Hanna Instruments HI 9811 User Manual

Page 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

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.

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