Gentek 3980202, 3980423, 3980422, 3980200, 3980401, 3980403, 3980323, 3980400 Definition of Terms

Chapter 5: Using Your Filtered Enclosure and Appropriate Application

THOSE USED AS GUIDELINES FOR THIS

PRODUCT. IT IS THE USER’S

RESPONSIBILITY TO BECOME AWARE OF

LOCAL REGULATIONS GOVERNING THE

SAFE USE AND DISPOSAL OF CHEMICALS,

CARBON AND HEPA FILTERS. KNOWLEDGE

OF ESTABLISHED SAFE EXPOSURE LEVELS

IS IMPERATIVE TO THE PROPER USE OF

FILTERED ENCLOSURES.

Definition of Terms

NIOSH – National Institute for Occupational Safety and

Health/Mine Safety and Health Administration. (U.S.A.)

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. Expressed in units of parts per million or milligrams per cubic meter.

Odor Threshold – The value in parts per million or milligrams per cubic meter 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 exclusive computerized filter modeling program. Contact Labconco on carbon filter life for specific applications. See Chapter 6.

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 saturation for a particular chemical. When using a HEPA filter alone in all filtered enclosures or in combination with an Odor Control carbon filter, the speed control will need to be increased to allow for HEPA filter loading. Measure filtered enclosure face velocity with an anemometer.

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