To test the sensor response using test gas from a tank, remove the two retaining screws and
open the lid. Then apply gas to the sensor. The concentration on the 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 detector
housing. Allow 20 to 30 minutes for the test gas to completely replace the air inside the
detector housing. If the test gas has the required concentration, the detector should respond
by displaying a concentration and activating the appropriate ventilation component(s).
Because of the uncontrolled conditions in the test area, the detector may not indicate a
concentration equal to that of the test gas. However, sufficient response can be obtained to
determine that the detector is working.
Brasch Environmental Technologies recommends testing the detector 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.
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.
Please refer to figures 16 and 17 in the appendix of this manual while removing and installing
the sensor board assembly.
To replace a local sensor board assembly, remove the two retaining screws in the lid.
Carefully open the cover and slide the switch to the “OFF” position before unplugging the
sensor board from the control board. Then, remove the three screws securing the sensor
board to the standoffs. Lastly, pinch the locking standoff to extract the sensor board. If
replacing a second local sensor board, repeat this process. Set the old sensor board(s) aside.
After making sure that all jumpers and switches on the new sensor board match the old sensor
board, place the new sensor board onto the standoffs and return the three screws. Plug the
cable back into the board exactly as it was before. Repeat this process if replacing a second
local sensor board. Ensure that all boards are securely fixed to the support plate and
standoffs. Return the switch to the “ON” position and close the lid. Firmly tighten the two
retaining screws. Finally, check for proper operation. See “Applying Power for the First Time”
on page 18 and “Using the Self-Test Feature” on page 19.
IOM01
Rev 1.0 – December 22, 2020 31
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