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About the sensor bar
5
Sensors
About the sensor bar
The sensor bar, on the QTº 44/46, is calibrated to its specific instrument and is not
interchangeable with other QTº 44/46. The instrument has a sensor bar label which
includes the serial number of the instrument and a sensor bar number. (This is
indicated in the diagram below.)
Figure 1-4: About sensor bar and serial number
Globe Thermometer
The globe thermometer (left position) gives an indication of the radiant heat
exposure on an individual due to either direct sunlight or hot objects in the
environment. This is accomplished by placing a temperature sensor inside a
blackened copper sphere and measuring the temperature rise. The WBGT index is
based on the response of a 6 inch diameter globe. The QUESTemp uses a 2 inch
diameter globe for a faster response time. The temperature of the 2 inch globe is
correlated to match that of a 6 inch globe.
Waterless Wetbulb Sensor and Relative Humidity Sensor
The relative humidity sensor (middle position) is used to calculate the Waterless
Wetbulb from a combination of dry bulb temperature, humidity and wind speed
measurements. The Waterless Wetbulb is used to calculate an estimated WBGT
value. (Please see “Waterless Wetbulb” on page 7 for more details.)
Dry Bulb Thermometer
The dry bulb thermometer (right position) measures the ambient air temperature.
This measurement is used in the outdoor WBGT calculation when a high solar
radiant heat load may be present. The series of white plates surrounding the
sensor shield it from radiant heat.
Figure 1-5: Sensors identified
A. Globe thermometer
B. Relative humidity sensor
C. Dry bulb thermometer
Sensors
A
B
C
Serial number and sensor bar number label