Xylem MPP 350 - Manual (Page 22)

What to do if... MPP 350
22 ba75434e02 07/2005
6 What to do if...
6.1 Error symptoms of D.O. measurement
Error symptom Cause Remedy
No D.O. display – No connection between meter and
sensor
– D.O. module not mounted
properly
– Cable defective
– Check connection between meter
and sensor
– Check the plug-in connection,
clean the contacts as necessary
– Return the sensor
The sensor is in the air
and the display shows
0.0 mg/l or 0 % O
2
– No connection between meter and
sensor
– D.O. module not mounted
properly
– No electrolyte in the membrane
cap
– Cable defective
– Check connection between meter
and sensor
– Check the plug-in connection,
clean the contacts as necessary
– Replace and refill the membrane
cap (see section 5.3)
– Return the sensor
The sensor cannot be
calibrated – Contaminated membrane cap
– Electrolyte depleted
– Membrane damaged – Replace and refill the membrane
cap (see section 5.3)
Subsequently, wait for 30 to
50 min and recalibrate.
The sensor still cannot
be calibrated after
changing the electrolyte
and membrane cap – Contaminated electrodes or
sensor toxification
– Membrane cap not screwed on
tight enough
– Clean the electrodes (see
section 5.4)
– Screw membrane cap tighter
Incorrect temperature
display – The temperature sensor of the
conductivity measuring cell is not
immersed in the measuring
solution
– Temperature sensor defective
– Observe the minimum immersion
depth
– Return the sensor
Measured values implau-
sible – Incident flow insufficient – Move the sensor in the test
sample (stirr) or use the battery-
powered stirrer, BR MPP 350
Mechanical damage to
the sensor – Return the sensor