permeation tube
A device used for dynamic preparation of test gas mixtures by means of controlled permeation of a gaseous analyte out of a container through polymer material into a @C00863@ stream. These devices containing certain condensable gases (e.g. NO2 , SO2 , etc.) when operated at closely controlled temperatures can be used as primary standards calibrated in terms of the @W06668@ loss per unit time.
PAC, 1990, 62, 2167. (Glossary of atmospheric chemistry terms (Recommendations 1990)) on page 2205 [Terms] [Paper]