Teledyne 3000TA-XLEU - Trace oxygen analyzer - Manual (Page 23)

Trace Oxygen Analyzer Operational Theory
Teledyne Analytical Instruments 7
Operational Theory
2.1 Introduction
The analyzer is composed of three subsystems:
1. Micro-fuel Cell Sensor
2. Sample System
3. 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 Micro-Fuel Cell is an electrochemical
galvanic 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 Micro-Fuel Sensor
2.2.1 Principles of Operation
The oxygen sensor used in the Model 3000TA-XL series is a
Micro-Fuel Cell, Model B-2CXL designed and manufactured by
Analytical Instruments. It is a sealed plastic disposable electrochemical
transducer.
The active components of the Micro-Fuel Cell are a cathode, an
anode, and the aqueous KOH electrolyte in which they are immersed.
The cell converts the energy from a chemical reaction into an electrical
current in an external electrical circuit. Its action is similar to that of a
battery.
There is, however, an important difference in the operation of a
battery as compared to the Micro-Fuel Cell: In the battery, all reactants
are stored within the cell, whereas in the Micro-Fuel Cell, one of the
reactants (oxygen) comes from outside the device as a constituent of the
sample gas being analyzed. The Micro-Fuel Cell is therefore a hybrid