15
3. When the “7” stops blinking, the calibration
can be confirmed. Wait 30 seconds and press
the CON key to confirm the first buffer. If
wrong solution or electrode has been used or
if the buffer is out of specifications the “7” symbol will not stop
blinking to alert the user.
4. If everything is satisfactory the instrument will print a set of data
(see page 16) and will expect the second buffer at pH 4.01 or pH
10.01.
Note
: If only one a single point calibration is
required, press CAL to leave the calibra-
tion mode. However, it is always better
to proceed as follows with two point
calibration.
5. If you are measuring acid samples (pH 7 or less) use the pH 4.01
buffer (HI7004). For alkaline solutions (pH 7 or more) use pH
10.01 (HI7010) buffer.
6. Rinse the electrode and the temperature
probe with clean water or some pH4.01 (or
10.01) solution. Dip the bottom 4 cm (1½")
of the electrode in a beaker containing the
second buffer. The HI92240 will recognize
the buffer solution and automatically
switches to the appropriate value shown
by the blinking “4” or “10” symbol.
7. When “4” (or “10”) stops blinking, indicat-
ing that the electrode has stabilized, wait 30
seconds and then press CON again to confirm
the second calibration point.
8. A new set of data will be printed (see page
16), the buffer reference disappears from the secondary display
and the meter is calibrated and ready to use.
9. If you cannot complete the calibration, check your electrode by
following the conditioning and the maintenance procedure on
page 29 and repeat the calibration. The pH electrode might
have to be replaced if calibration cannot be successfully com-
pleted.
CON
CAL
4 cm
(1½")
HI 7004
CON
