Hach-Lange ORBISPHERE 31xxx Installation and Maintenance - Manual (Page 38)

36
Troubleshooting
6.3 Ozone sensor
When the O
3
sensor has been properly calibrated using the ORBISPHERE measuring
instrument, the sensor has to settle down for up to 24 hours when used in very low O
3
concentration conditions.
Table 10 Troubleshooting - Ozone sensor
Problem Probable Cause Possible Solution
Sensor won't calibrate,
even after thorough
servicing.
Repeated calibrations go beyond
"expected limits" of instrument.
MOCA 3600 only:
Select membrane from
"Options/Membrane" menu. Then,
calibrate the sensor.
O
3
sensor cleaned with HNO
3
Instrument internal barometric
pressure sensor needs
calibration. Calibrate "Barom. Pressure" menu.
Check against a certified barometer. Do
not correct for sea level !
Wet membrane interface. Wipe dry with a tissue and re-calibrate.
"0000" O
3
levels
displayed.
Wrong reading scale "XXXX"
selected for display unit.
Change reading scale by selecting
"X.XXX, XX.XX or XXX.X" from
"Options/Display Units" menu.
Unexpected/incorrect
dissolved O
3
reading.
High residual current.
If concentration is significantly higher
than low limit, try a sensor service.
Insufficient flow rate.
Regulate flow equivalent to membrane
specified levels.
Length of sample line allows O
3
time to react.
Reduce length of sample tubing.
Doesn't match lab samples.
Take samples at close proximity to
sensor.