8
OXY 7
5. Maintenance of the probe DO7/3mt
If the instrument does not calibrate or reading does not stabilize, it is necessary to perform a maintenance
of the probe. For maintenance follow the following steps in order:
Replace the electrolyte
Clean the anode and the cathode
Replace the membrane cap
5.1 Replacing the electrolyte
1) Remove the membrane cap from the sensor, check that it is not punctured or damaged, if intact it
can be reused otherwise you have to replace it.
2) Wash the membrane and the sensitive part of the sensor with distilled water, remove any
remaining salt and dry with paper towels.
Be very careful when handling the sensor and the membrane. Falls, shocks or crushing can
damage the sensor.
3) Fill the membrane cap with electrolyte at half level and screw it on the sensor, stir gently.
Unscrew the membrane and empty it completely, this will eliminate any remaining traces of water
or dust.
4) Refill the membrane with electrolyte again, this time completely, and screw on the sensor making
sure that no air bubbles inside. A light leakage of electrolyte during the screwing of the membrane
ensures that inside there are no air bubbles.
5) Wash the probe and leave in distilled water for at least half an hour, to rehydrate the membrane.
Make a
Calibration of the oxygen sensor
.
If doesn’t work proceed with
Maintenance of the anode and
the cathode
.
5.2 Maintenance of the anode and the cathode
The sensitive part of the probe is composed of an anode and a cathode, the two elements are constructed
with precious metals. These metals, with time, can be passivated by decreasing the efficiency of the
probe, up to the point that the probe does not calibrate.
In this case, remove the membrane and remove the passivation with super fine sandpaper, gently
scratching the metal parts, wash everything with distilled water and proceed with
Replacing the
electrolyte
.
Make a
Calibration of the oxygen sensor
. If doesn’t work proceed with
Replacing the membrane cap
.
5.3 Replacing the membrane cap
If the membrane has ripples or irregularities it must be replaced with a new one.
Remove the membrane and replace it with a new and intact one.
With the new membrane follow the procedure of
Replacing the electrolyte
.
If even after all these steps the probe does not calibrate then replace the probe.
