5
Sensors
Sensors
About the sensor bar
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.) 
Serial number and sensor bar number label
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. | A | B C | |||
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A. Globe thermometer |
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B. Relative humidity sensor |
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C. Dry bulb thermometer |
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