It is important that each section of wire in a given circuit be homogeneous, since with no change in composition, the circuit EMF depends only on the alloy and the temperature of their junctions. If both junctions are held at the same temperature, the metal does not contribute to the net EMF of the circuit. The law of intermediate metals points out that the introduction of a third metal into the circuit will have no effect upon the EMF generated as long as the junctions of the third metal with the other two alloys are at the same temperature.
In industry today, standard homogeneous alloys are employed for the various calibrations most widely used. These are types K, J, T, and E thermocouples. Others such as R, S, B, N, and W thermocouples are also used for the process and metals industries.
Type Useful Range
T 0
to 350 C +/- .5 C or .4% of
reading
K 0
to 1250 C +/- 1.1 C or .4% of
reading
E 0
to 900 C +/- 1.0 C or .4% of
reading
The calibration used is not as dependant on the output as it was in the past. With the advent of the microchip, electronics can filter out noise and linearized the curve of any type thermocouple with cold junction compensation to 0 C over a broad range to allow one type to be a standard for all measurements. That is why type K thermocouple is the most often specified.
If you don't see what you are looking for here, or if you have additional questions please feel free to contact Temprel at 1-800-582-5098.
If you don't see what you are looking for here, or if you have additional questions please feel free to contact Temprel at 1-800-582-5098.
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