RADIOMETER ABL90 FLEX User Manual

5. Sensors and optical system ABL90 FLEX reference manual
5-24
Measuring principle of the pCO
2
sensor
The electrode chain (or electrical circuit) set up to measure pCO
2
is illustrated in
the following diagram:
The electrode chain describes an electrical circuit consisting of the following:
Item Part Description
1 Voltmeter Measures the voltage potential in the
circuit.
2 pH electrode Provides electrical connection to the
voltmeter
3 Electrolyte solution Medium for connection
4 Internal reference electrode
(Ag/AgCl)
Provides electrical connection to the
voltmeter
The potential differences at all the junctions in the electrode chain are known
and constant, except that at the pH-sensitive membrane. (See the section
pH
and electrolyte sensors
for a full explanation.)
The potential difference at the pH-sensitive membrane depends on the pH of the
electrolyte solution, which in turn depends on the CO
2
content of the sample.
This is explained in the measuring process below.
Electrode chain
Parts and
description
Electrode chain
potential

RADIOMETER ABL90 FLEX Specifications

General

Brand	RADIOMETER
Model	ABL90 FLEX
Category	Measuring Instruments
Language	English