11
ONE-POINT CALIBRATION
For optimum accuracy it is always recommended to perform a two-
point calibration, but for a faster operation it is also possible to carry
out a single-point procedure.
Buffers at pH 7.01 or pH 6.86 (NIST) are normally the most
appropriate for this purpose, even though the meter can be calibrated
with any of the memorized calibration values.
After calibrating the first point (see above), press the CAL key to end
the calibration procedure.
Note:
With one-point calibration there is no Condition and only the
frame is shown. Calibration time-out is active.
CUSTOM BUFFER SELECTION
The meter also allows the user to calibrate with custom buffers.
To select a custom buffer press the CUSTOM BUF key while in calibration
mode. Use the arrow keys to set the desired value for C1 (the default
value is 7.00).
Note:
To increase the speed, keep pressed the UP or DOWN key.
Once the desired value is reached, the meter will continue
calibration as with memorized buffers.
Pressing again CUSTOM BUF, the meter
will select the second custom buffer. Pressing
CUSTOM BUF once again, the meter will
return to the standard buffers mode.
EXPIRED CALIBRATION
The instrument is provided with a real time clock (RTC), in order to
monitor the time elapsed since the last pH calibration.
The real time clock is reset every time the meter is calibrated and the
expired calibration status is triggered when the meter detects a
calibration time-out. The CAL tag will start blinking to warn the user
that the meter should be recalibrated.
The calibration time-out can be set (see Setup menu section on
page 14) from 0 (function disabled) to 14 days.
For example, if a 4 days time-out has been selected the meter will
issue the alarm exactly 4 days after the last calibration.
However, if at any moment the expiration value is changed (e.g. to
7 days), then the alarm will be immediately recalculated and appear
7 days after the last calibration.
18
PREPARATION PROCEDURE
Remove the electrode protective cap.
DO NOT BE ALARMED IF ANY SALT DEPOSITS ARE PRESENT. This is
normal with electrodes and they will disappear when rinsed with water.
During transport tiny bubbles of air may have formed inside the glass
bulb. The electrode cannot function properly under these conditions.
These bubbles can be removed by "shaking down" the electrode as you
would do with a glass thermometer.
If the bulb and/or junction are dry, soak the electrode in
HI 70300
Storage Solution for at least one hour.
ELECTRODE CONDITIONING & MAINTENANCE
Not present in gel electrodes.