Type K

1. Positive leg is non-magnetic (Yellow), negative leg is magnetic (Red).
2. Traditional base-metal choice for high temperature work.
3. Appropriate for use in oxidizing or inert atmospheres at temperatures up to 1260ºC (2300ºF).
4. Vulnerable to sulfur attack (refrain from exposing to sulfur-containing atmospheres).
5. Perform best in clean oxidizing atmospheres.
6. Not recommended for use under partially oxidizing conditions in vacuum, or when subjected to alternating cycles of oxidization and reduction.

Type J

1. Appropriate for use in vacuum, air, reducing, or oxidizing atmospheres to 760ºC (1400ºF) in the heavier gage sizes.
2. The expected service life of the finer sized wires is limited due to the rapid oxidation of the iron wire at temperatures above 540ºC (1000ºF).
3. Avoid use in sulfurous atmospheres above 540ºC (1000ºF).
4. Limited subzero use due to rusting and embrittlement of the iron conductor.
5. Positive (iron) wire is magnetic (white), negative is non-magnetic (red).

Type E

1. Neither wire is magnetic but negative wire is red, positive is purple.
2. Recommended for use to 900ºC (1600ºF) in oxidizing or inert atmospheres.
3. Appropriate for low temperature to about –230ºC (-380ºF).
4. Has the highest output emf of any standardized type.
5. Vulnerable to sulfur attack, do not expose to this type of atmosphere.
6. Perform best in clean oxidizing atmospheres.
7. Not recommended for use (except in short periods):
   1. Under partially oxidizing conditions.
   2. When subjected to alternating cycles of oxidation and reduction.
   3. In vacuum.

Type T

1. Neither wire magnetic – Positive is blue, negative is red.
2. When used in air:
   1. Moisture resistant.
   2. Very stable.
   3. Useful to 370ºC (700ºF).
3. Higher temperature use possible when used in vacuum, or in reducing or inert atmospheres.
4. Appropriate for use down to –200ºC (370ºF). Special selection may be required of the materials.

Grounded vs. Ungrounded