Ph Calibration; Ph Calibration Procedure - Hach 8362sc User Manual

4.7 pH Calibration

4.7.1 pH Calibration Procedure

DANGER
Handling chemical samples, standards, and reagents can be dangerous. Review the
necessary Material Safety Data Sheets and become familiar with all safety
procedures before handling any chemicals.
The manufacturer offers one and two point automatic and manual calibrations for pH. An
automatic calibration identifies the buffer table corresponding to the chosen buffer and
automatically calibrates the probe after it stabilizes. A manual calibration is performed by
placing the pH sensor in any buffer or sample with a known value and then entering that
known value into the controller.
The value of the sample used in the manual calibration may be determined by laboratory
analysis or comparison reading.
For best results with a new sensor, allow sample to flow through the measurement
chamber at least 10 hours before calibrating. For precise calibration of the pH electrode,
the two point calibration method is required. The manufacturer recommends using a pH 4
and pH 7 buffer. The pH 7 buffer is required for a first standardization and pH 4 (or pH 10)
buffer solution is required to calibrate the electrode slope. See
buffer information. Use the buffers as follows:
1. Holding the flow chamber nut in position, unscrew the flow chamber. See
2. Empty the water from the flow chamber and rinse with demineralized water.
3. Rinse the electrodes with demineralized water.
4. Fill the flow chamber with the pH 7 buffer and reinstall. Always use fresh buffers.
5. Calibrate the first point following the
page 25.
6. Remove the flow chamber, empty the first buffer and rinse the flow chamber and
electrodes with demineralized water.
7. Fill the flow chamber with the pH 4 (or pH 10) buffer and reinstall.
8. Calibrate the second point following the
page 25.
9. Remove the flow chamber, empty the second buffer and rinse the flow chamber and
electrodes with demineralized water. Reinstall the flow chamber.
10. Turn on the sample stream to the flow of 100–300 mL/min (100–300 cc/min). Allow the
sample to flow through the assembly for a minimum of one hour.
11. Using a qualified standard meter do an overflow method sample measurement, see
Figure 8 on page 31.
12. Compare this reading with the reading on the controller. If the reading is different, do a
single point sample calibration on the controller so that it reads the same as the
standard meter.
section 4.7.2
Two Point Automatic Calibration Method on
Two Point Automatic Calibration Method on
sc100 Operation
for additional
Figure 7.
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