A thermocouple is a sensor for measuring temperature. It consists of two dissimilar metals, joined together at one end. When the junction of the two metals is heated a voltage is produced that can be converted back to the temperature using a pyrometer or electronic controller.
What are the different thermocouple types?
A thermocouple is available in different combinations of metals or calibrations. The most common types used in kilns are K, N and R.
How do I know what thermocouple type to choose?
Type K Thermocouple (Nickel-Chromium / Nickel-Alumel):
The type K is the most common type of thermocouple.
It’s inexpensive, accurate, reliable, and has a wide temperature range.
Type K thermocouples generally have yellow leads with a yellow (+) and a red (-) wire.
Type N Thermocouple (Nicrosil / Nisil):
The Type N shares similar accuracy and temperature limits as the Type K.
Type N thermocouples generally have orange leads with a orange (+) and a red (-) wire
Recommended temperature Range K & N types: –270 to 1260C
When using K & N types a ceramic sheath is suggested to prolong thermocouple life and stop metal scale from falling off into your kiln if firing to stoneware a sheath is required.
Type R Thermocouple (Platinum Rhodium -13% / Platinum):
The Type R is used in very high temperature applications.
It has a higher percentage of Rhodium than the Type S, which makes it more expensive.
The Type R is very similar to the Type S in terms of performance.
Type R has a slightly higher output and improved stability over the type S.
Type R thermocouples generally have green leads with a black (+) and a red (-)wire
Type R are recommended if regular firing to stoneware temperatures.
Type R will last significantly longer than a K or N.
They come with a sheath as part of the thermocouple assembly.
Recommended temperature range Type R: -50 to 1480C
How do I know the correct length for my Kiln?
The thermocouple on a electric kiln requires the metal tip to be around 5cm inside the chamber.
On a gas kiln 10 to 15 cm is recommended.