Xylem Oxi 1970i PORTABLE DISSOLVED OXYGEN METERS - Manual (Page 50)

What to do if... Oxi 1970i
50 ba75691e01 01/2007
Error message
E7 E7 E7 E7
AR flashes
continuously
Measured value too low
Measured value too
high
Display
to to to to
Sensor symbol flashes
Cause Remedy
Membrane damaged
– Membrane damaged – Regenerate sensor
– Membrane head not screwed
on tight enough
– Screw membrane head tight
Cause Remedy
No stable measured value
– Membrane contaminated – Clean membrane
Cause Remedy
– Insufficient
flow
– Provide flow to the sensor
Cause Remedy
– High amount of dissolved
substances
– Correct solubility function
using the salinity equivalent
– Air bubbles bump on the
membrane with high velocity
– Avoid direct flow to the
membrane
– The carbon dioxide pressure is
too high (> 1 bar)
– Measuring not possible
Cause Remedy
– Time-out of the interface – Check the instrument
connected
Cause Remedy
– Calibration interval expired – Recalibrate the measuring
system