Page | 61
Aeroqual AQM60 User Guide
8.
Troubleshooting
8.1.
AQM60 Basics
Symptom
Possible Cause
Fault isolation/Solution
Gas sensor readings
incorrect
Insufficient warm up
Incorrect zero calibration
Incorrect span calibration
Sensor module leaking
Sensor pump failed
Allow the sensors to fully warm up
after power down. This may take 2-3
hours.
Repeat zero calibration with clean air.
Check media in Gas Treatment
module.
Perform span check.
Check for leaks
Measure flow. If pump has failed
replace.
NO
2
sensor reading very high
Incorrect zero calibration
O
3
Scrubber failed
Repeat zero calibration with clean air.
Check media in Gas Treatment
module.
Expose the NO
2
sensor with 0.1 ppm
of O
3
. If the response is large (>0.5
ppm) then the scrubber has failed.
Replace.
Gas Sensor readings noisy or
unstable
Leaks
Particle filter
Leaks dilute the sample stream and
can cause low span readings and
incorrect zero readings. Perform a
leak test.
Replace if dirty.
“NR” or “9999” in Data table
(No response)
Occasional NR or “9999” in
Data Table
F
requent “9999”
No Response from Sensor
module. Not connected
correctly
Bus cable
Computer too slow
RF noise in environment
RS485 bus cable is faulty
Module RS485 chip faulty
RF noise in environment
Check that the electrical connectors
on the sensor modules are firmly
connected.
Check RS485 bus cable continuity.
Test with a faster computer.
Try to reduce RF noise.
Replace bus cable.
Remove one module at a time to
identify faulty module and then
replace.
Try to reduce RF noise