Paul N. Gardner Offers Bacharach Sling Psychrometer

Paul N. Gardner USA introduced the compact, portable Sling Psychrometer, an easy way to measure relative humidity levels quickly and accurately.

The compact, portable Bacharach Sling Psychrometer accurately determines percent relative humidity without the necessity of consulting complex tables. There is no need to wet the wick each time a reading is taken; the Sling Psychrometer contains a slide rule calculator which correlates wet and dry bulb thermometer indications for direct reading of relative humidity.

The Sling Psychrometer consists of two thermometers that are turned by vigorously swinging the handle and exposing the thermometers to rapid air movement. These two thermometers are called dry bulb and wet bulb.

The bulb of one thermometer is placed in direct contact with the room air to measure dry-bulb air temperature. The bulb of the other thermometer is covered with a silk or muslin sleeve that is kept moist to record the wet bulb temperature. Evaporation cools the wet bulb more than the dry bulb, and the humidity is obtained as a function of change in temperature. The atmospheric humidity is determined by calculations, steam tables, or using a psychrometric chart.