Ph Calibration; Ph Values At Various Temperatures - Hanna Instruments HI 9811-5 Instruction Manual

pH CALIBRATION

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.
• Take the temperature of the buffer solution,
e.g. 10.0°C, as follow:
for HI 9811-0, with a ChecktempC (or an-
other accurate thermometer);
for HI 9811-5, 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 tempera-
ture chart).
• The pH calibration is now complete.
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Note: The probe should be submerged approximately 4 cm (1½") into the
solution. The ChecktempC thermometer has to be located close to
the probe.
Note: 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 VALUES AT VARIOUS TEMPERATURES

For temperature compensation during calibration, please refer to the
following chart.
TEMP
°C °F 4.01 6.86
0 32 4.01 6.98
5 41 4.00 6.95
10 50 4.00 6.92
15 59 4.00 6.90
20 68 4.00 6.88
25 77 4.01 6.86
30 86 4.02 6.85
35 95 4.03 6.84
40 104 4.04 6.84
45 113 4.05 6.83
50 122 4.06 6.83
55 131 4.07 6.84
60 140 4.09 6.84
65 149 4.11 6.85
70 158 4.12 6.85
For instance, if the buffer temperature is 25°C, the display should
show pH 4.0 or 7.0 or 10.0.
If the buffer temperature is 10°C, the display should show pH 4.0 or
7.0 or 10.1.
pH VALUES
7.01 9.18 10.01
7.13 9.46 10.32
7.10 9.39 10.24
7.07 9.33 10.18
7.04 9.27 10.12
7.03 9.22 10.06
7.01 9.18 10.01
7.00 9.14 9.96
6.99 9.10 9.92
6.98 9.07 9.88
6.98 9.04 9.85
6.98 9.01 9.82
6.98 8.99 9.79
6.98 8.97 9.77
6.99 8.95 9.76
6.99 8.93 9.75
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