National Physical Laboratory

Humidity calibration salts

Calibrations can be provided for capsules, ampoules or other suitable artefacts that use salt solutions or other chemical substances to generate stable values of humidity.

Humidity calibration salts
Image courtesy of iStockphoto

Both re-usable or single-use types can be calibrated (single-use types by batch calibration).

Relative humidity range 1 %rh to 98 %rh at temperatures from 10 °C to 50 °C (or enquire for temperatures outside this range).

Uncertainties stated on certificates are the combination of the values due to the reference instrument, together with the stability of the artefact during measurement.

Values assigned to a batch of salt capsules or ampoules, are based on random sampling from the batch. Uncertainty assigned to a batch value depends on the measurement uncertainty together with the sample size and the variation within the sample.

Further information about using salts for humidity generation and calibration (FAQ).


Customer Service tel: +44 20 8943 8681

Last Updated: 11 Dec 2017
Created: 15 Apr 2009


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