Hanna Instruments HI 4221 - Manual (Page 42)

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• Unrecognized buffer. Please check the buffer or the buffer list (for Semiautomatic and Automatic buffer entry
type): this message appears if the current buffer value is not close to any of the buffers from the buffer list/group.
Check if the current buffer is present in the buffer list or the appropriate buffer group was selected.
• The current buffer was already calibrated. Press to recalibrate in this point, or change
the buffer: this message appears when calibration is performed in one of the previous calibrated buffers.
Follow displayed instructions.
pppppH MEASUREMENTS H MEASUREMENTS H MEASUREMENTS H MEASUREMENTS H MEASUREMENTS
Make sure the instrument has been calibrated before taking pH measurements.
DIRECT MEASUREMENT
To measure the pH of a sample using the Direct reading mode:
• Press
and then to select pH Measure mode
(for the selected channel – HI 4222 only).
• Select the Direct reading mode (see pH Setup for details, page 20).
• Submerge the electrode tip and the temperature probe
approximately 4 cm (1½”) into the sample to be tested.
Allow time for the electrode to stabilize.
• The measured pH value will be displayed on the LCD, together
with a short GLP information or “Not Calibrated” message if
no pH calibration was performed.
Note: If the reading is out of range, “-----” will be displayed
on the LCD.
DIRECT / AUTOHOLD MEASUREMENT
To measure pH of a sample using the Direct/AutoHold reading mode:
• Press
and then to select pH Measure mode
(for the selected channel – HI 4222 only).
• Select the Direct/AutoHold reading mode (see pH Setup for
details, page 20).
• Submerge the electrode tip and the temperature probe
approximately 4 cm (1½”) into the sample to be tested.
Allow time for the electrode to stabilize.
• The measured pH value will be displayed on the LCD. If pressing
, the “AutoHold” indicator will start blinking on the LCD
until the stability criterion is reached. The pH value will be
frozen on the LCD, along with “AutoHold” indicator.