YOKOGAWA PH72, Руководство пользователя

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IM 12B03D02-01E
4-1
4 . Calibration
4. Calibration
Calibration using standard solutions means to measure the pH value of a certified
standard solution and to adjust the pH meter so it reads the same value as
the certified value of the standard solution. The PH72 meter can be calibrated
automatically or manually.
The PH72 meter must be calibrated before measurement if:
• it has been stored for a long period;
• the electrode has been cleaned; or
• otherwise necessary.
Precautions
(1) Use certified standard solutions. Using deteriorated standard solutions will result
in inaccurate calibration. Standard solutions are available as spare parts (see
Section 1.8).
Pour a portion of the standard solution into a calibration bottle (supplied) and use
for calibration. Do not reuse the portion. Discard it and use a fresh portion for
another calibration.
(2) Do not press CAL key unless calibration is needed. Otherwise, saved
calibration results may be changed.
(3) Temperature of standard solutions should be close to that of measuring solutions
in normal condition. The gap of temperature between those solutions may result
in inaccurate measurement.
Before Calibration
The following should be checked and set before calibration.
(1) Contamination of the sensor
Make sure that no dirt or deposits are present on the sensor.
(2) Temperature setting
When using a sensor without a built-in temperature element, i.e., a needle type
or test tube size pH sensor, the temperature of a standard solution to be used
should be set into the meter (refer to Section 5.3 (2), “Manual temperature
setting (M.tP) panel”).
(3) Battery condition
Check the battery condition indicator for remaining life. If the indicator is flashing,
calibration cannot be performed. Replace the batteries (refer to Section 2.1,
“Installing the Batteries”).
Error Messages during Calibration
If the meter detects an abnormality during calibration, , , or
may be displayed. In such a case take corrective actions referring to Chapter
7, “Troubleshooting.”