Importance

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Abstract

A gas chromatograph with multiple valves is disclosed. An embodiment of the multi-valve gas chromatograph includes multiple valves, multiple thermal conductivity detectors (TCD's), and a manifold. This allows separation and measurement of a gas sample in one compact integrated unit. The unit is particularly desirable because the solenoids associated with the valves are attached directly to the underneath of the manifold, thus eliminating the need for tubing between the solenoids and the valves. Other features may also be present. For example, a leak free multi-valve block may include a first temperature zone heating the valves and detectors and a second temperature zone heating the columns. The leak free feature may be achieved by placement of tightening screws through the center of each valve. Carrier gas insertion areas may be provided in the multi-valve block to improve performance. Improved separation of the temperature zones leading to further gains in performance can be achieved by use of both a thermal insulator and an air gap. Further, the temperature sensors placed in the first temperature zone can be ideally located to minimize measurement error, resulting in yet further performance gains.

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First Claim