ECD SmartDRY SD Series Setup And Operation Manual page 113

Wet Bulb, Dry Bulb (AKA: Psychrometer):
The name of this method is derived from the spinning of two thermometers through the air to take advantage
of the wind chill effect on one verses the dry temperature on the other. One of the older procedures for calcu-
lating humidity, this technique measures two temperatures, one from a wet bulb and one from a dry bulb. The
bulbs are the reservoir end of two glass thermometers. One bulb is kept wet with a "sock" or wick, and one is
maintained at the ambient temperature (dry). The chilling effect of the evaporating water on the wet bulb re-
duces the temperature and the difference between the two temperatures is a function of the relative humid-
ity. It's not a simple function, but it is one that is scientifically proven. Traditional glass thermometers are no
longer used and have been replaced with the temperature sensing elements of a digital thermometer. The ac-
curacy of the RH calculation depends on the accuracy of the temperature measurement, the purity of the wa-
ter and cleanliness of the sock used to keep the wet bulb wet, and good air flow over the sensors.
Typical manual Psychrometer
SD Series Dry Cabinets Setup and Operation Manual | A62-3337-00 Rev: 1.0.0 Page 107