Thermal conductivity detector

Abstract

A thermal conductivity detector includes: a first flow path (4) in which a filament (2) is arranged; a second flow path (6) provided separately from the first flow path (4); an introduction flow path (8) configured to fluidly communicate between an upstream of the first flow path (4) and an upstream end of the second flow path (6); a sample inlet (10) configured to introduce a sample gas to the introduction flow path (8); a first gas inlet (12) provided between the sample inlet (10) in the introduction flow path (8) and an upstream end of the first flow path (4); a second gas inlet (14) provided between the sample inlet (10) in the introduction flow path (8) and an upstream end of the second flow path (6); a carrier gas supply source (18); a selector (22) configured to selectively introduce the carrier gas from the carrier gas supply source (18) to one of the first gas inlet (12) and the second gas inlet (14); and a detection circuit (24) configured to detect a component in a sample gas via the filament (2), wherein when the carrier gas from the carrier gas supply source (18) is guided to the first gas inlet (12), a reference phase in which only the carrier gas flows through the first flow path (4) is formed, when the carrier gas from the carrier gas supply source (18) is guided to the second gas inlet (14), a sampling phase in which the sample gas flows through the first flow path (4) is formed, and wherein fluid resistance of the first flow path (4) and flow resistance of the second flow path (6) are designed such that a ratio of a difference between a reference flow rate and a sampling flow rate to each of the reference flow rate and the sampling flow rate becomes 15% or less, the reference flow rate being a flow rate of a gas flowing through the first flow path (4) in the reference phase, the sampling flow rate being a flow rate of gases flowing through the first flow path (4) in the sampling phase.

Dependencies are inferred from the claim text.