Thermocouples—the Least Expensive Way to Measure Temperature

Thermocouples are electrical temperature measurement devices designed to gauge the thermoelectric effect resulting from a change in temperature for industrial equipment.

Turbomachinery equipment for power generation and other industrial processes depends on thermocouples as an essential temperature measurement device. By converting heat into a measurable thermoelectric signal, thermocouples can effectively communicate a change in temperature and thus trigger a process control action.

Thermocouples use a select number of alloys—namely chromel, constantan, alumel, and platinum. The type of alloy required for measuring temperature is driven by the purpose and usage of the thermocouple in an industrial environment. In addition, thermocouples must be insulated to ensure chemical resistance—a common challenge in industrial equipment.

Any instance of corrosion due to this chemical resistance can damage the thermocouple and produce faulty readings or degradation that can render the device ineffective.

Determining the thermocouple configuration is dependent on the temperature range, environment, protection, insulation requirements, response and service life. After all, thermocouples provide the least expensive method of sensing temperature but requires understanding its application to ensure the proper use of an alloy.

Thermal energy is measured by using a thermocouple circuitry with two dissimilar metal wires joined at both ends. If the two ends are at different temperatures, the thermocouple can measure voltage that can be translated into feedback that can define a specific temperature.

The range and accuracy of temperature measurements depend upon the conductor materials employed. Pairs of various metal alloys will react differently with changes in temperature.

Most thermocouple installations comprise a thermocouple, extension wires, and an instrument that produces a reading on an indicator. Thermocouple extension wires can be used to connect a thermocouples to instruments at a lower cost and/or to provide improvement in the thermoelectric circuit.

There is much more to thermocouples than we can cover in this article. Therefore, we invite you to contact Temp-Pro today to speak with a knowledgeable member of our team who can help you select the optimal thermocouple configuration.

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