Table of Contents
Advertisement
15.1
Important information
15.2
General information
15.2.1
Calibration methods for CR conductivity sensors (conductive)
Rel. cell constant
Temperature coefficient
15 Calibrating CR conductivity sensors
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 calibration of CR sensors is based on measurements in test solutions with
a defined electrolytic conductivity. Since the electrolytic conductivity of liquids is
temperature dependent, the temperature of the test solution must be sensed.
This requires either manual entry or measurement with the aid of a temperature
sensor.
The deviation from the nominal cell constant of a CR sensor is described by the
relative cell constant. The rel. cell constant is determined by making a measure-
ment in a test solution with a defined conductivity.
The temperature coefficient is a measure of the temperature dependence of the
electrolytic conductivity of a liquid. It is used to compensate for the effect of tem-
perature when measuring the electrolytic conductivity. When performing a tem-
perature-compensated conductivity measurement, the conductivity value
measured is always indicated with reference to the fixed reference temperature.
With the aid of the temperature coefficient, the value of the electrolytic conduc-
tivity displayed at the reference temperature is calculated from the current mea-
sured values of conductivity and temperature of the liquid.
Reference temp. is set in the configuration of the individual CR analysis input.
⇨
Chapter 10.6.6 "CR/Ci analysis inputs (conductive/inductive conductivity)",
page 23
The temperature coefficient is determined from 2 measurements in a test solu-
tion at different temperatures (reference and operation temp.).
NOTE!
If the temperature coefficient of a sample solution is known, it can be entered
directly.
⇨
Chapter 11.2.1 "General procedure for calibration", page 49
71
Advertisement
Table of Contents
