Humidity and Temperature Calibration

The most comprehensive temperature, humidity and dew-point calibration offering on the market today.


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Michell Instruments and Rotronic, market leaders in the field of humidity and trace moisture measurements, offer a full range of temperature and humidity calibration equipment and systems.

These include transportable humidity generators for simple verification of relative humidity and temperature probes, pressure swing dryers and low dew point generators for calibrating trace moisture sensors and instruments. As well as building custom-designed humidity and dew-point calibration systems, we also provide ISO/IEC 17025 accredited relative humidity and temperature calibrations in six locations around the world.

Chilled Mirror Reference Hygrometers

Michell Instruments’ chilled mirror reference hygrometers provide fundamental, low-drift measurements of dew-point. Use in combination with the Rotronic or Michell humidity generators for calibrations traceable to NPL and NIST national standards.

Transportable Humidity Generators and Automatic Humidity Calibration Systems

For cost-effective humidity calibrations on-site, these stable and reliable humidity generators can be used in combination with a chilled mirror reference for full traceability. Fully automatic, computer-controlled humidity calibration systems provide humidity generation, a climatic chamber and chilled mirror reference for professional calibrations.

Trace Moisture Calibration Systems

Complete dew-point calibration package with optional compressor, dryer, dew-point generator, reference instrument and optional manifold. Capable of providing trace moisture calibrations down to -100 °C dew point

Humidity and Temperature Calibration Services

We have humidity, temperature and dew point calibration facilities located all over the world. Six locations are accredited by the relevant national accreditation agencies. Find out more about our ISO/IEC 17025 calibration facilities.


  • Calibration is the comparison of an instrument against a reference. The reference should itself have calibration traceable directly, or in multiple steps, back to an authoritative standard. This is known as measurement traceability.

  • Calibration improves measurement confidence, enables entities to meet regulatory requirements, enables traceability and provides additional data about the sensor (like drift, repeatability and errors when compared to the reference). It is a vital part of instrument maintenance.

  • The most common approach is calibrating both the relative humidity and temperature circuits of the device. This is done by using a calibration chamber (like Rotronic's HG2-S) which generates required humidity and temperature conditions. Relative humidity sensors can also be calibrated at ambient temperature and can be achieved by using either saturated or non-saturated salt solutions or humidity validators.

  • Rotronic's HG2-S and HG2-XL calibration chambers are designed to create the precise humidity and temperature conditions. The chambers are fully sealed, ensuring that any variations in humidity within the chamber are solely due to temperature fluctuations. Humidification is achieved through a water reservoir, while a desiccant system is used for drying. Both the HG2-S and HG2-XL models are equipped with an ISO17025 calibrated control probe, which serves as a reliable calibration reference.

  • Some of the contributors to the uncertainty budget include reference error, resolution, and thermal gradients. Calibration facilities dedicate significant effort to reducing these uncertainties to enhance accuracy. For in-house calibration departments, the primary source of uncertainty often lies in the reference instrument and the calibration methodology employed.

  • Accuracy and Precision: The accuracy should align with your requirements, considering the specific applications and standards you need to meet. Range of Measurement: The humidity and temperature range the device can accurately calibrate. Stability: The device should maintain consistent performance without significant drift in readings over the period you intend to use it. Traceability: Ensure that the calibration reference calibration is traceable to national or international standards. Cost: The cost of the device should fit within your budget while meeting your technical requirements.

  • ISO/IEC 17025 is the principal standard adopted by calibration and testing laboratories. While adherence to ISO 17025 is not compulsory for all facilities, it is obligatory for those who are audited against this standard. If ISO 17025 is not a necessity, we strongly advise following good measurement practices to ensure the integrity of your calibrations.

  • PST offers a diverse portfolio that includes everything from unsaturated salt solutions and validators to state-of-the-art calibration chambers, as well as advanced chilled mirror hygrometers and dew point generators. Our rich experience and specialized knowledge have fostered strong relationships with leading National Measurement Institutions such as the National Physical Laboratory (NPL) in the UK and the National Institute of Standards and Technology (NIST) in the US.

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