wtw Oxi 330i Operating Manual page 48

What to do if...
Error message E7
AR flashes
continuously
Measured value too low
Measured value too
Display
Probe symbol flashes
48
E7 E7 E7
Cause
Membrane damaged
– Membrane damaged
– Membrane head not screwed on
tight enough
Cause
No stable measured value
– Membrane contaminated
Cause
– Insufficient
flow
Cause
high
– High amount of dissolved
substances
– Air bubbles bump on the
membrane with high velocity
– The carbon dioxide pressure
is too high (> 1 bar)
Cause
to to to to
– Time-out of the interface
Cause
– Calibration interval expired
Remedy
– Regenerate probe
– Screw membrane head tight
Remedy
– Clean membrane
Remedy
– Provide flow to the probe
Remedy
– Correct solubility function using
the salinity equivalent
– Avoid direct flow to the
membrane
– Measuring not possible
Remedy
– Check the instrument that is
connected
Remedy
– Recalibrate the measuring
system
Oxi 330i/340i