Sampling device for gas analyzers

摘要

A sampling device for a gas analyzer in which a constant-rate flow of diluted sample gas is sampled by a constant-volume sampling device. A gas inlet port of a sampling passage of the constant-volume sampling device is positioned in a throat portion of a main venturi tube, or slightly upstream or downstream of the throat portion. A cold trap is provided downstream of the sampling passage to collect and supply a portion of the sampled gas to be analyzed. The velocity of the diluted sample gas in the throat portion of the main venturi tube is approximately Mach one, so that the sampling thereof is unaffected by pressure or flow-rate changes elsewhere in the system.