Teledyne 3020T Operational Theory Introduction, Micro-Fuel Cell Sensor, Principles of Operation

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Trace Oxygen Analyzer

Operational Theory 2

 

 

 

 

 

 

 

 

 

Operational Theory

2.1Introduction

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.

2.2Micro-Fuel Cell Sensor

2.2.1 Principles of Operation

The oxygen sensor used in the Model 3020T series is a Micro-Fuel Cell 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 15% 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

Teledyne Analytical Instruments

2-1

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Contents Teledyne Analytical Instruments Model 3020TCopyright 1999 Teledyne Analytical Instruments Model 3020T3020T-I Trace Oxygen AnalyzerIii Specific Model InformationTable of Contents Introduction InstallationOperational Theory Operation MaintenanceAppendix Typical Applications Main Features of the AnalyzerTrace Oxygen Analyzer Introduction OverviewModel 3020T Model DesignationsTrace Oxygen Analyzer Introduction Operator Interface Model 3020T Controls, Indicators, and Connectors1 UP/DOWN Switch ESCAPE/ENTER SwitchPWD Displays Electrical Connector PanelRecognizing Difference Between LCD Equipment InterfaceRemote Valves RS-232 PortGas Connector Panel Remote SensorNetwork I/O Optional Operational Theory Introduction Micro-Fuel Cell SensorPrinciples of Operation Anatomy of a Micro-Fuel Cell Operational Theory+ 2H 2O + 4e → 4OH Electrochemical ReactionsEffect of Pressure Calibration CharacteristicsSample System Characteristic Input/Output Curve for a Micro-Fuel CellSpan Zero Sample Electronics and Signal ProcessingBlock Diagram of the Model 3020T Electronics Temperature Control Trace Oxygen Analyzer Installation Unpacking the AnalyzerMounting the Analyzer Front View of the Model 3020T Simplified Required Front Door Clearance Electrical ConnectionsPrimary Input Power Fuse InstallationAnalog Outputs Analog Output Connections ExamplesRange Voltage Current mA Alarm RelaysTypes of Relay Contacts Digital Remote Cal InputsZero RS-232 Sig RS-232 Pin Purpose Range ID RelaysNetwork I/O 8 RS-232 PortCommand Description Parameter SettingRemote Sensor and Solenoid Valves Remote Solenoid Return Connector Pinouts Installing the Micro-Fuel CellGas Connections Gas Connector Panel Testing the System Using the Controls Trace Oxygen Analyzer OperationAuto Ranging on Analysis Mode Setup ModeMode/Function Selection Trace Oxygen Analyzer Data Entry EnterEscape Trace Oxygen Analyzer Operation AUTO-CALFunction PWD Password FunctionEntering the Password Only one password can be definedInstalling or Changing the Password Version Screen Logout FunctionZero and Span Functions Trace Oxygen Analyzer Operation SELF-TESTFunctionZero Cal Auto Mode ZeroingManual Mode Zeroing Auto Mode Spanning Cell FailureSpan Cal Manual Mode Spanning Installation Alarms FunctionAL-1 AL-2 Choose Alarm Range Function Setting the Analog Output RangesFixed Range Analysis Standby Function Contrast FunctionAnalysis Mode Operation Trace Oxygen Analyzer Maintenance Routine MaintenanceMajor Internal Components Major Internal Components Cell ReplacementWhen to Replace a Cell Storing and Handling Replacement CellsRemoving the Micro-Fuel Cell Exploded View of Cell Block and Micro-Fuel Cell Installing a New Micro-Fuel Cell Fuse Replacement Cell WarrantyL-2C cell is not designed for applications where CO2 is a Removing Fuse Cap and Fuse from Holder System Self Diagnostic TestPower AnalogPreamp Maintenance Trace Oxygen Analyzer Appendix SpecificationsOperating Temperature 0-50 C Qty Part Number Description Recommended 2-Year Spare Parts ListDrawing List Series Analyzers Restrictor KIT Conversions