Thermal conductivity detector
AssigneeServeron Corporation
InventorsSteve Mahoney, John Hinshaw
Life of this patent
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Abstract
A thermal conductivity detector (TCD) utilizes a modular thermistor assembly that mounts to the TCD body. The thermistor assembly is easily replaceable in the TCD. Within the TCD, a thermistor bead is always held in the same relative location in a gas flow path, which is designed to produce laminar, low velocity gas flow across the thermistor bead. Two TCDs, each having a heater, are mounted in an insulated enclosure. The heaters are activated to bring the TCDs to operating temperature, and are then deactivated during analysis.
Claims20
A thermal conductivity detector for use with a chromatograph, comprising:
- a body having an axial bore therethrough, said bore defining a chamber having a first diameter and an outlet having a second diameter that is less than the first diameter, wherein the chamber diameter tapers smoothly from the first diameter to the second diameter;
- and said chamber further including an inlet defined by a bore extending through said body substantially transverse to the axial bore;
- said inlet bore, chamber and outlet bore defining a gas flow path through said body;
- a cap affixed to one end of said body and supporting first and second conductors extending through said cap and into said chamber;
- a thermistor bead electrically connected between said first and second conductors in said chamber;
- and
- a heater attached to an outer surface of said body.
A thermal conductivity detector assembly for use with a chromatograph, comprising:
- a first detector having a body having a flow path therethrough, said flow path including an inlet, a chamber and an outlet, said chamber and outlet extending longitudinally along the axis of said body and said inlet defined by a bore extending through said body substantially transverse said axis;
- a chromatographic column fluidly connected to said inlet;
- a cap affixed to one end of said body and supporting first and second electrical conductors extending into said chamber and electrically connecting a thermistor bead in said chamber;
- a heater attached to an outer surface of said body;
- insulation surrounding said body on all sides except one end;
- and said body having one end mounted to a thermally insulated mounting board;
- and
- a second thermal conductivity detector having body having a flow path therethrough, said flow path including an inlet, a chamber and an outlet, said chamber and outlet extending longitudinally along the axis of said body and said inlet defined by a bore extending through said body substantially transverse said axis;
- a chromatographic column fluidly connected to said inlet;
- a cap affixed to one end of said body and supporting first and second electrical conductors extending into said chamber and electrically connecting a thermistor bead in said chamber;
- a heater attached to an outer surface of said body;
- insulation surrounding said body on all sides except one end, and said body mounted to an opposite side of said thermally insulated mounting board.
In a chromatograph using a thermal conductivity detector with a thermistor bead, the method of operation comprising the steps of:
- a) operating the chromatograph in a first operational mode during which the detector is heated and no analysis is being performed, sensing the temperature of the detector during the first operational mode with the thermistor bead;
- and
- b) operating the chromatograph in a second operational mode during which the detector is not heated and analysis is performed with the thermistor bead.
Dependencies are inferred from the claim text.