Operational Guide
24
pH
Calibration
Note
: Custom buff er values can be adjusted ±1.00 pH around the set
value during calibration. When a custom buff er is displayed, the “C1” or “C2”
tag is displayed.
First Calibration Point
When performing a new calibration, or adding to an existing one, the user has
a choice of how the fi rst new calibration point will be treated in reference to
the existing calibration point. This is selected in SETUP by the option FIRST
CALIBRATION POINT. The two SETUP selectable options are “POINT” or “OFFSET”.
Point: A buff er value can be recalibrated and added to the previous calibration
set. The electrode slope of the other calibration points will be reevaluated with
the recalibrated buff er value.
Off set: The new buff er calibration point can create a constant off set to all
existing pH calibration data (existing calibration must have a minimum of two
pH buff ers)
.
Recalibrating a pH sensor or adding to an existing calibration is simple and
follows the PROCEDURE outlined on page 22.
Press
CAL
. Place sensor in desired buff er and select buff er from choices. When
sensor has equilibrated, the
CFM
tag will turn on and blink. Press the
CFM
key.
Press
CAL
to escape the calibration. Alternately continue calibrating in
additional buff ers. The latest calibration point will be added to the existing data.
GLP will refl ect the latest calibration data. Older calibration buff ers will be seen
as blinking buff ers.
Note
: Each time a buff er is confi rmed, the new
calibration data replaces the old data for the
corresponding buff er or for any buff er in the proximity
of ±0.2 pH. If the current buff er has no previous data
stored and the calibration has not used fi ve buff ers,
the current buff er is added to the existing calibration.
If the existing calibration is full, the instrument asks
which buff er to replace.
Note:
When using Standard mode, the user can choose if they want the display
to show the CONDITION and RESPONSE gauges on the display. These are part of
the Cal Check™ system and are selected in SETUP by the option INFORMATION.
The choice is ON or OFF.
Electrode Condition and Electrode Response Time
edge
pH
®
pH Calibration Check™ feature will assess electrode condition and
response time during each calibration and display it for the rest of the day.
The condition gauge shows the electrode’s condition that is based on the off set
and slope characteristics of the pH electrode at the time of calibration. The
response gauge is a function of the stabilization time between the fi rst and
second calibration buff ers, when calibration is performed between a pair of
4.01, 7.01, or 10.01 buff ers. These gauges refl ect the electrode’s performance
and should be expected to slowly decrease over the life of the electrode .
