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CALIBRATION
10. CALIBRATION
10.1. pH CALIBRATION
The HI981412 provides a digital calibration at the push of a button. Calibrate the probe frequently
for improved accuracy. Also:
• before in-line or flow cell installation
• whenever the probe is replaced
• after periodic maintenance
Always use fresh calibration buffers and perform electrode maintenance prior to calibration
(see ELECTRODE CARE & MAINTENANCE section) .
Preparation
Pour the buffer solution into clean beakers. If possible, use plastic beakers to minimize any
EMC interferences. For accurate calibration and to minimize cross-contamination, use two beakers,
one for rinsing the probe and one for calibration.
User Calibration
One- or two-point calibration can be performed using one of the three standard buffer solutions: 4.01,
7.01 or 10.01pH.
When a two-point calibration is required, use 4.01 pH buffer as first calibration point.
Procedure
• Press CAL key to enter calibration mode.
• Place the electrode in chosen pH buffer solution.
• Press CAL key to save calibration point and return to measurement screen.
• Long press MENU key to exit without saving.
One-Point Calibration
• Press CAL key to enter calibration mode. “pH 7.01 USE” message is displayed as calibration point.
• Place the electrode in 4.01, 7.01 or10.01 pH buffer. The controller automatically recognizes the
buffer value.
• When the buffer is recognized, “RECOGNIZED” is scrolled at the bottom of the LCD display. “WAIT”
is displayed until the reading is stable and the calibration is accepted.
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