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11.1
Important information
11.2
General information
11.2.1
General procedure for calibration
True calibration (calibrating with routines)
WARNING!
During the calibration, the relays and analog output signals assume the states
configured for the calibration! The response of the output signals is set for each
output in its "Response at calibration" configuration point.
⇨
Chapter 10.7 "Analog outputs of base unit and optional boards", page 28
The actual electrical characteristics of analysis sensors always deviate some-
what from the nominal specifications. The reasons for this include:
•
Like every measuring instrument, analysis sensors always have a certain
uncertainty of measurement that results from manufacturing tolerances.
•
During use, analysis sensors are exposed to chemical processes. Deposits
and wear phenomena caused by these processes result in changes of the
electrical characteristics of sensors.
To optimize the accuracy of measurements, analysis sensors must be calibrat-
ed. Calibrations are required:
•
during installation or when changing a sensor
•
regularly at time intervals that must be specified by the user
•
if implausible measured values are displayed
•
if process conditions change, e. g. as the result of equipment modification
Calibration timers can be configured to provide a regular reminder of when cal-
ibrations are due.
⇨
Chapter 10.12 "Calibration timer", page 46
Each successfully completed calibration is recorded in the calibration
logbook.
⇨
Chapter 11.3 "Calibration logbook", page 51
After opening one of the calibration routines in the device, the user is guided
through a process with measurements and entries. In the course of this process,
the calibration values are determined and saved automatically.
Suitable calibration routines are available for every type of analysis sensor. The
individual calibration routines for the various sensor types are described in sep-
arate chapters.
⇨
Chapter 12 "Calibrating a pH measuring chain", page 55 to Chapter 16 "Cali-
brating Ci conductivity sensors", page 79
Execution of calibration routines requires that the following prerequisites be met:
11 Calibration in general
49
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