Product Description; Description Of The System - Swann AMU pH-Redox Operator's Manual

AMU pH-Redox

Product Description

2.
2.1.
Application
pH Measuring
Principle
(simplified)
ORP Measur-
ing Principle
(simplified)
Temperature
compensation
8
Product Description

Description of the System

pH and ORP are measured in many applications as for example
potable water, high purity water or waste water. Each application
requires different fittings, flow cells, and sensors.
The pH measurement is based on a voltage measurement. A volt-
age can only be measured between two different potentials, there-
fore, the pH measuring chain contains a measuring electrode and a
reference electrode. The reference electrode maintains a constant
potential whereas the potential of the measuring electrode changes
with the pH value. The voltage which results from this potential dif-
ference is measured and displayed on the transmitter as pH value.
The measuring chain is designed so that the voltage is zero at
pH 7.
The ORP (redox) measurement is based on a voltage measure-
ment. A voltage can only be measured between two different po-
tentials, therefore, the ORP (redox) measuring chain contains a
measuring electrode and a reference electrode. The reference
electrode maintains a constant potential whereas the potential of
the measuring electrode changes with the ORP value. The voltage
which results from this potential difference is measured and dis-
played on the transmitter as ORP value in millivolt (mV). Both elec-
trodes are integrated in one housing = combined electrode.
 pH: The pH value depends on the sample temperature. To
compensate temperature fluctuations a temperature sensor is
installed in the flow cell.
 ORP: Temperature compensation is not necessary.
Potable water, waste water: Compensation according to Nernst.
High purity water (Power plant, semiconductor): Nernst or non-lin-
ear solution temperature compensation, or linear compensation
with coefficient.
A-96.250.441 / 060619