Calibration Services

Temperature and Humidity: About Humidity Measurement

Humidity is a measure of the water vapour present in the air or in other gases. Because of the very wide interest in humidity, it is expressed in many different but inter-related ways. Those interested in very low concentrations, for instance, would probably express their measurements in parts per million; others concerned with higher levels of humidity are more likely to specify dew-point or partial pressure of water vapour; and those interested in the effect of water vapour on materials usually prefer measurements in relative humidity.

The Laboratory maintains the official reference standards of humidity measurements for Hong Kong.

The Laboratory provides calibration services for the following types of instruments:

1. Dew-point instruments, Range : -60°C to 65°C.
2. Psychrometers.
3. Electronic relative humidity instruments.
4. Thermohygrographs/Temperature and humidity recorders.
5. Humidity Calibrators / Humidity Generators (Quotation can be provided upon request.)

For 2, 3 and 4, the temperature and humidity ranges are interrelated. The maximum ranges are:

• Temperature : 5°C to 70°C
• Humidity : 8% to 95% RH