Frequently Asked Questions - Thermocouples

Question

Answer

A thermocouple is a temperature sensor that consists of two different types of metals joined together at one end. When there is a temperature difference between the two ends of the metals, it creates a voltage difference, known as the Seebeck effect. This voltage can be measured and correlated with the temperature difference, allowing the thermocouple to accurately measure temperature.

Question

What are the types of thermocouples, and which one should I choose for my application?

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There are several types of thermocouples categorised by their metal combinations, such as Type K (chromel-alumel), Type J (iron-constantan), Type T (copper-constantan), Type E (chromel-constantan), and Type N (nicrosil-nisil). The choice of thermocouple type depends on factors like temperature range, environmental conditions, accuracy requirements, and chemical compatibility with the measuring environment. For example, Type K thermocouples are widely used due to their broad temperature range and versatility.

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Thermocouples offer several advantages, including fast response times (typically within seconds), wide temperature measurement ranges (-200°C to 2300°C), ruggedness and durability in harsh environments, simplicity of design, cost-effectiveness, and compatibility with various industrial processes. Their ability to withstand extreme temperatures and environments makes them suitable for diverse applications across many industries.

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The accuracy of thermocouples depends on factors such as the type of thermocouple, the temperature range, calibration, junction type (grounded or ungrounded), wire quality, and environmental conditions (e.g., vibration, electromagnetic interference). Generally, thermocouples can provide accuracies within a few degrees Celsius or Fahrenheit, but careful calibration and maintenance are necessary to ensure optimal accuracy over time. View our standard thermocouple accuracy chart here

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Can thermocouples withstand harsh environments, and what are their common applications?

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Thermocouples are designed to withstand harsh environments such as high temperatures, corrosive atmospheres, and mechanical stress. Common applications include temperature monitoring and control in industries like manufacturing (e.g., heat treating, metal processing), HVAC systems, automotive, aerospace, energy generation, food processing, pharmaceuticals, and scientific research laboratories.

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The Harmonised System (HS) tariff code (also known as the commodity code) for a thermocouple when importing or exporting is 90259000.