4-25. WET BULB GLOBE TEMPERATURE (WBGT) INDEX
The wet bulb globe temperature (WBGT) index is a method of combining the three
readings obtained from the WBGT apparatus. All readings are to be in degrees
Fahrenheit. The index, however, is a number--not a temperature.
Formula. The WBGT Index is computed as follows:
a. Formula. The WBGT Index is
b. Example. An example of a
computed as follows:
WBGT computation follows:
0.7 x wet bulb temperature
Wet bulb temperature = 80 F
+0.2 x black globe temperature
Black bulb temperature = 105 F
+ 0.1 x dry bulb temperature
Dry bulb temperature = 90 F
80 x 0.7 = 56
4-26. OTHER INDEXES
a. Wet Globe Temperature (WGT) Index. The wet globe temperature index is
determined using a Botsball apparatus (Figure 4-2).
Figure 4-2. Botsball apparatus.
The Botsball consists of a thermometer with a dial gauge whose bulb is
enclosed in a small copper globe.