Selection Guide to Wire Calibration

Thermocouples combine dissimilar metals or alloys to produce a voltage. They are classified by calibration types, and each has it’s own unique EMF (electromotive force) vs. temperature curves. An instrument or temperature controller will correlate the voltage to a particular temperature.

Type “J” - Iron vs. Constantan thermocouples can be used from 32°F to 1400°F.* Type J is particularly suited for use in reducing atmospheres. The iron leg tends to oxidize rapidly at temperatures above 1000°F. So large gauge wires inside of protection tubes are recommended at higher temperature.

Type “K” - Chromel vs. Alumel thermocouples can be used from 32°F to 2300°F.* Type K is particularly suited for use in oxidizing atmospheres. It is a reliable and accurate thermocouple and the most commonly used wire calibration type.

Type “T” - Copper vs. Constantan thermocouples can be used from -328°F to 700°F.* Type T can be used in either mildly oxidizing or
reducing atmospheres. It is particularly suited for use at low and cryogenic temperatures.

Type “E” - Chromel vs. Constantan thermocouples can be used from -328°F to 1600°F.* Type E can be used in either mildly oxidizing or reducing atmospheres. It has the highest EMF output of all the common thermocouple types.

Type “R”, “S” and “B” - R & S Platinum-Rodium vs. Platinum thermocouples can be used from 32°F to 2700°F.* Type B Platinum-Rhodium vs. Platinum-Rhodium thermocouples can be used from 1600°F to 3100°F. * Type R, S, & B are used in oxidizing atmospheres and are damaged by reducing atmospheres. These thermocouples are easily contaminated and therefore should be used inside of one or more protection tubes.