Thermocouples Calibrations Services

The Thermocouple Calibration Laboratory calibrates thermocouples of the following type:

• Base Metal
  • letter designated (E, J, K, N, T)
  • non-letter designated (W/Re, Ir/Rh, Pt/Rh), as a special test
• Noble Metal (S, R, B)
• Pure Metal (Au/Pt)

Calibration services for all commonly used types of thermocouples are provided by NIST from -196 °C to +2100 °C. The temperature range for a particular calibration depends on the type of wire or thermocouple submitted.

Thermocouples are calibrated by either comparison or fixed point, depending on the type of thermocouple, the temperature range, and the accuracy required. Both methods provide traceability to the International Temperature Scale of 1990 (ITS-90). Comparison calibration of thermocouple wire uses a reference thermocouple maintained at NIST. Fixed-point calibration of thermocouples use four defining temperatures of the ITS-90: the freezing points of zinc, aluminum, silver, and gold.

Single-leg thermoelements are tested against the NIST maintained platinum thermoelectric reference standard, Pt-67, by the first or second method.

Only bare wires are needed for NIST thermocouple calibrations. We would prefer customers not to send ceramic insulating and protecting tubes since they may get broken during shipment. If the thermocouple is shipped in a mount such as a protection tube assembly, a special dismantling fee may be charged and the parts will be returned unassembled.

The minimum length for thermocouple wire submitted for calibration should be at least:

• Comparison Calibration
  • 70 cm for Types E, J, K, N, T, S, R
  • 80 cm for Type B
  • 100 cm for W/Re
• Fixed-point Calibration - 100 cm

For base-metal thermocouples (types E, J, K, N, and T) and thermocouple materials, only those that are unused will be accepted for test. A calibration will be undertaken only if the thermocouple is likely to yield the specified accuracy.

How to Arrange a Calibration

1. Go to Shop NIST web page
2. Down arrow for Calibrations
3. Scroll to Thermodynamic and click
4. Scroll to Thermocouples and click
5. Contact the staff member in charge of the calibration service for your artifact with any technical questions.
6. Calibrations are performed on a first come first serve basis.
7. Use a sturdy box in which we can return the calibrated instrument.

Calibration Measurement Uncertainties

Summary of standard uncertainties u of calibrations of type S and type R thermocouples at the gold, silver, aluminum, and zinc fixed points. Uncertainties are expressed in °C.

Propagated expanded total uncertainty U at temperature t for fixed-point calibrations of type S and type R thermocouples, in units of °C.

Propagated expanded total uncertainty U, in units of °C, at temperature t for fixed-point calibrations of type B thermocouples

Total expanded uncertainty U in units of °C, for calibrations of type R and type S thermocouples by comparison with a type S reference thermocouple, as a function of temperature t. 

Total expanded uncertainty U in units of °C, for calibrations of type B thermocouples by comparison with a type S reference thermocouple, as a function of temperature t.

Total expanded uncertainty U in units of °C, for calibrations of base-metal thermocouples by comparison with a type S reference thermocouple, as a function of temperature t.

Total expanded uncertainty U for calibrations of base-metal thermocouples by comparison with a SPRT reference thermometer in a temperature-controlled bath, as a function of temperature t.