Heat conduction gas sensor

It can detect various gases.It is used in utility tunnels, gas pipes, incubators, etc.

As shown in the figure, the basic structure of the heat conduction gas sensor is to weld a platinum wire coil between two electrode pins and form detection and compensation elements in the coil part in the center of the platinum wire.Stainless steel wire mesh has a structure with explosion-proof performance, and there are sintered metal types in addition to metal mesh, which are selected according to the application.A heat-resistant insulator is used for the mount base.The difference from the contact combustion type gas sensor is that the compensating element is covered with a stainless cap and has a sealed structure that does not come into contact with the gas to be detected at all.

The detection principle of a heat-conducting gas sensor is almost the same as that of a contact combustion gas sensor, but the decisive difference is that the heat-conducting gas sensor senses using the heat conductivity peculiar to the gas, not the combustion of the gas.Specifically, when the gas comes into contact with the detection element, the state of heat dissipation changes due to the thermal conductivity peculiar to the gas, and the element temperature changes.The compensating element is housed in a sealed housing, and the temperature does not change due to gas.The temperature change of the detection element is regarded as the resistance value, and the difference in resistance value from the compensation element is detected by the Wheatstone bridge circuit.