Hanna Instruments HI 9812-5N - Manual (Page 8)

8
For greatest accuracy, frequent calibration of the instrument is
recommended. The instrument should be recalibrated for pH:
a) Whenever the electrode is replaced.
b) At least once a month.
c) After testing aggressive chemicals.
d) Where extreme accuracy is required.
PREPARATION
Pour small quantities of pH 7.01 (
HI 7007) or pH 4.01 (HI 7004)
or pH 10.01 ( HI 7010) solution into a clean beaker.
To obtain accurate readings, use pH 7.01 ( HI 7007) if you are going
to measure neutral or close to neutral samples, pH 4.01 ( HI 7004)
if you are going to measure acidic samples or pH 10.01 ( HI 7010)
for alkaline measurements.
If you need to calibrate to NBS standards, use pH 6.86 (
HI 7006)
instead of pH 7.01 and pH 9.18 ( HI 7009) instead of pH 10.01.
PROCEDURE
• Connect the probe and switch the meter on, then press the
pH
key to display pH measurement.
• Remove the protective cap from the probe, rinse and immerse it in
the buffer and stir gently. Wait a couple of minutes for the
reading to stabilize.
• Select the °C mode by pressing the °C
key and read the displayed value to
take the temperature of the buffer
solution, e.g. 10.0°C.
• Adjust the pH calibration knob until
the LCD shows the pH value at the
above temperature (see the pH versus
temperature chart).
• The pH calibration is now complete.
Notes: • The probe should be submerged approximately 4 cm
(1½") into the solution.
• If turning the knob the needed value can not be reached,
clean the probe (see the "Probe Maintenance" section). If
also after the probe cleaning the value can not be
reached, replace the probe.
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