Precise Thermometer Calibration for the Highest Standards
Rely on our DAkkS-accredited calibration according to DIN EN ISO/IEC 17025 for your Standard Platinum Resistance Thermometers (SPRTs).
We calibrate your SPRTs across the full temperature range of ITS‑90 and guarantee the highest accuracy and traceability to international standards.
Our Services
Accredited calibration of SPRTs (length ≥ 300 mm)
Temperature range: –196 °C to +961 °C – full ITS‑90 coverage
Calibration method: fixed-point calibration at ITS‑90 fixed points
Selectable calibration accuracy – from melting-point to high-end freezing-point calibration
Suitability testing per DIN EN ISO/IEC 17043:2023
In-house repair service for SPRTs
Your Benefits
Full flexibility in accuracy
You choose:
Melting-point calibration
(cost-effective, slightly higher uncertainty)
High-end freezing-point calibration
(ultra-low uncertainty for highest demands)
Fast turnaround in 5 working days
→ Minimize downtime – your reference thermometers are ready quickly.
Minimal measurement uncertainties
→ Achieve the highest precision: we bring out the best
in your thermometer.
All-in-one solution
→ Complete package: calibration, suitability testing,
repair – all under one roof.
Central location in Fulda Germany
→ Easily accessible – drop off your SPRT or use our secure courier service.
Paperless documentation
→ Legally signed and accessible at any time via our modern cloud solution.
Details of Our SPRT Calibration Service
Why individual calibrations for SPRTs?
An SPRT is the most precise instrument for realizing the International Temperature Scale (ITS‑90). To unlock its full potential, it must be precisely and individually calibrated at defined fixed points. This ensures reliable results, compliance with standards, and avoids costly errors.
Our services
| Service | Temperature range | Method | Typical expanded uncertainty* |
| Full-range calibration | –189 °C … 660 °C | Melting‑ or freezing-points | up to 3 mK |
| Partial-range calibrations | User‑selectable ITS‑90 segment (e.g. 0 °C … 419 °C) | Melting‑ or freezing-points | 2 – 6 mK |
| Extension modules | Additional fixed points for non-standard ranges (Argon, Mercury, Gallium, Indium) same as base calibration | like basic calibration | 2–10 mK |
* All uncertainties given for k = 2 (~95 % confidence).
Two proven methods – melting vs freezing points
| Method | Typical measurement uncertainties* | Cost factor* | Advantages | Typical turnaround |
| Melting-point calibration (developed & accredited by Klasmeier) | Argon 10 mK Hg 3,5 mK WTP 2,5 mK Ga 2,5 mK Sn 7 mK Zn 12 mK Al 20 mK | ~50 % of freezing‑point calibration cost | • Economical • Uncertainty sufficient for many applications • Ideal for reference thermometers using comparison method | about 5 working days |
| Freezing-point calibration (most accurate ITS‑90 realization) | Argon 4 mK Hg 2,5 mK WTP 1,5 mK Ga 2 mK Sn 3 mK Zn 3 mK Al 5 mK | Reference | • Highest precision • Ideal for primary standards | about 7 working days |
* k = 2, including ITS‑90 deviation function (if specified).
** Example comparison using full-range packages (KK‑1413 vs KK‑1404). Depending on segment, difference ~40–60 %. All data per our price list.
Conclusion: For highest accuracy (e.g. primary standards), freezing-point calibration is recommended. For less-critical references (e.g. secondary calibrations), Klasmeier’s melting-point calibration offers a far more economical choice with excellent overall uncertainty.
