Accredited Calibration According to DIN EN ISO/IEC 17025 (DAkkS) of Thermometers at Low Temperatures
Do you need to calibrate thermometers at extremely low temperatures? Is the temperature range of conventional calibration baths and standardized procedures insufficient? 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 with accreditation according to DIN EN ISO/IEC 17025 (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
Our Services at a Glance
Ar
-189°C
ITS-90 Calibration
up 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 boiling nitrogen we can:
Thermocouples and resistance thermometers with freely selectable calibration temperatures between -180°C and -80°C in the nitrogen cryostat accredited according to DIN EN ISO/IEC 17025 (DAkkS)calibrate.
Utilize the boiling point of nitrogen and calibrate thermometers at -196°C accredited according to DIN EN ISO/IEC 17025 (DAkkS).
Operate the argon triple point at -189.3442°C and perform a complete ITS-90 accredited calibration according to DIN EN ISO/IEC 17025 (DAkkS) 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) SPRT 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.
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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 & triple points) of the ITS-90. Achievable DAkkS measurement uncertainties including 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 can be found here:
Before calibration, the Standard Platinum Resistance Thermometer (SPRT) is sufficiently aged. Hydrostatic pressure effects occurring in the fixed point cells are corrected. The self-heating of the Standard Platinum Resistance Thermometer (SPRT) is investigated before calibration begins and is taken into account when reporting calibration results. The calibration results include the resistance and W-values of the Standard Platinum Resistance Thermometer (SPRT), as well as two characteristic curves (coefficients) calculated according to ITS-90 (with measuring current 0 mA and 1 mA, unless otherwise specified).
Calibration in the range from argon (-189°C) to the water triple point (0.01°C) additionally includes specification of a measurement uncertainty for extrapolation according to EURAMET TG 01:2017 (down 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 the range -38°C to 660°C: 300 mm
The maximum outer diameter is 8 mm.
Calibration duration approx. 5-7 working days or by arrangement.
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.
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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 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 can be found here:
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 investigated before calibration begins and is taken into account when reporting calibration results. The calibration results include the resistance and W-values of the resistance thermometer, as well as two characteristic curves (coefficients) calculated according to ITS-90 (with measuring current 0 mA and 1 mA, unless otherwise specified).
The minimum immersion depth of the resistance thermometer is:
at –189°C: 400 mm
in the range -38°C to 660°C: 300 mm
The maximum outer diameter is 8 mm.
Calibration duration approx. 5 working days or by arrangement.
Accredited Calibration According to DIN EN ISO/IEC 17025 (DAkkS) Resistance Thermometer Comparison Calibration -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.
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Accredited calibration according to DIN EN ISO/IEC 17025 (DAkkS) of a resistance thermometer in a calibration bath or calibration furnace, in a nitrogen cryostat or at boiling nitrogen at 5 temperature points (distributed over the calibration range or according to customer requirements). The following measurement uncertainties can be achieved (depending on the device under test):
| Calibration Range | Measurement Uncertainty | Calibration Procedure |
| -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 investigated before calibration begins and are taken into account when reporting calibration results.
Calibration duration: approx. 5 working days or by arrangement.
Accredited Comparison Calibration According to DIN EN ISO/IEC 17025 (DAkkS) Base Metal Thermocouple e.g. Type N
Comparison calibration of base metal thermocouples against standard thermocouples.
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Accredited Calibration According to DIN EN IEC/ISO 17025 Base Metal Thermocouple
Comparison calibration against standard thermocouples.
DAkkS Measurement Uncertainty:
| Temperature Range | Measurement Uncertainty | Calibration Procedure |
| -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 device under test.
Calibration duration approx. 5 working days or by arrangement.
Technical Background
Calibrating thermometers at extremely low temperatures is a technical challenge. Conventionally, calibration baths or temperature block calibrators are used for calibrating thermometers in the negative temperature range. However, these quickly reach their limits when cooling and are only used down to approx. -80°C.
Calibration baths are cooled with compressors. For 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 significantly and absorb water from ambient humidity. Both factors complicate the temperature control of calibration baths. The lowest temperature that calibration baths can achieve with stable control is approx. -80°C.
Temperature block calibrators are cooled with Peltier elements or Stirling engines. These technologies are limited and can be used down to approx. -50°C with Peltier elements or -100°C with Stirling engines.
To overcome these limitations, we use liquid nitrogen as a “cold source”. This enables us to extend the temperature range for calibrating thermometers down to -196°C.
Klasmeier Cloud Digital Archive:
Calibration Documents Quickly and Easily Accessible
The Klasmeier Cloud – the perfect storage system for all calibration documents. On all devices calibrated by Klasmeier, you will find a QR code that provides quick and easy access to our digital archive.
Particularly practical: In addition to all calibration documents, you will also find the contact details of the respective contact person at Klasmeier. This way, even in five or more years, you can find the information you need with just one click if you have questions about your calibration product.
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