridges are available as Part No.
PR-050. Replacement flue gas filters are available as Part No. FF-005 (package of 5 filters).
To refill the filter cartridge, remove threaded top and pour out spent filter material.
Retrieve the plastic retainer disk from the spent filter material. Fill cartridge with fresh filter
material to bottom of threads and place the plastic retainer disk flat on top of the filter material.
Screw in top until finger tight and check seal with block test.
WARNING: Do not remove or puncture the white filter in the bottom of the filter
cartridge. If this filter becomes damaged, discard the filter cartridge.
Heavy Hydrocarbon Filter
A heavy hydrocarbon filter, filled with activated carbon, is designed to be used with the
standard probe or the bar hole probe on a one-time-only basis. Activated carbon adsorbs gasoline
and other heavy hydrocarbons (for example, propane or butane) which interfere with methane
detection. In order to keep the filter material from adsorbing hydrocarbons prior to use, the filter
is fitted with plastic endcaps which must be removed just before use. The filter should be either
discarded after use or refilled with activated carbon and recapped with the plastic endcaps. This
filter is designed to be screwed finger-tight between the probe and the water-block filter.
Activated carbon for refilling approximately 50 cartridges is available as Part No. HR-050. The
refill procedure is the same as described for the gas filter. Heavy hydrocarbon filters are
available as Part No. HF-005 (package of 5 filters).
Fig. 5. Dust filter for gooseneck probe.
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