Measurement Uncertainties and Article Numbers of SPRT Calibration at Klasmeier (k=2)
| Art.-No. | Temperature range (°C) | Fixed points & Expanded Uncertainty |
| KK‑1404 | –189 … 660 °C | Ar 10 mK, Hg 3,5 mK, WTP 2,5 mK, Ga 2,5 mK, Sn 7 mK, Zn 12 mK, Al 20 mK |
| KK‑1424 | –189 … 660 °C | Ar 4 mK, Hg 2,5 mK, WTP 1,5 mK, Ga 2,0 mK, Sn 3 mK, Zn 3 mK, Al 5 mK |
| KK‑1402 | 0 … 660 °C | WTP 2,5 mK, Ga 2,5 mK, Sn 7 mK, Zn 12 mK, Al 20 mK |
| KK‑1401 | 0 … 660 °C | WTP 1,5 mK, Ga 2,0 mK, Sn 3 mK, Zn 3 mK, Al 5 mK |
| KK‑1411 | 0 … 419 °C | WTP 1,5 mK, Ga 2,0 mK, Sn 3 mK, Zn 3 mK |
| KK‑1408 | 0 … 419 °C | WTP 2,5 mK, Ga 2,5 mK, Sn 7 mK, Zn 12 mK |
| KK‑1409 | 0 … 230 °C | WTP 2,5 mK, Ga 2,5 mK, In 5,5 mK, Sn 7 mK |
| KK‑1413 | 0 … 156 °C | WTP 1,5 mK, Ga 2,0 mK, In 4,5 mK |
| KK‑1410 | 0 … 29 °C | WTP 1,5 mK, Ga 2,0 mK |
| KK‑1405 | –189 … 29 °C | Ar 4 mK, Hg 2,5 mK, WTP 1,5 mK, Ga 2,0 mK |
| KK‑1412 | –189 … 29 °C | Ar 10 mK, Hg 3,5 mK, WTP 2,5 mK, Ga 2,5 mK |
| KK‑1400 | –38 … 29 °C | Hg 2,5 mK, WTP 1,5 mK, Ga 2,0 mK |
| KK‑1406 | –38 … 29 °C | Uncertainties upon request |
The stated values apply directly at the respective fixed points.
Uncertainties in intermediate ranges typically increase by about 0,5 – 2 mK.
Scope of Services for SPRT Calibration
DAkkS-accredited calibration according to DIN EN ISO/IEC 17025 for standard thermometers (WGa = 1.11807, WHg = 0.844235) at freezing, melting, and triple points per ITS-90.
Minimum uncertainties at fixed points (k=2):
- Argon −189,3442 °C – 4,0 mK
- Quecksilber −38,8344 °C – 2,5 mK
- Wasser‑Tripelpunkt 0,01 °C – 1,5 mK
- Gallium 29,7646 °C – 2,0 mK
- Zinn 231,928 °C – 3,0 mK
- Zink 419,527 °C – 3,0 mK
- Aluminium 660,323 °C – 5,0 mK
Uncertainties depend also on the individual thermometer and method. Please consider specific uncertainty statements.
Extrapolation to nitrogen boiling point (−196 °C)
7 mK uncertainty according to EURAMET TG 01:2017 when calibrated at argon triple point.
ITS‑90 Deviation Functions
Included for each interval; uncertainties are only 0.5–2 mK higher than fixed-point values.
Thermometer Pre-treatment & Corrections
– Pre-annealing (stabilization) of SPRT
– Correction of hydrostatic pressure effects in fixed-point cells
– Determination and compensation of self-heating
Scope of Calibration Documentation
– Resistance and W-values at each fixed point
– ITS-90 coefficients for measurement currents of 0 mA and 1 mA
– DAkkS calibration certificate with complete measurement protocol
Technical Requirements
All SPRT calibrations must fulfill ITS-90 conditions: WGa = 1.11807 or WHg = 0.844235. If not, please read further here: Calibration of resistance thermometers or contact us for additional info. Your thermometer can still be calibrated at temperature fixed points, but more economically.
| Applies to | Min. immersion depth | Max. outer diameter |
| KK‑1404, KK‑1424, KK‑1405, KK‑1400, KK‑1428, KK‑1423, KK‑1413 | 400 mm | 8 mm |
| KK‑1401, KK‑1402, KK‑1408, KK‑1409, KK‑1410, KK‑1411, KK‑1412 | 300 mm | 8 mm |
All other articles follow the same limitations as stated in the offer.
Optional Extension Modules (Additional Fixed Points)
Extend your existing ITS-90 calibration by additional fixed points for broader temperature coverage.
| Art.-No. | Additional Fixed Points | Uncertainty (k=2) | Description |
| KK‑1428 | Argon −189 °C Hg −38 °C | 10 mK (Ar) 2,5 mK (Hg) | Additional fixed points (higher uncertainty) |
| KK‑1423 | Argon −189 °C Hg −38 °C | 4 mK (Ar) 2,5 mK (Hg) | Additional fixed points (higher uncertainty) |
| KK‑1425 | Gallium 29,8 °C | 2 mK (Ga) | Additional fixed point (Ga) |
| KK‑1426 | Indium 156,6 °C | 4,5 mK (In) | Additional fixed point (In) |
| KK‑1424 | Hg −38 °C Gallium 29,8 °C | 2,5 mK (Hg) 2 mK (Ga) | Additional fixed points (Hg, Ga) |
All modules up to argon triple point include extrapolation to nitrogen boiling point (−196 °C). Immersion depth and diameter as in basic calibration (~400 mm / 8 mm).
