Thermocouple Wire Specifications and Tolerances
| Calibration | Standard Calibration Points ºF 1 |
|---|---|
| SERV-RITE® Thermocouple Wire Standard Calibration Temperatures | |
| E J K N T |
300, 500, 1000, 1600 200, 500, 1000, 1400 300, 500, 1000, 1600, 2000 300, 500, 1000, 1600, 2000 200, 500 |
| SERV-RITE® Extension Wire Standard Calibration Temperatures | |
| BX CX EX JX KX |
212, 400 200, 300, 400, 500 200, 400 200, 400 200, 300, 400 |
| NX RX SX TX |
200, 300, 400 400 400 200, 400 |
| XACTPAK® Calibration Temperatures | |
| B E J K |
1600, 2000, 22002, 27002 300, 500, 1000, 1600 200, 500, 1000, 1500 300, 500, 1000, 1600, 20002, 22002 |
| N R S T |
300, 500, 1000, 1600, 20002, 22002 1000, 1500, 2000, 27002 1000, 1500, 2000, 27002 200, 500 |
1 Calibration not made when temperature exceeds wire insulation rating.
2 These calibration temperatures are checked if the sheath and insulation are rated to this temperature.
Initial Calibration Tolerances for SERV-RITE Wire And Cable Reference Junction 0°C (32°F)
| Calibration Type | Temperature Range | Tolerances 1 (whichever is greater) |
||
|---|---|---|---|---|
| °C | °F | Standard | Special | |
| Thermocouple Wire Type | ||||
| B E J K N R or S T |
870 to 1700 0 to 900 0 to 750 0 to 1250 0 to 1250 0 to 1450 0 to 350 |
1598 to 3092 32 to 1652 32 to 1382 32 to 2282 32 to 2282 32 to 2642 32 to 662 |
±0.5% ±1.7ºC or ±0.5% ±2.2ºC or ±0.75% ±2.2ºC or ±0.75% ±2.2ºC or ±0.75% ±1.5ºC or ±0.25% ±1.0ºC or ±0.75% |
±1.0ºC or ±0.4% ±1.1ºC or ±0.4% ±1.1ºC or ±0.4% ±1.1ºC or ±0.4% ±0.6ºC or ±0.1% ±0.5ºC or ±0.4% |
| Extension Wire Type | ||||
|
EX JX KX NX TX |
0 to 200 0 to 200 0 to 200 0 to 200 0 to 100 |
32 to 392 32 to 392 32 to 392 32 to 392 32 to 212 |
±1.7ºC ±2.2ºC ±2.2ºC ±2.2ºC ±1.0ºC |
±1.0ºC ±1.1ºC ±1.1ºC ±1.1ºC ±0.5ºC |
| Compensating Extension Wire Type | ||||
|
BX 2 CX 3 RX, SX 4 |
0 to 200 0 to 870 0 to 200 |
32 to 392 5 32 to 1600 5 32 to 392 5 |
±3.7ºC ±6.8ºC ±5ºC |
|
| Cryogenic Range Wire Type | ||||
|
E 6 K 6 T 6 |
-200 to 0 -200 to 0 -200 to 0 |
-328 to 32 -328 to 32 -328 to 32 |
±1.7ºC or ±1% ±2.2ºC or ±2% ±1.0ºC or ±1.5% |
7 |
- Where tolerances are given in percent, the percentage applies to the temperature being measured in degrees Celsius. For example, the standard tolerance of Type J over the temperature range 277 to 750ºC is ± 0.75 percent. If the temperature being measured is 538ºC, the tolerance is ± 0.75 percent of 538ºC, or ± 4.0ºC. To determine the tolerance in degrees Fahrenheit, multiply the tolerance in degrees Celsius times 1.8.
- Copper versus copper compensating extension wire, usable to 100ºC (212ºF) with maximum deviations as indicated, but with no significant deviation over 32 to 0 to 50ºC (122ºF) range. Matched proprietary alloy compensating wire is available for use over the range 0 to 200ºC (32 to 392ºF) with tolerances of ±0.033 mV (±3.7ºC5).
- Not an ANSI symbol.
- Copper (+) versus copper nickel alloy (-).
- Due to the non-linearity of the Types B, C R and S temperature-EMF curves, the error introduced into a thermocouple system by the compensating wire will be variable when expressed in degrees. The degree C tolerances given are based on the following measuring junction temperatures:
Type Wire Measuring Junction Temperature
- BX Greater than 1000ºC (1832ºF)
- SX Greater than 870ºC (1598ºF)
- Thermocouples and thermocouple material are normally supplied to meet the tolerances specified in the table for the normal specified range. The same materials, however, may not fall within the cryogenic tolerances in the second section of the table. If materials are required to meet the cryogenic tolerances, the purchase order must so state. Selection of materials usually will be required. Tolerances indicated in this table are not necessarily an indication of the accuracy of temperature measurements in use after initial heating of the materials.
- Little information is available to justify establishing special tolerances for cryogenic temperatures. Limited experience suggests the following tolerances for Types E and T thermocouples:
- Type E -200 to 0ºC ±1.0ºC or ±0.5% (whichever is greater)
- Type T -200 to 0ºC ±0.5ºC or ±0.8% (whichever is greater)