User guide

I-E67-84-1B February,2002 6-4
One-Point Calibrate State
Due to variations in ionic strength between
the sensor reference and process liquid,
improved accuracy can be realized by
conducting a one-point calibration with the
sensor in its final location. Typically, the
analyzer is verified against an external
validation device using a grab sample. The
One-Point Calibrate State conducts an offset
adjustment on the sensor input.
Conduct a One-Point Calibration using Figure
6-2 as a reference and the following
procedure:
1) Select the 1PT.CAL in the Process Sensor
Calibrate State of Operation using the
SELECT Key.
2) Verify the process variable value using
an external instrument having the same
type of temperature compensation and a
grab sample.
3) Confirm the TB84PH Advantage Series
analyzer displayed reading is STABL?
(i.e., stable) using either the YES or NO
Key. If the NO Key is pressed, the
analyzer will return to the Process
Sensor Calibrate State. For an unstable
condition, conduct one or more of the
following steps:
a) Wait until process liquid
composition stabilizes,
b) Check to see if the TB84
Advantage Series analyzer has
detected a Fault condition by
looking for the Fault icon on the
LCD. Interrogate the fault by
escaping to the Measure Mode
using the Exit to MEASURE Key and
the FAULT Info Key in that order.
c) See Section 14, Troubleshooting.