8
For greatest accuracy, frequent calibration of the instrument is recom-
mended. 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 pH7.01 (
HI7007
) or pH4.01 (
HI7004
) or
pH10.01 (
HI7010
) solution into a clean beaker.
To obtain accurate readings, use pH7.01 (
HI7007
) if you are going
to measure neutral or close to neutral samples, pH4.01 (
HI7004
) if
you are going to measure acidic samples or pH10.01 (
HI7010
) for
alkaline measurements.
If you need to calibrate to NIST standards, use pH6.86 (
HI7006
)
instead of pH7.01 and pH9.18 (
HI7009
) instead of pH10.01.
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.
• Take the temperature of the buffer solution,
e.g. “
10.0 °C
”, as follow:
Select the °C mode and read the displayed
value.
• 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.
pH CALIBRATION
