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.

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.

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.

Electrolyte membrane

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