All Cleveland Electric Labs Thermocouples are built-to-order. From the simplest base metal element to the most complex assembly, we take great care and pride in every product shipped. All of our MgO cable, base metal and noble metal wire is pre-tested to ensure it meets our high standards, and all steps of production comply with our ISO Quality Program. Along with these procedures, our ISO/IEC 17025 Certification Lab performs testing as required to verify the level of accuracy our products provide.
Thermocouple Codes: Conductor Combinations and Characteristics
| ANSI CODE |
CONDUCTOR COMBINATIONS | TEMP. RANGE |
LIMITS OF ERROR | APPLICATION POSITIVE INFORMATION |
||
|---|---|---|---|---|---|---|
| POSITIVE INFORMATION + LEG |
NEGATIVE – LEG |
STANDARD | SPECIAL | |||
| TYPE J | IRON (magnetic) WHITE + |
CONSTANTAN RED – |
32 to 1400ºF (0 to 760ºC) |
±4°F or ±0.75% whichever is greater |
±2°F or ±0.4% whichever is greater |
Suitable for vacuum, reducing, or inert atmospheres. Reduced life in oxidizing atmosphere. Iron oxidizes rapidly above 1000°F (538°C) so only heavy gauge wire is recommended for high temperature. Bare elements should not be exposed to sulfurous atmospheres above 1000°F (538°C). |
| TYPE K | CHROMEL YELLOW + |
ALUMEL (magnetic) RED – |
32 to 2300ºF (0 to 1260ºC) |
±4°F or ±0.75% whichever is greater |
±2°F or ±0.4% whichever is greater |
Recommended for continuous oxidizing or neutral atmospheres. Mostly used above 1000°F (530°C). Subject to failure if exposed to sulfur. Preferential oxidation of chromium in positive leg at certain low oxygen concentrations causes “green rot” and large negative calibration drifts most serious in the1500-1900°F range. |
| TYPE T | COPPER BLUE + |
CONSTANTAN RED – |
32ºF to 700ºF (0 to+370ºC) |
±2ºF or ±0.75% whichever is greater |
±1ºF or ±0.4% whichever is greater |
Useable in oxidizing, reducing, or inert atmospheres, as well as vacuum. Not subject to corrosion in moist atmospheres. |
| TYPE E | CHROMEL PURPLE + |
CONSTANTAN RED – |
32 to 1600ºF (0 to 871ºC) |
±3°F or ±0.5% whichever is greater |
±2°F or ±0.4% whichever is greater |
Recommended for continuously oxidizing or inert atmospheres. Highest thermoelectric output of common calibration. |
| TYPE S
TYPE R |
PLATINUM- 10% Rhodium BLACK PLATINUM- 13% Rhodium + |
PLATINUM RED PLATINUM – |
32 to 2700ºF (0 to 1480ºC) ±2.7°F or ±0.25% w |
±2.7°F or ±0.25% whichever is greater |
±1°F or ±0.1% whichever is greater |
Recommended for high temperature. Must be protected with non-metallic protection tube and ceramic insulators. Continued high temperature usage causes grain growth which can lead to mechanical failure. Negative calibration drift caused by rhodium diffusion to pure leg as well as from rhodium volatilization. |
| TYPE B | PLATINUM- 30% Rhodium GREY + |
PLATINUM 6% Rhodium RED – |
1600 to 3100ºF (871 to 1705ºC) |
±0.5% | ±0.25% | Same as S & R but output is lower. Also less susceptible to grain growth and drift |
| TYPE N | NICROSIL ORANGE + |
NISIL (magnetic) RED – |
32 to 2300ºF (0 to 1260ºC) |
±4°F or ±0.75% whichever is greater |
±2°F or ±0.4% whichever is greater |
Nicrosil/Nisil nickel-based thermocouple alloy used primarily at high temperature (up to 2300°F). While not a direct replacement for Type K, Type N provides better resistance to oxidation at high temperature and longer life in applications where sulfur is present. |
| TYPE C | TUNGSTEN 5% Rhenium GREEN + |
TUNGSTEN 26% Rhenium RED – |
32 to 4200ºF (0 to 2330ºC) |
±8°F or ±1.0% whichever is greater N |
Not Available | This refractory metal thermocouple may be used at temperatures up to 4200°F (2315°C). As it has no oxidation resistance its use is restricted to vacuum, hydrogen or inert atmospheres. |
** Special tolerances for temperatures below 32ºf are difficult to validate due to limited available information. The following values for Types E and T thermocouples are suggested as a guideline for discussion between the customer and Cleveland Electric Labs.
Tolerance values for Type J thermocouples at temperatures below 32ºf and special tolerances for Type K thermocouples below 32ºF are not given due to the nature of the material
Type E -320 to 32ºF ± 2ºF or ±0.5% (whichever is greater)
Type T -320 to 32ºF ± 1ºF or ±0.8% (whichever is greater)
