Whirling Hygrometer / Psychrometers - Humidity Reader
The Whirling Hygrometer Sling Psychrometer offers the maximum level of accuracy for the measurement of relative humidity utilising wet and dry bulb Red Spirit filled thermometers. The unit incorporates a water reservoir linked to the wet bulb by the means of a cotton sleeve. The Humidity is calculated using a water-soaked cotton sleeve at the bulb of the wet-bulb thermometer, how quickly the water evaporates alters the temperature of the wet-bulb thermometer. Using the specialist chart included allows you to calculate the relative humidity. Used to measure relative humidity.
How it works
When a reading is to be taken, the wick is first dipped in water and then the instrument is whirled around. During the whirling, the water evaporates from the wick, cooling the wet-bulb thermometer. Then the temperatures of both thermometers are read.
If the surrounding air is dry, more moisture evaporates from the wick, cooling the wet-bulb thermometer more so there is a greater difference between the temperatures of the two thermometers. If the surrounding air is holding as much moisture as possible - if the relative humidity is 100% - there is no difference between the two temperatures. Meteorologists have worked out charts of these differences for each degree of temperature so that the observer can find relative humidity easily.
Humidity tables supplied.
Handle folds inwards