DAkkS calibration of thermometers at low temperatures
Do you want to calibrate thermometers at extremely low temperatures? But the temperature range of the calibration baths and standardised procedures used is not sufficient for you? Then you’ve come to the right place. We use boiling nitrogen to extend the temperature range.
With the three calibration procedures shown here, you can have thermometers calibrated by us DAkkS in the temperature range from -180 °C to -80 °C and at the fixed temperatures of -189 °C and
-196 °C.
Calibration at low temperatures
Overview of our DAkkS calibration services
Ar
-189 °C
ITS-90 calibration
down to the triple point
of argon
LN2
-196 °C
Thermometer calibration with
liquid nitrogen as reference temperature
-180 °C to -80 °C
Thermometer calibration with
freely selectable calibration points in the nitrogen cryostat
With the boiling nitrogen we can:
Calibrate thermocouples and resistance thermometers with freely selectable calibration temperatures between -180 °C and -80 °C in the DAkkS nitrogen cryostat.
Use the boiling point of nitrogen and calibrate thermometers at -196 °C DAkkS.
put the argon triple point into operation at -189.3442 °C and carry out a complete ITS-90 DAkkS calibration in the temperature range from -189 °C to 0 °C.
The fixed points used are:
Argon triple point -189,3442 °C
Mercury triple point -38,8344 °C
Water triple point 0,01 °C
Accredited calibration according to DIN EN ISO/IEC 17025 (DAkkS) of SPRTs at temperature fixed points (SPRT, Pt 25, Pt 2.5, Pt 0.25)
The accredited calibration according to DIN EN ISO/IEC 17025 (DAkkS) of ITS-90 Standard Platinum Resistance Thermometers (SPRT) is performed at ITS-90 fixed points.
learn more
Accredited calibration according to DIN EN ISO/IEC 17025 (DAkkS) of a Standard Platinum Resistance Thermometer (SPRT) (WGa = 1.11807 or WHg = 0.844235) at the fixed points (freezing points, melting points, and triple points) of the ITS-90. Achievable DAkkS measurement uncertainties, including the ITS-90 deviation function (k=2):
| Temperature Fixed Point | in °C | Measurement Uncertainty |
| Argon Triple Point | -189.3442 °C | 5.5 mK |
| Mercury Triple Point | -38.8344 °C | 3.5 mK |
| Water Triple Point | 0.01 °C | 2.5 mK |
| Gallium Melting Point | 29.7646 °C | 2.5 mK |
| Indium Freezing Point | 156.5985 °C | 5.5 mK |
| Tin Freezing Point | 231.928 °C | 4.5 mK |
| Zinc Freezing Point | 419.527 °C | 4.5 mK |
| Aluminum Freezing Point | 660.323 °C | 7.0 mK |
| Silver Freezing Point | 961.78 °C | 12 mK |
The fixed points are selected according to the temperature ranges of the ITS-90. The temperature ranges of the ITS-90 are as follows:
Before calibration, the Standard Platinum Resistance Thermometer (SPRT) is sufficiently aged. Hydrostatic pressure effects that occur in the fixed-point cells are corrected. The self-heating of the Standard Platinum Resistance Thermometer (SPRT) is examined before the calibration begins and is taken into account when presenting the calibration results. The calibration results include the resistance and W-values of the Standard Platinum Resistance Thermometer (SPRT), as well as two calibration curves (coefficients) calculated according to ITS-90 (with measurement currents of 0 mA and 1 mA unless otherwise specified).
The calibration in the range from Argon (-189 °C) to the Water Triple Point (0.01 °C) additionally includes the specification of a measurement uncertainty for extrapolation according to EURAMET TG 01:2017 (up to the Nitrogen Boiling Point, ~196 °C) with a measurement uncertainty of 7 mK (k=2).
The minimum immersion depth of the Standard Platinum Resistance Thermometer (SPRT) is:
at -189 °C: 400 mm
at 962 °C: 450 mm
in range -38 °C to 660 °C: 300 mm
The maximum outer diameter is 8 mm.
Calibration duration: approximately 5-7 working days or as agreed.
Accredited calibration according to DIN EN ISO/IEC 17025 (DAkkS) of a resistance thermometer at temperature fixed points (PRT, Pt 100, Pt 1000)
The accredited calibration according to DIN EN ISO/IEC 17025 (DAkkS) of resistance thermometers (Pt100, Pt1000) is performed at ITS-90 fixed points.
