Thermocouple Type T: Type T (Copper-Constantan) thermocouples are suited for measurements in the −200 to 350°C (-330 to 660°F) range.
They are often used as a differential measurement as only copper wire touches the probes. Since both conductors are non-magnetic, there is no Curie point and therefore no abrupt change in characteristics. Type T offers the best accuracy of common thermocouples and is often used for food monitoring and environmental applications.
This thermocouple can be used in either oxidizing or reducing atmospheres, although for longer life a protecting tube is recommended. Because of its stability at lower temperatures, this is a superior thermocouple for a wide variety of applications in low and cryogenic temperatures. The recommended operating range is -200 to 350°C (-330 to 660°F), but it can be used to -269°C (-452°F) (boiling helium).
Type T sensors are commonly used for moist or sub-zero temperature monitoring applications. Their superior corrosion resistance and greater homogeneity of the component wires reduces errors due to temperature gradients. Additionally, the non-magnetic properties make the type T a popular choice for sensing in strong magnetic field environments.
As with all thermocouples, there are some disadvantages. Thermocouples need to be calibrated carefully before usage; their output signals are very small and they may have a problem with noise. They are prone to stress, strain, and corrosion, particularly as they age.
The major limitation of the type T thermocouple is with the temperature range—oxidation of the copper limits the usable temperature of Type T to about 370°C (700°F).
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