YOKOGAWA PH71, User Manual

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IM 12B03D01-01E
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 PH71 meter can be calibrated automatically or
manually.
The PH71 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.
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.”)