learn more
Accredited calibration according to DIN EN ISO/IEC 17025 (DAkkS) of a resistance thermometer at the fixed points (melting points & triple points) of the ITS-90. Achievable DAkkS measurement uncertainties, including the ITS-90 deviation function (k=2):
| Temperature Fixed Point | in °C | Measurement Uncertainty |
| Argon Triple Point | -189.3442 °C | 10 mK |
| Mercury Triple Point | -38.8344 °C | 3.5 mK |
| Water Triple Point | 0.01 °C | 2.5 mK |
| Gallium Melting Point | 29.7646 °C | 2.5 mK |
| Indium Freezing Point | 156.5985 °C | 5.5 mK |
| Tin Freezing Point | 231.928 °C | 7.0 mK |
| Zinc Freezing Point | 419.527 °C | 12 mK |
| Aluminum Freezing Point | 660.323 °C | 20 mK |
The fixed points are selected according to the temperature ranges of the ITS-90. The temperature ranges of the ITS-90 are as follows:
Before calibration, the resistance thermometer is sufficiently aged. Hydrostatic pressure effects occurring in the fixed-point cells are corrected. The self-heating of the resistance thermometer is examined before the calibration begins and is taken into account when presenting the calibration results. The calibration results include the resistance and W-values of the resistance thermometer, as well as two calibration curves (coefficients) calculated according to ITS-90 (with measurement currents of 0 mA and 1 mA unless otherwise specified).
The minimum immersion depth of the resistance thermometer is:
at –189 °C: 400 mm
in range from -38 °C to 660 °C: 300 mm
The maximum outer diameter is 8 mm.
Calibration duration: approximately 5 working days or as agreed.
Accredited calibration according to DIN EN ISO/IEC 17025 (DAkkS) of a resistance thermometer via comparison calibration from -196 °C to 961 °C
Accredited calibration according to DIN EN ISO/IEC 17025 (DAkkS) of a resistance thermometer in the range from -196 °C to 961 °C.
learn more
Accredited calibration according to DIN EN ISO/IEC 17025 (DAkkS) of a resistance thermometer in a calibration bath or furnace, in a nitrogen cryostat, or at boiling nitrogen at 5 temperature points (distributed across the calibration range or as specified by the customer). The following measurement uncertainties can be achieved (depending on the test specimen):
| Calibration Range | Measurement Uncertainty | Calibration Method |
| -196 °C | 15 mK | Nitrogen Boiling Point |
| -180 °C to -80 °C | 60 mK | Nitrogen Cryostat |
| -80 °C to -60 °C | 15 mK | Calibration Bath |
| -60 °C to 90 °C | 10 mK | |
| 90 °C to 200 °C | 30 mK | |
| 200 °C to 500 °C | 40 mK | Calibration Furnace |
| 500 °C to 660 °C | 50 mK | |
| 660 °C to 961 °C | 150 mK |
Before calibration, the resistance thermometer is sufficiently aged. The self-heating and hysteresis of the resistance thermometer are examined before the start of the calibration and are taken into account when presenting the calibration results.
Calibration duration: approximately 5 working days or as agreed.
Accredited comparison calibration according to DIN EN ISO/IEC 17025 (DAkkS) of non-noble metal thermocouples, e.g., Type N
Comparison calibration of non-noble metal thermocouples against reference thermocouples.
learn more
Comparison calibration of non-noble metal thermocouples against reference thermocouples
Comparison calibration against reference thermocouples.
DAkkS measurement uncertainty:
| Temperature Range | Measurement Uncertainty | Calibration Method |
| -196 °C | 1.0 K | Nitrogen Boiling Point |
| -180 °C to -80 °C | 1.0 K | Nitrogen Cryostat |
| -80 °C to 0 °C | 1.0 K | Calibration Bath |
| 0 °C to 961 °C | 1.5 K | Calibration Furnace |
| 961 °C to 1200 °C | 2.5 K |
The minimum immersion depth of the thermometer is 190 mm (at -196 °C: 300 mm).
The maximum outer diameter is 8 mm.
The achievable measurement uncertainties depend on the test specimen.
Calibration duration: approximately 5 working days or as agreed.
Technical background
Calibrating thermometers at extremely low temperatures is a technical challenge. Conventionally, calibration baths or temperature block calibrators are used to calibrate thermometers in the negative temperature range. However, these quickly reach their limits when cooling and are only used down to around -80 °C.
Calibration baths are cooled with compressors. To ensure stable control of the calibration temperature, an electric heater works ‘against’ the compressor, which always cools at maximum power. In addition, the calibration media used (such as silicone or ethanol) change their viscosity considerably and absorb water from the ambient humidity. Both of these factors make it difficult to control the temperature of the calibration baths. The lowest temperature that calibration baths with stable control can reach is around -80 °C.
Temperature block calibrators are cooled with Peltier elements or Sterling motors. These technologies are limited and can be used down to about -50 °C with Peltier elements or -100 °C with Sterling motors.
To overcome these limitations, we use liquid nitrogen as a ‘cold source’. This enables us to extend the temperature range when calibrating thermometers down to -196 °C.
New digital archive Klasmeier Cloud:
Calibration documents quickly and easily available
The new Klasmeier Cloud – the perfect archive for all calibration documents. From now on, our customers will find a QR code on all devices calibrated by Klasmeier, with which they can quickly and easily access our digital archive.
Especially useful: In addition to all calibration documents, the contact details of the relevant contact person at Klasmeier are also always available there. So even five or more years from now, if you have any questions about your calibration product, you can find the information you need with just one click.
Finding the right calibration solution for you
Questions about our calibration services?
Please send your questions or enquiries to Mr Boris Kalb: