9
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.
e) Whenever the CAL CHECK test fails (
HI9813-6
only).
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.
Notes:
• The probe should be submerged approximately 4 cm (1½”)
into the solution. The thermometer has to be located close
to the probe.
• 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.
pH CALIBRATION