The Whirling Hygrometer or sling psychrometer is an established, well-known method for determining the relative humidity and dew point. 

The sling psychrometer is used by paint shops to determine if there is any moisture on steel to prior to painting, as well as, and an economical choice for educators.

Our sling psychrometers allow you to obtain fast and accurate humidity readings anywhere by comparing the reading of the wet and dry bulb thermometers on the enclosed humidity chart. Eliminates the hazard of splattering mercury by using a safe and easy to read red liquid. The thermometers are recessed into a protective plastic mounting. The mounting also contains a water reservoir eliminating the need to constantly re-wet the wick. Comes with a carrying case and plastic humidity chart.

Dimensions: 9⅛" × 2" × ⅝" (232 × 51 × 16 mm)
Weight: 7.4 oz (210 g)