Calibration Guide: pH Meters (8680, 8681, 8682)

Summary: To ensure precision, these meters feature automatic buffer recognition for pH 4, 7, and 10. For the best results, a "3-point calibration" is recommended, always starting with the pH 7 buffer first.

Step 1: Preparation

Before beginning, ensure you have the following:

• Buffer Solutions: pH 7.0 (required first), then pH 4.0 and/or 10.0.
• Rinse Water: De-ionized (DI) water is preferred, though tap water may be used for rinsing.

Step 2: The Calibration Process

1. Power On: Press the power button to turn the meter on.
2. Submerge: Place the electrode into the pH 7 buffer solution.

3. Enter CAL Mode:

   • Press the CAL button.

   The display will briefly show "CA" (or "CAL" on the 8682) for one second, then begin flashing the recognized buffer value.

4. Stabilize: Hold the probe in the solution until the reading stabilizes.
5. Save: Once the value is stable and no keys are pressed, the meter will automatically display "SA" (Saved) and return to normal measurement mode.
6. Rinse: Rinse the electrode with DI or tap water before moving to the next buffer.
7. Repeat: Repeat these steps for pH 4.0 and pH 10.0 to complete the 3-point calibration.

Adjusting for Specific Buffer Values

Using the "HLD" Button:

If your specific buffer is not exactly 4.0, 7.0, or 10.0 (for example, a 4.01 pH solution), you can manually adjust the calibration point. While the meter is in CAL mode, press the HLD button to cycle the value within these ranges:

• 4.0 pH Range: Adjustable from 3.50 to 4.50
• 7.0 pH Range: Adjustable from 6.50 to 7.50
• 10.0 pH Range: Adjustable from 9.50 to 10.50

Troubleshooting Calibration Errors

If the meter cannot recognize the buffer or the probe is damaged, it will exit calibration mode automatically after 10 seconds.

Error Code	Model	Meaning / Solution
En	8680 / 8681	Calibration End/Error: The probe could not detect the buffer or the voltage is out of range. Check that your buffer is fresh and the probe is clean.
End	8682	Calibration End/Error: Same as above. Ensure the probe is fully submerged and the buffer solution is correct.

Electrode Maintenance

💡 Pro Tip for Longevity

Always rinse the probe with de-ionized water or tap water after every single measurement. This prevents cross-contamination and significantly extends the life of the sensitive pH electrode.