8 Remote, Sensors 2 and 3
Tri-Sensor Weighted Average
Remote, Sensors 2 and 3
The top sensor bar (sensor 1) may be removed from the instrument and used through a
remote cable. Shelter the instrument and remote the sensor bar if the measured
environment is expecting heavy rain or if temperatures are above 60C.
The sensor 2 and sensor 3 jacks on the side of the instrument allow simultaneous
monitoring of up to three sensor arrays using connecting cables.
Cable lengths of up to two hundred feet (61 meters) may be used without a decrease in
accuracy provided the environment does not contain strong electromagnetic fields.
The data from these arrays may be viewed separately or combined into a weighted
average WBGT reading per ISO 7243. Change the displayed sensor bar by pressing
and releasing the enter key. The upper right corner of the display shows the current
sensor bar. 1 refers to the top sensor bar, 2 and 3 are labeled on the side of the unit, W
indicates the weighted average which only appears if a WBGT is displayed and all three
of the sensor bars are attached.
Tri-Sensor Weighted Average
Per the recommendations outlined in ISO 7243:2017, when the temperature in the
space surrounding a worker is not uniform, it is necessary to determine the WBGT
index at three heights corresponding to the worker's ankles, abdomen and head and
perform a weighted average on those values. It is computed using the formula:
WBGTw = (WBGT
head
+ (2 x WBGT
abdomen
) + WBGT
ankles
)/4
The QUESTemp° 32 always assigns the top sensor bar the double weighting. This
calculation is shown if a WBGT display has been selected and if 3 sensor sets are
connected.
Operational Check
A verification module, model 054-544, may be used to check the operation of the
QUESTemp. Remove the top sensor bar and plug the verification module into the top of
the unit. With the QUESTemp set to read in degrees Celsius, verify that the displayed
readings match those printed on the module within ±0.5C.
If the readings are not within the ±0.5C tolerance, then have the unit serviced and
calibrated.