Endress+Hauser COS22D Einbauanleitung Seite 6

Maintenance of the sensor
2.2 Changing the electrolyte and/or the membrane body
The electrolyte is used up slowly during operation. This is caused by electrochemical substance
reactions. In de-energized state, no substance reactions take place, and the electrolyte is not used up.
The operating time of the electrolyte is shortened by diffusion of dissolved gases such as H
high concentrations of CO
The theoretical operating time of an electrolyte filling for use in air-saturated potable water (pO
mbar) at 25 ˚C (77 ˚F) is as follows:
• COS22D-*1 (standard sensor): >1.5 years
• COS22D-*3 (trace sensor): >3 months
CAUTION
!
The standard electrolyte is a strong irritant
Danger of severe skin and eye irritation
► Be absolutely certain to observe the corresponding workplace safety regulations.
► Wear protective clothing, gloves and goggles when handling the electrolyte.
► In case of eye contact: Remove contact lenses, flush eyes with water for a few minutes and contact
a doctor.
► In case of skin contact: Take off wet clothing immediately, wash the skin or take a shower.
Generally, the following applies:
• The membrane cap must be replaced if:
– It is damaged.
– It is stretched. This makes the produced sensor currents too small.
• Changing the electrolyte is mandatory if the membrane body is detached.
• Sensors operated close to the zero point consume hardly any chemical electrolyte. The electrolyte
does not have to be replaced for a long period.
• Sensors operated at high partial oxygen pressures (> 100 hPa) consume a significant amount of
electrolyte. The electrolyte has to be replaced frequently.
Removing the old membrane body
1. Remove the sensor from the medium.
2. Clean the outside of the sensor.
3. Hold the sensor vertically and unscrew the shaft sleeve.
The membrane body is either in the shaft sleeve or is still on the glass portion with the anode and
cathode.
4. Remove the membrane body.
To do so, use the supplied disassembly tool for the membrane body.
5. Decide:
a. Do you want to replace the membrane body and not use it again?
► Dispose of the electrolyte and the old membrane body.
b. Do you want to replace the electrolyte only and not replace the membrane body?
► Drain the membrane body and flush with potable water.
► Continue as for the new membrane body.
6
.
2
Oxymax COS22D
S, NH or
2 3
=210
2
Endress+Hauser