Labconco FilterMatPortable Exhausters 3970024 - Manual (Page 27)

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Chapter 4: Using Your FilterMate
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TWA - Recommended Exposure Limits expressed as a Time
Weighted Average. The exposure limit for that chemical for up to
a 10-hour workday, 40 hours a week.
Odor Threshold - The value in parts per million for which one
might expect to smell a chemical’s presence in the air. This value
is very subjective and detection will vary with the sensitivity of
one’s nose. The period of time until the odor threshold is reached
in the exhaust stream can be estimated from Labconco’s exclusive
computerized filter modeling program. Contact Labconco on
carbon filter life for specific applications.
Saturation Level or Time - There is a limit to the amount of
chemical that can be adsorbed by activated carbon, or neutralized
by chemically treated carbon. Once the capacity of the carbon is
reached, it is considered to be saturated and will adsorb (or
neutralize) no further material; the outlet concentration of the
chemical will equal the inlet concentration from that point until the
filter is replaced. (Note that the capacity of activated carbon is not
a constant, but varies with the inlet concentration). Labconco
Technical specialists can determine with the computerized carbon-
modeling program the estimated time to saturation for a particular
chemical. When using a HEPA filter alone or in combination with
a carbon filter the speed control will need to be increased to allow
for HEPA filter loading. Measure enclosure face velocity with an
anemometer.
IDLH (Immediately Dangerous to Life and Health). An
atmosphere that poses an immediate hazard to life or produces
immediate irreversible health effects. IDLH concentrations should
not be approached in the enclosure.
Appropriate Chemicals
Below is a general set of rules to determine appropriateness of
chemical usage.
Selected organic chemicals considered to be
occupational carcinogens by NIOSH can be used
in the FilterMate under rigid restrictions. See
separate discussion on carcinogens for special
instructions.
Organics must have time weighted exposure limits (TWA) of 1
PPM or greater.
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