To test the sensor response using test gas from a tank, loosen the four retaining screws and
remove the lid. Then apply gas to the sensor. The concentration on the control panel display
should reach 90% of the expected reading within 30 seconds. Allow approximately 5 minutes
to ensure 100% response. If the response time is too slow or the concentration displayed is
outside of acceptable tolerance, the sensor should be recalibrated.
Alternatively, seal the vents and let the gas flow through a flexible hose into the transmitter
housing. Allow 10 to 15 minutes for the test gas to completely replace the air inside the
transmitter housing. If the test gas has the required concentration, the control panel should
respond by displaying a concentration and activating the appropriate ventilation component(s).
Because of the uncontrolled conditions in the test area, the panel may not indicate a
concentration equal to that of the test gas. However, sufficient response can be obtained to
determine that the transmitter is working.
Brasch Environmental Technologies recommends testing the transmitters once every six
months to ensure proper response and accuracy.
Replacing the Sensor
The sensor’s useful lifetime depends greatly upon its operating conditions. Continuous
operation around large or numerous gas sources may shorten the sensor’s useful life. A
recommended recalibration date is recorded on the front panel label of each transmitter.
Because each sensor requires individual calibration, the sensor is replaced by installing a new,
factory-calibrated sensor board assembly. This procedure can be accomplished in the field.
The old sensor board assembly may be discarded.
To replace a sensor board assembly, disconnect any power sources from the sensor board.
Remove the four retaining screws in the cover and set the cover aside. Unplug any
connections to the sensor board and remove the four screws securing the sensor board to the
housing. Place the old sensor board aside. After making sure that all jumpers and switches
on the new sensor board match the old sensor board, place the new sensor board into the
housing. Replace the four screws to secure the sensor board to the housing and return and
connections to their original locations. Carefully replace the cover, making sure to align the
indicator LEDs. Firmly tighten the four cover retaining screws. Restore the sensor power
sources and check for proper operation.
IOM03
Rev 1.1 – May 18, 2021
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