Hanna Instruments HI 902 Color, Quick Start Manual

Page: 119 / 248

7-13
pH, mV & ISE MODE
Three buffer entry types are available: Automatic, Semiautomatic and Manual Selection (see
section
7.1.2.1 Buffer Entry Type).
To begin calibration:
• Press . If the instrument was calibrated before and the calibration was not
cleared, the old calibration can be cleared by pressing .
Note: It is very important to clear calibration history when a new electrode is used.
• Immerse the pH electrode and the temperature probe approximately 4 cm (1.5")
into a buffer solution and stir gently. The temperature probe should be close to the
pH electrode.
• Select the pH calibration buffer value with or .
• Press to update the calibration. Once the reading has stabilized, the calibration
buffer will be added to the Calibrated Buffers section.
• Rinse the pH electrode and the temperature probe, then immerse them into the next
buffer solution and follow the above procedure or press
to exit the procedure.
Notes: The new calibration points will replace old ones if the difference between them is
+/- 0.2 pH. Buffers used in older calibrations will not have a solid background.
If calibrating with a standard buffer in MTC mode, the pH value and temperature can
be modified by pressing . The values can be adjusted using the numeric keys.
Press to save the new values.
buffer solution: one for rinsing the electrode and one for calibration. If you are measuring in
the acidic range, use pH 7.01 or 6.86 as the first buffer and pH 4.01/3.00 or 1.68 as the
second buffer. If you are measuring in the alkaline range, use pH 7.01 or 6.86 as the first
buffer and pH 10.01/9.18 or 12.45 as the second buffer.
For extended range measurements (acidic and alkaline), perform a five-point calibration by
selecting five buffers across the entire pH range.
CALIBRATION PROCEDURE
During calibration, the user has a choice of 8 standard buffers: pH 1.68, 3.00, 4.01, 6.86,
7.01, 9.18, 10.01, 12.45 and up to 5 custom buffers.
For accurate measurements it is recommended to perform a five-point calibration. However, at
least a two-point calibration is suggested. For pH titrations the selected buffers should bracket
your endpoint (e.g.: if your endpoint value is at 8.5, use 7.01 and 9.18 for calibration).
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