20
Relation between pH value and temperature
When performing calibration, set the pH value according to the temperature of the standard solution
as follows;
Standard solution
Name of solution
Temp.
pH value
Temp.
pH value
pH 4
Phthalate solution
0
℃
4.00
30
℃
4.02
5
℃
4.00
35
℃
4.02
10
℃
4.00
40
℃
4.04
15
℃
4.00
45
℃
4.05
20
℃
4.00
50
℃
4.06
25
℃
4.01
-
-
pH 7
Neutral
phosphate solution
0
℃
6.98
30
℃
6.85
5
℃
6.95
35
℃
6.84
10
℃
6.92
40
℃
6.84
15
℃
6.90
45
℃
6.83
20
℃
6.88
50
℃
6.83
25
℃
6.86
-
-
pH 10
Carbonate solution
0
℃
10.32
30
℃
9.97
5
℃
10.24
35
℃
9.92
10
℃
10.18
40
℃
9.89
15
℃
10.12
45
℃
9.86
20
℃
10.06
50
℃
9.83
25
℃
10.01
-
-
JIS Z 8802-2011
Measuring procedure
(1) Connect the sensor probe to the main unit. When the PHP-31 sensor, which is capable of
measuring both pH and temperature, is used, connect both the BNC plug (pH) and the diode plug
(temperature).
(2) Press the PWR key to turn on the unit. The whole LCD lights up for approximately three seconds.
The unit enters the measurement mode.
(3) Remove the glass electrode protection bottle from the sensor probe.
(4) Immerse the sensor probe at least 3 cm deep into the material to be measured.
(5) Read the pH value when the reading becomes stable.
(6) To display the voltage, press the pH/mV key. The voltage detected by the sensor probe is
displayed.
(7) To end the measurement, press the PWR key to turn off the unit.
Wash the glass electrode with water (distilled, pure or tap water), install the glass electrode
protection bottle and store the instrument.
Note: For how to install or remove the glass electrode protection bottle, refer to "Glass electrode
protection bottle".