7 Measurements
WetBulb Globe Temperature (WBGT)
Measurements
The QUESTemp
48N data logging, with an event logging mode, heat stress monitor directly
senses three parameters: dry bulb temperature (DB), globe temperature (G), and relative
humidity (RH).
It computes the Wet Bulb (WB), the Wet Bulb Globe Temperature (WBGT), and the Stay
Times Indices for ACGIH, U.S. Navy PHEL charts, and Flag Conditions for U.S. Navy/Marine
Corp. Ashore.
WetBulb Globe Temperature (WBGT)
The WBGT is a type of temperature index which combines the effects of temperature,
humidity, radiant heat, and air flow and provides a relatively simplistic tool to analyze thermal
comfort. The resulting WBGT values can then be compared to indices of work-rest regimens
(stay times) based upon workloads.
The WBGT calculation is a weighted average of the three temperature sensors using the
following formulas:
**
NOTE
: Navy and Marine calculations are all based on the outdoor computation.
WBGT (outdoor) = 0.7WB + 0.2G + 0.1DB (denoted as “WBGT” on the display)
Stay Times/Rest Times (Indicies)
Stay Times Indices represent how long a worker should be able to safely work under heat
stress conditions. Select one of four indices for displaying and printing from the unit: ACGIH
Stay Times, NAVY PHEL’s, or Flag Conditions for U.S. Navy/Marine Corp. Ashore. Refer to
Appendix B for more information on the indices.
NOTE
: It will appear as “Index” on the measurement screen.
Remote measurements
The top sensor bar may be removed from the instrument and used through a remote cable.
(Refer to Appendix C for remote cable options.) Shelter the instrument and remote the sensor
bar if the measured environment is expecting heavy rain or if temperatures are above 60°C.
Measurements
