OxyGuard Light Duty pH Probes

The four types of light duty pH probe - flow-through, thread mount, submersion and immersion, all have sealed combination electrodes. They are built up in the same manner, and should be maintained in the same manner.

Regular maintenance is limited to keeping the electrode clean - as with all pH probes. Soapy water works wonders, but in stubborn cases you can use a dilute bleach (sodium hypochlorite) solution. Unstable readings are usually caused by a dirty electrode.

Sealed combination electrodes have a long, but finite lifetime, and need replacing when they no longer can be calibrated up to the correct values. When replacing electrodes start by cleaning and drying the whole probe. Make sure that no moisture will be able to reach the top of the new electrode or the connector in the upper part that mates with it - i.e. do not change electrodes outdoors in rainy weather or in other wet environments.

When you dismantle the probe, as shown in the illustration overleaf, carefully note the exact position of any O-rings and gaskets sealing the electrode top, and reassemble in a similar manner. Remember to calibrate the new electrode.

Electrode Replacement

OxyGuard pH probes are not sensitive to moisture when they are assembled, but electrode exchange MUST take place in dry conditions - the electrode top and connector inside the preamplifier must be completely dry when put together.