Calibration - Hanna Instruments HI9811-51 Instruction Manual

6. CALIBRATION

6.1. pH
For high accuracy, frequent calibrations are recommended.
Additionally, the pH range should be recalibrated:
• Whenever the electrode is replaced
• At least once a month
• After testing aggressive chemicals
Preparation
Recommended pH calibration standard buffers: pH 4.01, pH 6.86 (NIST),
pH 7.01, pH 9.18 (NIST), pH 10.01
Use pH 7.01 (HI7007) for neutral samples, pH 4.01(HI7004) for acidic
samples, pH 10.01 (HI7010) for alkaline samples.
Procedure
1. Connect the probe and turn the meter on.
2. Press the pH key to select pH measurement mode.
3. Remove the protective cap and rinse the probe.
4. Pour buffer solution into a clean beaker.
5. Immerse the tip of the probe 4 cm (1 1/2") in selected buffer and
wait a few minutes for the measurement to stabilize.
6. Press the temperature key (°C) to measure buffer solution
temperature. Take a note of the displayed value.
7. Rotate the calibration knob to adjust the pH value to match written
buffer solution temperature. The pH calibration is now complete.
(see pH VALUES AT VARIOUS TEMPERATURES section).
Note: If, when rotating the knob, required value cannot be reached,
the probe requires cleaning (see the PROBE MAINTENANCE section).
If the issue still persists, the probe requires replacement.
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