Calibration of dew-point measuring hygrometers against an NPL primary standard or a transfer standard in the range -90 °C to +90 °C.

The following calibrations are available within this area:

Image courtesy of iStockphoto

Calibration against an NPL primary standard, uncertainties in applied condition
+90 °C to +80 °C, uncertainty ±0.1 °C to ±0.04 °C
+80 °C to +60 °C, uncertainty ± 0.04 °C to ±0.03 °C
+60 °C to -60 °C, uncertainty ±0.03 °C
-60 °C to -75 °C, uncertainty ±0.03 °C to ±0.1 °C
-75 °C to -90 °C, uncertainty ±0.1 °C to ±0.5 °C

Calibration against an NPL transfer standard, uncertainties in applied condition
+90 °C to -49 °C, uncertainty ±0.2 °C to ±0.1 °C
-49 °C to -69 °C, uncertainty ±0.1 °C to ±0.2 °C
-69 °C to -90 °C, uncertainty ±0.2 °C to ±0.8 °C

Dew-point hygrometers with separate measuring head can be accommodated in a temperature-controlled chamber at above the dew-point temperature.

Uncertainties stated on certificates are the combination of the values due to the applied condition together with a contribution from the hygrometer resolution and stability during calibration.

Calibrations can cover other humidity units directly related to dew point, e.g. vapour pressure, amount fraction, vapour density (g/kg), etc.

Contact

Customer Service tel: +44 20 8943 8681
E-mail: humidity_enquiries@npl.co.uk