Hanna Instruments HI 2221 - Manual (Page 10)

10
PROCEDURE PROCEDURE PROCEDURE PROCEDURE PROCEDURE
Calibration can be performed at up to five points. For accurate
measurements a three point calibration is recommended. Calibration
can be performed using the seven memorized buffers:
• pH 1.68, 4.01, 6.86, 7.01, 9.18, 10.01 and 12.45.
FIVE-POINT CALIBRATION
FIVE-POINT CALIBRATION FIVE-POINT CALIBRATION FIVE-POINT CALIBRATION FIVE-POINT CALIBRATION
For most applications it is recommended that pH 7.01 or 6.86 buffers be
used as the first calibration point and pH 4.01 (for acidic samples) or pH
9.18/10.01 (for alkaline samples) as the second calibration point.
Note: The pH 12.45 buffer is not for general measurement; use only if
the sample is very alkaline to avoid sodium error.
• Submerse the pH electrode and the temperature probe approximately
3 cm (1¼”) into a buffer solution and stir gently. The temperature
probe should be close to the pH electrode.
• Press the CAL key. “CAL” and “pH” tags will be on, and the
“CLEAR CAL if new electrode” tag will blink.
• Press the CLR key if you are using a new electrode or want to clear
the calibration history. The instrument will display the “donE” message
for a few seconds.
• Press the CAL key, or wait a few seconds to continue.
It is very important to clear the calibration history when a new electrode
is used because all error and warning messages that appear during
calibration depend on the calibration history.
Note: • The “CLEAR CAL if new electrode” will only appear if the
instrument has been previously calibrated.
• The “CAL”, “pH” and “BUFFER” tags will appear and the
“7.01” buffer will be displayed on the secondary LCD.
• If necessary, press the ARROW keys to select a different buffer
value.
• The “ ” tag will blink until the reading has stabilized.
CLEAR CAL if new electrode
pH
CAL