Electrolyte & Membrane Replacement for Polarographic DO Sensors
One of the most common maintenance tasks with polarographic DO sensors is replacement of the electrolyte and membrane cap.
Polarographic Sensor Membranes
Put the sensor in an upright position and carefully unscrew the membrane cartridge.
- OxyFerm FDA Membrane Kit Ref 237140
- OxyGold Membrane Kit Ref 237135
Carefully clean the tip of the glass body with a soft tissue.
Check the small O-ring above the glass body. Replace if damaged.
Electrolyte Replacement
Use the plastic pipette of the membrane kit to pipette approximately 1 to 1.2 ml of electrolyte into the new membrane cartridge.
- OxyFerm Electrolyte Ref 237118
- OxyGold B Electrolyte Ref 237138
- OxyGold G Electrolyte Ref 237139
Carefully screw the cartridge onto the sensor shaft. Any spillage of electrolyte should be rinsed away with water.
After completion of this procedure the sensor should be reconnected to the cable and normal polarization and calibration procedures should be followed.

Related Content
- Procedure for Polarographic DO sensor cathode replacement.
- Time to upgrade from Polarographic to Optical DO Measurement? See the comparison here.
- Visit our main Dissolved Oxygen Knowledge Base Page to see all articles.