Calibration of standard thermometers


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


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

Calibration at temperature fixed points.

* 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 to 961,78 °C G-ITS-90, Part5:2021 fixed points: TPW, Sn, Zn, Al, Ag 12 mK

Calibration at temperature fixed points with characteristic curve determination according to ITS-90. The measurement uncertainty refers to the characteristic curve in the specified range.

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.







Questions about calibration?

Contact: Boris Kalb –