pH and ORP sensors are sensitive electrochemical electrodes. Many field problems come from dry storage, damaged glass bulbs, contaminated platinum surfaces, wrong buffer selection or bubbles inside the bulb.

Short Answer

Store pH and ORP electrodes wet in 3 mol/L KCl solution when they will not be used for a long time. Use buffer solutions close to the target measurement range, clean before and after measurement, remove bubbles, and reactivate slow electrodes with the recommended acid and KCl soaking process.

Choose Calibration Buffers Close to the Application

For pH sensors, pH 6.86 is commonly used for zero-point calibration. For acidic applications, pH 4.00 can be used for slope calibration. For alkaline applications, pH 9.18 is more suitable. Choosing a buffer close to the target water improves practical accuracy.

For ORP sensors, standard solutions such as 86 mV, 256 mV or -40 mV may be used depending on the calibration requirement.

Do Not Let the Electrode Dry Out

Long-term dry storage can damage electrode performance and slow down the response. When not used for a long time, place the electrode in a protective cap containing 3 mol/L potassium chloride solution. For pH sensors, do not store the electrode dry.

Avoid prolonged immersion in distilled water. Distilled water can disturb the electrode condition and is not a proper long-term storage solution.

Cleaning and Slow Response Recovery

Clean the electrode with deionized water before and after measurement. For viscous samples, rinse carefully to remove solvents or residues. If a pH or ORP electrode has been used for a long time and becomes slow or inaccurate, soak the probe in 0.1 mol/L HCl solution for 24 hours, then soak it in 3 mol/L KCl solution for 2 hours.

For ORP electrodes with dirt on the platinum surface, toothpaste can be used to gently polish the platinum surface until it becomes shiny. Do this gently and avoid damaging other parts of the sensor.

Handling Tips Customers Often Miss

The glass bulb at the pH electrode tip must not touch hard objects. Any scratch or breakage can make the electrode fail. Before measurement, remove bubbles inside the glass bulb. During measurement, stir the electrode in the sample and then let it stand so the response can stabilize.

Cable protection is also important. Do not tension the cable or let non-waterproofed terminals enter water.

Related YexSensor PDF Guides

For calibration commands and model-specific handling notes, see the Water Quality Sensor Calibration and Usage Precautions PDF and the Water Quality Sensor Usage and Maintenance Instructions PDF.

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