Two-Points Calibration; Process Ph Calibration - Hanna Instruments PCA 311 Instruction Manual

TWO-POINTS CALIBRATION

Note:

PROCESS pH CALIBRATION

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• The analyzer prompts for the second buffer selection, and
displays the message "Select buffer pH... or press SET for
one point cal.".
Pressing "SET" key will end the one point calibration procedure.
• To perform a two-points pH calibration follow the steps de-
scribed at one-point calibration until the analyzer displays the
message: "Select buffer pH... or press SET for one point cal.".
• Immerse the pH electrode into the second buffer
solution (e.g. pH 4.01) until the metal ring is
immersed, then stir gently.
• Press "UP" or "DOWN" arrow keys to select
the second buffer from the list to continue the
calibration and confirm with "CFM".
The difference between the first and second buffer must be
more than 1 pH unit in order to assure the calibration accu-
racy. Calibration using 7.01 and 6.86 pH or 10.01 and 9.18
pH is not allowed.
• The analyzer checks for readings stability. During this period,
the "Wait for stabilize" message is displayed.
• When the reading becomes stable, the instrument checks if
the calculated slope is between 47.3 and 68 mV/pH. If the
value is not within this range, the message "Wrong calib.
values" is displayed. In this case it is necessary to perform a
cleaning procedure (see "Electrode conditioning and
maintenance" section) or to replace the probe.
• If the value is accepted, the analyzer displays "Stable... press
CFM".
Pressing CFM, the two point calibration is completed.
The PCA 321 and PCA 331 has the possibility to calibrate the
pH probe without using buffers and without dismount the
probe. For doing this calibration, a reference pH-meter must
be used. To complete the process calibration, follow the steps:
• Pour a quantity of sample in a beaker. Use the sample of the
measured liquid directly from the drain port of the measuring
cell (#11) by opening it's valve (#10) to do this as described
in the Calibration Procedure chapter.
• Place the pH probe of the reference meter in the beaker and
stir gently.
Probe
pH 4.01