The disclosure includes a gas chromatograph for underground use comprising a fixing board. In some embodiments, the gas chromatograph for underground use includes a power connection socket, at least one three-way solenoid valve, a quantitative loop, an analysis module, a communication main board, a data transmission device, a sample injection membrane valve, and a gas injection pump detachably coupled to the fixing board. In some embodiments, the quantitative loop and the sample injection membrane valve are arranged and configured to couple to at least one of the at least one three-way solenoid valves.

A thermal conductivity sensing device (1) is disclosed, along with a method for operation of the thermal conductivity sensing device and use of the thermal conductivity sensing device in a system for gas chromatography and a method of carrying out gas chromatography. The thermal conductivity sensing device is for use in sensing one or more gaseous components in a flowing gaseous environment. The device has a first sensor (4B) and a second sensor (4A) for exposure to the same flowing gaseous environment (G). The first sensor has an associated flow altering means (20) to affect gas flow at least at part of the surface of the first sensor, to be different to gas flow at the surface of the second sensor. Each sensor provides an output relating to heat transfer between a surface of the sensor and the gaseous environment. The device is operable to compare outputs of the first and second sensors. The sensor is able to reduce the effects of bulk convection of the flowing gas on thermal conductivity measurements.

A thermal conductivity sensing device (1) is disclosed, along with a method for operation of the thermal conductivity sensing device and use of the thermal conductivity sensing device in a system for gas chromatography and a method of carrying out gas chromatography. The thermal conductivity sensing device is for use in sensing one or more gaseous components in a flowing gaseous environment. The device has a first sensor (4B) and a second sensor (4A) for exposure to the same flowing gaseous environment (G). The first sensor has an associated flow altering means (20) to affect gas flow at least at part of the surface of the first sensor, to be different to gas flow at the surface of the second sensor. Each sensor provides an output relating to heat transfer between a surface of the sensor and the gaseous environment. The device is operable to compare outputs of the first and second sensors. The sensor is able to reduce the effects of bulk convection of the flowing gas on thermal conductivity measurements.

A gas chromatograph is provided which is capable of effectively reducing the amount consumed of a carrier gas, reducing the time and effort required for an operator to manually set parameters, and preventing damages to a column and a detector due to a setting mistake. In a case where a stop operation for the power supply of the gas chromatograph is performed (Yes in step S101), the flow rate of a carrier gas to be supplied to a sample vaporization chamber is decreased and the temperatures of the column and the detector are sufficiently lowered (steps S102 to S104), and then the power supply of the gas chromatograph is switched over from an ON state to an OFF state (step S106).

A heat flux sensor comprising at least one support, where at least one membrane is suspended relative to the support by at least four nanowires, where the membrane is made from at least one current-conducting material, and where the nanowires are made from a current-conducting material, with two nanowires connected to a current source to polarize the membrane between two terminals and a heater for heating the membrane, and where two nanowires are connected to a voltmeter to form measure the voltage at the terminals of the membrane.

A heat flux sensor comprising at least one support, where at least one membrane is suspended relative to the support by at least four nanowires, where the membrane is made from at least one current-conducting material, and where the nanowires are made from a current-conducting material, with two nanowires connected to a current source to polarize the membrane between two terminals and a heater for heating the membrane, and where two nanowires are connected to a voltmeter to form measure the voltage at the terminals of the membrane.

Provided is a thermal conductivity detector including a detection channel through which a gas to be measured flows as a fluid, a heat conducting part that includes at least a filament provided at a position in the detection channel at which the filament is in direct contact with the fluid flowing through the detection channel, the filament being folded at least once in a direction substantially parallel to a flow direction of the fluid flowing through the detection channel, and that conducts heat via the fluid flowing through the detection channel, and a detection circuit that detects an electric signal in accordance with a change in current or voltage of the filament. The filament is folded by being holed on a folding pin provided substantially perpendicular to the flow direction in the detection channel, and the folding pin has a position shift prevention structure for preventing a fold of the filament hooked on the folding pin from shifting in a longitudinal direction of the folding pin.

Provided is a thermal conductivity detector including a detection channel through which a gas to be measured flows as a fluid, a heat conducting part that includes at least a filament provided at a position in the detection channel at which the filament is in direct contact with the fluid flowing through the detection channel, the filament being folded at least once in a direction substantially parallel to a flow direction of the fluid flowing through the detection channel, and that conducts heat via the fluid flowing through the detection channel, and a detection circuit that detects an electric signal in accordance with a change in current or voltage of the filament. The filament is folded by being holed on a folding pin provided substantially perpendicular to the flow direction in the detection channel, and the folding pin has a position shift prevention structure for preventing a fold of the filament hooked on the folding pin from shifting in a longitudinal direction of the folding pin.

An upstream portion of a flow path is stored in a cell block. A filament for detecting thermal conductivity of a sample gas is stored in the upstream portion. The sample gas is led to a downstream portion of an exhaust pipe path through the flow path. The flow path is kept warm by a temperature retainer such that the temperature of the sample gas that passes through the exhaust pipe path does not decrease to a temperature equal to or lower than a liquefaction temperature of the sample gas. Alternatively, at least one portion including a downstream end of the exhaust pipe path is provided to be attachable to and detachable from another portion of the flow path.

An upstream portion of a flow path is stored in a cell block. A filament for detecting thermal conductivity of a sample gas is stored in the upstream portion. The sample gas is led to a downstream portion of an exhaust pipe path through the flow path. The flow path is kept warm by a temperature retainer such that the temperature of the sample gas that passes through the exhaust pipe path does not decrease to a temperature equal to or lower than a liquefaction temperature of the sample gas. Alternatively, at least one portion including a downstream end of the exhaust pipe path is provided to be attachable to and detachable from another portion of the flow path.