Analytical Industries GPR-1800 AIS ATEX Trace PPM Oxygen Analyzer - Manual (Page 32)

Advanced Instruments Inc.
32
Symptom Possible Cause Recommended Action
Response time slow
Air leak, dead legs, distance of sample line,
low flow rate, volume of optional filters and
scrubbers
Leak test (above), reduce dead volume or increase
flow rate
O
2
reading doesn’t
agree to expected O
2
values
Pressure and temperature of the sample is
different than span gas
Abnormality in gas
Calibrate the transmitter (calibrate at pressure and
temperature of sample)
Qualify the gas (use a portable transmitter)
Erratic O
2
reading
or
No O
2
reading
Change in sample pressure
Dirty electrical contacts in upper section of
sensor housing
Corroded solder joints on sensor PCB from
corrosive sample or electrolyte leakage from
sensor
Corroded spring loaded contact in upper
section of sensor housing from liquid in
sample or electrolyte leakage from sensor
Liquid covering sensing area
Improper sensor selection
Presence of interference gases
Unauthorized maintenance
Sensor nearing end of life
Sensors without PCB use mV setting.
Calibrate the transmitter (calibrate at pressure and
temperature of sample)
Clean contacts with alcohol (minimize exposure time
of MS sensor to ambient air to extent possible)
Replace sensor and return sensor to the factory for
warranty determination
Upper section of sensor housing: Clean contacts
with alcohol, flow sample or zero gas for 2-3 hours
to flush sample system and sensor housing
Sensor: Replace if leaking and return it to the
factory for warranty determination
Wipe with alcohol and lint free towel or flow sample
or zero gas for 2-3 hours to flush
Replace GPR/PSR sensor with XLT sensor when CO
2
or acid gases are present. Consult factory.
Replace sensor and install scrubber
Consult factory.
Replace sensor
Erratic O
2
reading
or
Negative O
2
reading
or
No O
2
reading
accompanied by
electrolyte leakage
Pressurizing the sensor by flowing gas to the
sensor with the vent restricted or SHUT OFF
valve closed and suddenly removing the
restriction draws a vacuum on the sensor
or
partially opening the valves upstream of the
transmitter when using a pump downstream
of the transmitter to draw sample from a
process at atmospheric pressure or a slight
vacuum. Placing a vacuum on the sensor in
excess 4” of water column is strongly
discouraged.
A premature adjustment of the ZERO OFFSET
potentiometer is a common problem
Zero the transmitter. If not successful replace the
sensor
Avoid drawing a vacuum on the sensor, a
pressurized sensor may not leak but still produce
negative readings.
From MAIN MENU select DEFAULT ZERO