Thermocouple Manufacture
About the manufacturing of thermocouple
device
Thermocouples are manufactured by
connecting together two wires of different materials, where each
material is produced so as to conform precisely with some defined
composition specification. This ensures that its thermoelectric
behavior accurately follows that for which standard thermocouple
tables apply. The connection between the two wires is effected by
welding, soldering or in some cases just by twisting the wire ends
together. Welding is the most common technique generally used, with
silver soldering being reserved for copper–constantan instruments.
The diameter of wire used to construct thermocouples is usually in the
range between 0.4 mm and 2 mm. The larger diameters are used where
ruggedness and long life are required, although these advantages are
gained at the expense of increasing the measurement time constant. In
the case of noble-metal thermocouples, the use of large-diameter wire
incurs a substantial cost penalty. Some special applications have a
requirement for a very fast response time in the measurement of
temperature, and in such cases wire diameters as small as 0.1 µm (0.1
microns) can be used.
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Temperature Measurements
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