Temperature Sensor Calibration: Points, Certificates and Intervals
Why calibrate a temperature sensor?
A calibration certificate tells you how much the sensor deviates from a reference at defined points. It does not make the sensor more accurate, but it gives you a documented correction and confidence for quality, safety and maintenance decisions.
Calibration is especially important for:
- Pharmaceutical and food processes
- Laboratories and metrology
- Furnaces and heat treatment
- Applications with tight accuracy or regulatory requirements
What points should be calibrated?
Choose points that cover the working range, not just one temperature. For a Pt100 used from 0 to 100 °C, common points are 0 °C, 50 °C and 100 °C. For a sensor used around 37 °C, include that point.
For thermocouples, calibration at several points also reveals drift and type errors.
What should the certificate contain?
A useful calibration certificate should include:
- Sensor identification: model, serial number, range
- Calibration points and the reference reading
- Indicated value, error and uncertainty
- Calibration method and reference standard
- Date of calibration and recommended next date
- Laboratory accreditation mark, where applicable
Ask whether the certificate is accredited (for example CNAS) and whether the uncertainty meets your requirement. A certificate with a large uncertainty may not support a tight process tolerance.
Calibration interval
The right interval depends on the sensor, environment and criticality:
- Laboratory reference sensors: often annual
- Industrial Pt100 in clean service: 1–2 years
- Thermocouples in furnaces: 6–12 months, depending on temperature and atmosphere
- Sensors in critical processes: shorter intervals or before each campaign
A drift history from previous calibrations is the best guide.
In-house vs external calibration
In-house calibration is practical for routine checks with a bath or dry-block calibrator. External calibration is appropriate when you need accredited uncertainty, a wider range or a documented traceability chain.
How to improve calibration results
- Use a 3- or 4-wire connection for Pt100
- Keep the sensor and reference at the same depth and in the same medium
- Allow enough stabilisation time
- Check the transmitter separately from the sensor
- Record the as-found and as-left readings
Our high-precision Pt100 sensor can be supplied with a calibration certificate. Use the Pt100 calculator to compare resistance and tolerance values.
Need a calibrated sensor or advice on points and uncertainty? Contact our team.