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Cambridge Building Energy & Environment Portal

whirling hygrometer


The whirling hygrometer offers the maximum level of accuracy due to the nature of measurement. Housed in a robust yellow plastic frame and black folding handle, the instrument incorporates a water cistern linked to the "wet" bulb by means of a cotton sleeve. The whirling hygrometer is whirled rapidly for thirty seconds, after which time a reading of the two thermometers is taken, with the wet bulb thermometer normally read first. This is repeated until 2 consecutive readings are obtained which are comparable. Relative humidity can then be determined by correlating the readings with those on the hygrometric table supplied with each instrument. The whirling hygrometer comes complete with hygrometric tables and a carrying case.


  • Measurement: percentage humidity in a room
  • Range: temperature -5 to 50°C; %RH 1-99%RH
  • Accuracy: %RH ±2%


Manual: whirling hygrometer