Teledyne 3190 - OEM trace oxygen analyzer - Manual (Page 13)

2-1
Trace Oxygen Analyzer Operational Theory 2
Teledyne Analytical Instruments
Operational Theory
2.1 Introduction
The analyzer is composed of two subsystems:
1. Analysis Unit with Micro-Fuel Cell Sensor
2. Control Unit with Signal Processing, Display and Controls
The Analysis Unit is designed to accept the sample gas and direct it to
the sensitive surface of the Micro-Fuel Cell sensor. The Micro-Fuel Cell is
an electrochemical galvanic device that translates the amount of oxygen
present in the sample into an electrical current.
The Control Unit processes the sensor output and translates it into
electrical concentration, range, and alarm outputs, and a trace oxygen
meter readout. It contains a microcontroller that manages all signal pro-
cessing, input/output, and display functions for the analyzer.
2.2 Micro-Fuel Cell Sensor
2.2.1 Principles of Operation
The oxygen sensor used in the Model 3190 is a Micro-Fuel Cell
designed and manufactured by TAI. It is a sealed, disposable electrochemi-
cal transducer.
The active components of the Micro-Fuel Cell are a cathode, an
anode, and the 15 % aqueous KOH electrolyte in which they are immersed.
The cell converts the energy from a chemical reaction into an electrical
current through 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