MSA TG5000, Operating Manual

Page: 52 / 75

52
Calibration
5.3 Calibration Frequency for XCell Sensors with TruCal and Diffusion Supervision
(H
2
S & CO only)
Sensors with TruCal technology will adjust sensitivity without any manual intervention or calibra-
tion, unless called for by the sensor. If the adjusted sensitivity from TruCal deviates too far from
the last gas calibration sensitivity, the sensor will recommend or, in extreme cases, require a cali-
bration. When a calibration is recommended, the transmitter LED status indicators slowly pulse
green. Users can also enable a Calibration Alert function that will send a milli-amp signal on the
analog output to the control room when a calibration is recommended. When a calibration is
required, the status LEDs will flash yellow and the transmitter will go into a Calibration Required
Fault. With Diffusion Supervision enabled, the sensors also actively monitor the sensor inlet for
Obstructions.
With these two features, the time between calibrations can be extended up to 365 days. Actual
TruCal sensor performance will depend on the application, background gas exposure, and envi-
ronment. To validate XCell sensors with TruCal, it is recommended that users follow their regular
calibration cycle and record the “as found” and “as left” values, tracking the percent adjustment
over time. Once a baseline is established, the calibration intervals can be extended until the
percent adjustment is greater than the expected accuracy of the sensor.
5.4 Calibration Frequency for XCell Sensors with TruCal without Diffusion Supervision
(H
2
S & CO only)
Sensors with TruCal technology will adjust sensitivity without any manual intervention or calibra-
tion, unless called for by the sensor. If the adjusted sensitivity from TruCal deviates too far from
the last gas calibration sensitivity, the sensor will recommend or, in extreme cases, require a cali-
bration. When a calibration is recommended, the transmitter LED status indicators slowly pulse
green. Users can also enable a Calibration Alert function that will send a milli-amp signal on the
analog output to the control room when a calibration is recommended. When a calibration is
required, the status LEDs will flash yellow and the transmitter will go into a Calibration Required
Fault. Without Diffusion Supervision, regular calibration of the sensor must still be conducted to
confirm the sensor inlet is not obstructed.
Actual TruCal sensor performance will depend on the application, background gas exposure, and
environment. To validate XCell sensors with TruCal, it is recommended that users follow their
regular calibration cycle and record the “as found” and “as left” values, tracking the percent adjust-
ment over time. Once a baseline is established, the calibration intervals can be extended until the
percent adjustment is greater than the expected accuracy of the sensor.
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US