The primary factor in selecting a thermocouple for a given application is the temperature range it will be exposed to. The graph above offers a quick reference for this purpose. Other important factors to consider are the expected lifespan of the element and the process conditions present during operation.

		View our Thermocouple Specifications table

Listed below, in order of increasing maximum temperature limits, are the most commonly used thermocouple calibrations.

ISA Calibration, Element Composition, Recommended Temperature Range, Application Information:

Type T, Copper (+) Constantan (-)
-184° to 371°C, Suitable in oxidizing, reducing, or inert atmospheres as well as vacuum. Moisture resistant and very stable. This type is best suited for low temperature service.

Type J, Iron (+) Constantan (-)
0 to 760°C, Suitable for vacuum, reducing, or inert atmospheres, oxidizing atmospheres with reduced life. As Iron oxidizes rapidly above 530°C, use only heavy gauge wire for high temperatures. Avoid exposing bare wires to sulphurous environments.

Type E, Chromel (+) Constantan (-)
0 to 871°C, Recommended for continuous oxidizing or inert atmospheres. Produces the highest EMF (mV) per degree of all common calibrations.

Type K, Chromel (+) Alumel (-)
0 to 1260°C, Recommended for continuous oxidizing or inert atmospheres. Most common for temperatures above 538°C. Not suitable for sulfur environments. Low oxygen levels can produce ''green rot'', particularly in the 816 - 1038°C range. Use of purge system, inert seal or Type N is recommended for this condition.

Type N, Nicrosil (+) Nisil (-)
0 to 1260°C, Suitable replacement for Type K where oxidization and ''green rot'' are a concern.

Type R, Platinum 13% Rhodium (+) Platinum (-)
538 to 1482°C, Recommended for high temperature applications. Must be protected with non-metallic protection tube. Continued high temperature use can lead to mechanical failure. Most common in industrial applications.

Type S, Platinum 10% Rhodium (+) Platinum (-)
538 to 1482°C, Same as Type R with most common applications in laboratories.

Type B, Platinum 30% Rhodium (+) Platinum (-)
871 to 1705°C, Same as R and S with lower EMF but greater resistance to mechanical failure.

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Non ANSI Coded Thermocouples:
Very high temperature applications in inert or vacuum environments. WR is the most brittle at lower temperatures and W5 the least, due to the Rhenium content in the positive leg.

Type WR, Tungsten (+) Tungsten 26% Rhenium (-)
0 to 2315°C

Type W3, Tungsten 3% Rhenium (+) Tungsten 26% Rhenium (-)
0 to 2315°C

Type W5, Tungsten 5% Rhenium (+) Tungsten 26% Rhenium (-)
0 to 2315°C

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