Hach ORBISPHERE 31 Série Manuel D'utilisation Simplifié page 19

Problem
Shorter than expected sensor
operation in relatively high H
concentration.
Unexpected or inaccurate H
readings.
7.3 Ozone sensor
When the O sensor has been properly calibrated using the ORBISPHERE measuring instrument,
3
the sensor has to settle down for up to 24 hours when used in very low O
Problem
Sensor won't calibrate, even
after thorough servicing.
"0000" O levels displayed.
3
Unexpected or inaccurate
dissolved O readings.
3
Probable cause
High H concentrations require
2
more work from
2
electrochemical sensor.
2
High residual current.
Probable cause
Repeated calibrations go
beyond "expected limits" of
instrument.
Instrument internal barometric
pressure sensor needs
calibration.
Wet membrane interface.
Wrong reading scale "XXXX"
selected for display unit.
High residual current.
Insufficient flow rate.
Length of sample line allows O
time to react.
3
Doesn't match lab samples.
Possible solution
Shut off analyzer when not
needed.
If concentration is significantly
higher than low limit, try a
sensor service.
concentration conditions.
3
Possible solution
MOCA 3600 only: Select
membrane from
"Options/Membrane" menu.
Then, calibrate the sensor.
Calibrate internal barometer
against a certified barometer.
Do not correct for sea level !
Wipe dry with a tissue and re-
calibrate.
Change reading scale by
selecting "X.XXX, XX.XX or
XXX.X".
If concentration is significantly
higher than low limit, try a
sensor service.
Regulate flow equivalent to
membrane specified levels.
Reduce length of sample
tubing.
Take samples at close
proximity to sensor.
English 19