DAkkS Calibration of Standard Thermometers (SPRT)
The DAkkS calibration of ITS-90 standard thermometers (SPRT) is done at ITS-90 fixed points.
Full range DAkkS calibration from argon triple point to silver freezing point
Use of state-of-the-art temperature fixed points
Triple set of temperature fixed points available
Turnaround time is five working days
Temperature probes can be calibrated from a length of 300 mm
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.
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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, 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 based on the temperature ranges of the ITS-90. The temperature ranges of the ITS-90 are as follows:
Prior to 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 examined before the start of the calibration and taken into account in 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 in accordance with 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 bis 660 °C: 300 mm
The maximum outer diameter is 8 mm.
Calibration duration: approximately 5-7 working days or as agreed.
Uncertainty of measurement during DAkkS calibration
| Temperature range | Procedure | Uncertainty of measurement |
|---|---|---|
| -196 °C to -189,3442 °C | EURAMENT TG 01:2017 | 7,0 mK * |
| -189,3442 °C | G-ITS-90, Part 2.3:2021 Argon triple point | 4,0 mK |
| -38,8344 °C | G-ITS-90, Part 2.4:2021 Mercury triple point | 2,5 mK |
| 0,01 °C | G-ITS-90, Part 2.2:2018 Water triple point | 1,5 mK |
| 29,7646 °C | G-ITS-90, Part 2.4:2021 Gallium melting point | 2,0 mK |
| 156,5985 °C | KA16-10-02:2020-01 Indium melting point | 4,5 mK |
| 231,928 °C | G-ITS-90, Part 2.4:2021 Tin freezing point | 3,0 mK |
| 231,928 °C | KA16-10-05:2022-08 Tin melting point | 6,0 mK |
| 419,527 °C | G-ITS-90, Part 2.4:2021 Zinc freezing point | 3,0 mK |
| 419,527 °C | KA16-10-05:2022-08 Zinc melting point | 10 mK |
| 660,323 °C | G-ITS-90, Part 2.4:2021 Aluminium freezing point | 5,0 mK |
| 660,323 °C | KA16-10-05:2022-08 Aluminium melting point | 18 mK |
| 961,78 °C | G-ITS-90, Part 2.4:2021 Silver freezing point | 10 mK |
* Extrapolation
| Temperature range | Procedure | Uncertainty of measurement |
|---|---|---|
| -189,3442 °C to 0,01 °C | G-ITS-90, Part 5:2021 fixed points: Ar, Hg, TPW | 5,5 mK |
| -38,8344 °C to 29,7646 °C | G-ITS-90, Part5:2021 fixed points: Hg, TPW, Ga | 3,5 mK |
| 0 °C to 29,7646 °C | G-ITS-90, Part5:2021 fixed points: TPW, Ga | 2,5 mK |
| 0 °C to 156,5985 °C | KA16-10-05:2022-08 fixed points: TPW, In melting points | 5,5 mK |
| 0 °C to 231,928 °C | KA16-10-05:2022-08 fixed points: TPW, In, Sn melting points | 7,0 mK |
| 0 °C to 419,527 °C | G-ITS-90, Part5:2021 fixed points: TPW, Sn, Zn | 4,5 mK |
| 0 °C to 419,527 °C | KA16-10-05:2022-08 fixed points: TPW, Sn, Zn melting points | 12 mK |
| 0 °C to 660,323 °C | G-ITS-90, Part5:2021 fixed points: TPW, Sn, Zn, Al | 7,0 mK |
| 0 °C to 660,323 °C | KA16-10-05:2022-08 fixed points: TPW, Sn, Zn, Al melting points | 20 mK |
| 0 °C bis 961,78 °C | G-ITS-90, Part5:2021 fixed points: TPW, Sn, Zn, Al, Ag | 12 mK |
Calibration at temperature fixed points
Klasmeier’s calibration service calibrates standard thermometers (SPRT) by using ITS-90 temperature fixed points. Depending on the customer’s requirements, slim temperature fixed points with greater measurement uncertainties and primary “large” ITS-90 temperature fixed points in heat pipes or ISO towers with excellent measurement uncertainties can be used. The order of the fixed points at which calibration is performed results in falling temperatures for SPRT’s. To exclude thermometer drift, the water triple point is measured after each fixed point measurement and thus the drift of the temperature probe is controlled. In addition, each resistance thermometer is annealed at the highest operating temperature before calibration and the annealing drift is determined with the use of the water triple point. Self-heating errors and hydrostatic pressure effects are analysed and taken into account during calibration. The DAkkS calibration certificate is internationally accepted and can also be used abroad.
Short immersion depth from 300mm
By using slim and large temperature fixed points, as well as the modern ISO towers, standard thermometers of the ITS-90 (SPRTs as Pt100 or Pt25) can be calibrated from an immersion depth of 300mm with excellent measurement uncertainties.
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: