What is wet bulb?
What is Wet Bulb Temperature?
Wet bulb temperature is measured by exposing a thermometer bulb wrapped in muslin and moistened with distilled water to the air flow. The humidity of the air determines the rate of evaporation from the wet bulb thermometer - the wet bulb temperature is lower when the air is full of water vapor. The wet bulb temperature is always lower than the dry bulb temperature, unless the relative humidity is 100% and then the two temperatures are identical.Wet bulb temperature readings were used before there were electronic relative humidity sensors. The wet bulb reading was used in conjunction with a regular thermometer reading in an instrument called a sling psychrometer. Comparing the two temperatures and adjusting them for a known altitude could determine the relative humidity. The sling is not an ideal way to determine the relative humidity or wet bulb temperature because it is large, bulky, delicate and very prone to user-error. Now that sophisticated and accurate humidity sensors are available, wet bulb temperature has become less and less used. Kestrel Meters use a patented RH sensor to measure the humidity, then calculates the wet bulb temperature.
So who uses wet bulb temperature, anyway? Chances are, if you aren’t familiar with wet bulb, your application doesn’t require it. Wildland firefighters, military personnel, heating, ventilation, air conditioning and refrigeration (HVAC/R) professionals, and scientific researchers are some Kestrel customers who need a wet bulb reading.
by NK Amy on August 9th, 2007, 4:41 pm
