Teledyne BDS-3000 - Oxygen analyzer - Manual (Page 21)

Oxygen Analyzer Operational Theory
Teledyne Analytical Instruments 7
Operational Theory
2.1 Introduction
The analyzer is composed of three subsystems:
• BDS Sensor
• Sample System
• Electronic Signal Processing, Display and Control
The sample system is designed to accept the sample gas and
transport it through the analyzer without contaminating or altering the
sample prior to analysis. The BDS Sensor is an electrochemical device
that translates the amount of oxygen present in the sample into an
electrical current. The electronic signal processing, display and control
subsystem simplifies operation of the analyzer and accurately processes
the sampled data. The microprocessor controls all signal processing,
input/output and display functions for the analyzer.
2.2 BDS Sensor
2.2.1 Principles of Operation
The BDS oxygen sensor technology developed at Teledyne
Analytical Instruments is a result of TAI’s heavy investment on R&D
and expertise established during the half-century’s manufacturing of
electrochemical oxygen sensor. It stands for Bipotentiostat Driven
Sensor. A BDS oxygen sensor accurately translates the oxygen level in
the sample gas into to an electrical current signal.
A potentiostat contains three electrodes: a working electrode, a
reference electrode and a counter electrode. A Bipotentiostat is a
combination of two potentiostats that share the reference electrode and
the counter electrode. The potential at the working electrode is precisely
controlled with respect to the
reference electrode. The counter electrode
is used to carry the current that flow through the sensor. A potentiostat is
typically constructed with several operational amplifiers. The three
electrodes in an electrochemical cell and the operational amplifiers in