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Measurements | Measurements |
Measurements
QUESTemp°32
The QUESTemp°32 portable area heat stress monitor computes the Wet Bulb Globe Temperature (WBGT). The WBGT is an accepted measurement for determining the heat stress level imposed on an individual in a given environment. The QUESTemp°32 measures three parameters: ambient or dry bulb temperature (DB), natural wet bulb temperature (WB), and globe temperature (G).
In addition to the WBGT, the QUESTemp°32 measures relative humidity (RH) and computes the Heat Index (HI) or Humidex. The QUESTemp°32, using inputs on the side of the instrument, has the ability to connect to two additional sensor arrays for monitoring up to three locations simultaneously.
Wet Bulb Globe Temperature
The WBGT is a weighted average of the three temperature sensors using the following formulas:
WBGT (indoor) = 0.7WB + 0.3G (denoted as “WBGTi” on the display)
WBGT (outdoor) = 0.7WB + 0.2G + 0.1DB (denoted as “WBGTo” on the display)
NOTE: The resulting WBGT can be compared to indices of
Heat Index / Humidex
The Heat Index is determined using the dry bulb temperature and relative humidity. Based upon charts available from the U.S. National Weather Service, Heat Index represents how an average person feels relative to climate conditions. For a constant temperature, if the humidity rises, so does the heat index.
The Heat Index is defined over a temperature range of 70°F - 120°F (21°C - 49°C) and a relative humidity range of 30% - 99%. Outside of this range, the instrument will show dashes in the display for the Heat Index.
The Humidex is used primarily in Canada and is very similar to the Heat Index. The values are slightly different. The Humidex is defined over a temperature range of 70°F - 109°F (21°C - 43°C) and a relative humidity range of 20% - 99%. Outside of this range, the instrument will show dashes in the display for the Humidex.