Tri-sensor Calculation and Remote Cable
Tri-sensor Weighted Average
7
Tri-sensor Calculation and Remote Cable
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 60
C.
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
36 always assigns the top sensor bar the double weighting. This calculation
is shown if a WBGT display has been selected and if three sensor sets are connected.
Removable sensor bar
RS-232
Tri-sensor calc.
Sensor
Bars 2 & 3
Figure 1-5: Ports identified
Tri-sensor
Calculation and
Remote Cable
