Thermocouple wire types and properties
| Kinds |
Operating temperature limit |
Apply |
| JIS: R |
0～1400（1600）℃ |
(+) leg: Platinum-rhodium alloy containing 13% rhodium
(-) Platinum legs
Good stability. Suitable for oxidizing atmospheres, but weak in reducing atmospheres. Weak against hydrogen and metal gases. |
| JIS: B |
600～1500（1700）℃ |
(+) leg: Platinum-rhodium alloy containing 30% rhodium
(-) Platinum-rhodium alloy containing 6% rhodium
Heat resistance and mechanical strength are better than R. Since the thermoelectromotive force is small at room temperature, copper wire is used for the compensation conductor. |
| JIS: S |
0～1400（1600）℃ |
(+) leg: Platinum-rhodium alloy containing 10% rhodium
(-) Platinum legs
Good stability. Same as R summary. |
| JIS: K |
－200～1000（1200）℃ |
(+) leg Nickel-chromium alloy
(-) Nickel-based alloy
Good linearity of thermoelectromotive force. Suitable for oxidizing atmospheres. Resistant to metal vapor. Weak in reducing atmospheres (especially hydrogen sulfide and sulfurous acid gas). |
| JIS: T |
－200～300（350）℃ |
(+) Copper leg
(-) Legs: Copper-nickel alloy
Good homogeneity. Good precision at low temperatures. |
| JIS: E |
－200～700（800）℃ |
(+) leg Nickel-chromium alloy
(-) Legs: Copper-nickel alloy
Large thermoelectromotive force. More corrosion resistant than J. |
| JIS: J |
0～600（750）℃ |
(+) Leg iron
(-) Legs: Copper-nickel alloy
Suitable for reducing atmospheres (stable against hydrogen and carbon monoxide). Homogeneity is poor. Rusts easily. |
| JIS:N |
0～1200（1250）℃ |
(+) leg Nickel-chromium-silicon alloy
(-) Nickel-silicon alloy legs
The thermoelectromotive force is smaller than that of K. It has excellent stability at high temperatures. |
Tungsten Rhenium
(W95Re5-W74Re26) |
0～2300（3000）℃ |
(+) leg: Tungsten-rhenium alloy containing approximately 5% rhenium
(-) Leg: Tungsten-rhenium alloy containing approximately 26% rhenium
Suitable for high temperature measurement. Cannot be used in oxidizing atmosphere. Suitable for inert gas and hydrogen gas. Relatively large thermoelectromotive force. Hard and difficult to bend. |
Platinel
(Platinel II) |
0～1300℃ |
(+) leg: Platinum-palladium-gold alloy
(-) Palladium-gold alloy
It also has features of a K thermocouple. It is considered to be superior to K at temperatures close to 1300°C. |
Platinum Rhodium 40-20
(Pt60Rh40-Pt80Rh20) |
0～1800℃ |
(+) leg: Platinum-rhodium alloy containing 40% rhodium
(-) Platinum-rhodium alloy containing 20% rhodium
The thermoelectromotive force is smaller than that of B thermocouple. |
Gold-Platinum
(Au-Pt) |
0～1000℃ |
(+) Leg metal
(-) Platinum legs
Used as a standard thermocouple. Wire diameter φ0.5mm. Small electromotive force drift at high temperatures. |
Platinum-Palladium
(Pt-Pd) |
0～1300℃ |
(+) Platinum
(-) Palladium legs
Used as a standard thermocouple. Wire diameter φ0.5mm. Good stability at high temperatures. |
The temperature range in parentheses indicates the overheating limit.
The overheating temperature is the limit of the temperature at which a product can be used for a short period of time when it is unavoidable.
In addition, the DIN standard (Germany) includes two types: U thermocouples (similar to T) and L thermocouples (similar to J).
*Please refer to the catalog for other specifications.