Calibration prices – Overview
| Art.-No. | Temperature range | Method | Category | Price (EUR) |
| KK‑1404 | –189 … 660 °C | Freezing- & triple points | Full Range | 3.265 € |
| KK‑1413 | –189 … 660 °C | Freezing- & triple points | Full Range | 2.600 € |
| KK‑1402 | 0 … 660 °C | Freezing- & triple points | Section | 2.530 € |
| KK‑1412 | 0 … 660 °C | Melting- & triple points | Section | 1.970 € |
| KK‑1401 | 0 … 419 °C | Freezing- & triple points | Section | 2.000 € |
| KK‑1411 | 0 … 419 °C | Melting- & triple points | Section | 1.705 € |
| KK‑1410 | 0 … 230 °C | Melting- & triple points | Section | 1.625 € |
| KK‑1409 | 0 … 156 °C | Melting- & triple points | Section | 1 535 € |
| KK‑1408 | 0 … 29 °C | Melting- & triple points | Section | 1.204 € |
| KK‑1405 | –189 … 29 °C | Melting- & triple points | Section | 2.030 € |
| KK‑1400 | –189 … 29 °C | Melting- & triple points (higher accuracy) | Section | 2.665 € |
| KK‑1406 | –38 … 29 °C | Melting- & triple points | Section | 1.521 € |
| KK‑1428 | –189 °C + –38 °C | Additional fixed points (Ar, Hg) | Extension | 795 € |
| KK‑1423 | –189 °C + –38 °C | Additional fixed points (Ar, Hg) | Extension | 930 € |
| KK‑1425 | 29 °C | Additional fixed points (Ga) | Extension | 184 € |
| KK‑1426 | 156 °C | Additional fixed points (In) | Extension | 286 € |
| KK‑1424 | –38 °C + 29 °C | Additional fixed points (Hg, Ga) | Extension | 460 € |
All prices are net; shipping and insurance costs are not included.
All prices and uncertainties are for information purposes only and are taken from our specifications.
New: Digitally Signed Calibration Certificates with Official Accreditation Symbol
Our calibration certificates now feature a digital accreditation symbol officially introduced by DAkkS, making your calibration documents legally valid, digitally signed, and verifiable.
Your benefits
- Tamper-proof and verifiable
- Legally binding and internationally accepted
- Digital access anywhere, anytime
- Zukunftssicher Audit-proof and future-oriented
More information directly at DAkkS:
Calibration at temperature fixed points
Our calibration service uses ITS‑90 fixed-point cells. Depending on customer needs, slim melting-point cells (higher uncertainty) and primary “large” ITS‑90 fixed-point cells in heat-pipes or ISO towers (excellent uncertainty) are used. Calibration points for SPRTs are performed in descending temperature order. To exclude thermometer drift, we determine the water triple point after each measurement.
Additionally, each thermometer is pre-aged at its highest operating temperature; the aging drift is determined using the water triple point. We also investigate and compensate for self-heating and hydrostatic pressure effects. The DAkkS calibration certificate issued is internationally recognized and valid abroad.
Small immersion depth from 300 mm
Using both slim and large fixed-point cells and modern ISO towers, we can calibrate SPRTs (Pt 100 or Pt 25) from 300 mm immersion depth with outstanding uncertainty.
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.
Klasmeier – because precise temperature measurement is a matter of trust.
Your detailed advantages:
Customizable calibration precision
→ You determine the required precision of your calibration—and thus control the cost.
In-house manufacturing & expert service
→ We produce our own sensors and professionally repair SPRTs—short distances, no third-party providers.
Complete peace-of-mind package
→ Calibration, proficiency testing, consulting, and documentation—with us, you are audit-ready and legally compliant.
Digital efficiency
Calibration data and device information available online anytime—secure, convenient, and GDPR-compliant.
Added value for audits & consulting
We can provide support for your audit preparations:
Accredited calibrations covering the entire ITS‑90 range
→ Ensuring you’re fully prepared for your next audit.
Proficiency tests to validate your measurement uncertainties
Practical tips and expert consulting from an accredited laboratory
→ Ensuring your temperature measurement solutions perform convincingly—not just on paper, but in daily operations.
Finding the right calibration solution for you
Questions about our calibration services?
Please send your questions or enquiries to Mr Boris Kalb: