Teledyne 3160 manual Operational Theory Micro-Fuel Cell Sensor, Sample System

Page 13

Operational Theory 2

2.1.1 Micro-Fuel Cell Sensor

The Micro-Fuel Cell is a sealed plastic disposable oxygen transducer that mea- sures 1¼ inches in diameter and is ¾ inch thick. Inside of the cell are a cathode and anode immersed in 15% aqueous KOH electrolyte. At one end of the sensor is a Teflon diffusion membrane; the other end is sealed with a polyethylene membrane. At the rear of the cell is a contact plate consisting of two concentric foils. The foils mate with spring-loaded contacts in the sensor block assembly and provide the electrical connection to the rest of the analyzer.

The sensing cathode, located beneath the diffusion membrane, has a surface area of 2.48 cm2. The sample gas enters the sensor block through an inlet tube between the cathode and the sensor block cap, diffuses through the Teflon membrane, and any oxygen in the sample gas is reduced on the surface of the cathode by the following mechanism:

O

2

+ 2H O + 4e– → 4OH–

(cathode)

 

2

 

When the oxygen is reduced at the cathode, lead is simultaneously oxidized at the anode by the following mechanism.

2Pb → 2Pb+2 + 4e–

(anode)

The electrons released at the surface of the anode flow to the cathode surface via an external circuit. This current is proportional to the amount of oxygen. It is mea- sured and used to determine the oxygen concentration in the gas mixture.

The overall reaction for the fuel cell is:

2Pb + O2 → 2PbO

The output of the fuel cell is limited by the amount of oxygen in the cell at any one time, and the amount of stored anode material. In the absence of oxygen, there is no current generated.

2.1.2 Sample System

The sample system delivers gases to the Micro-Fuel Cell sensor from the ana- lyzer rear panel inlet. Depending on the mode of operation either a sample or zero gas is delivered.

The Model 3160 sample system is designed and fabricated to ensure that the oxygen concentration of the gas is not altered as it travels through the sample system.

The following list of sample system and analyzer features are among those available, but the exact configuration depends on the standard options incorporated. Paragraph 1.3 contains a list of the standard variations on the basic model.

TELEDYNE ANALYTICAL INSTRUMENTS

2-3

Page 12 Page 14
Image 13
Page 12 Page 14
Contents Model Copyright 1999 Teledyne Analytical Instruments Iii Table of Contents Appendix Maintenance & TroubleshootingTeledyne Analytical Instruments Fixed Features FeaturesVariable Features IntroductionIntroduction Options and Model Numbers Introduction Components3160DA Dual fuel cell Introduction Applications Principles of Operation Operational TheoryMajor Components Sample System Operational Theory Micro-Fuel Cell SensorOperational Theory Model 3160 flow schematic Electronics and Signal ProcessingOperational Theory Identifier Range Scale Voltage CurrentmA Analog signal output offsetDefaults Programmable Options Unpacking the Analyzer InstallationFront Panel Qty DescriptionRear Panel Analyzer front and rear panels Span Gas Installation Gas Line ConnectionsInstrument Air Compressed Air Fitting Sample GasSensor Installation Electrical Connections 3160 Rear Panel Voltage SelectionRemoving the Voltage Card Fuse ChangingFuse Replacement 3 RS-232 Serial Digital Port Installation ChecklistFront Panel Controls OperationsSpinning Wheel Modes of OperationCell Output Factor Span Factor Operations Uled Span in Progress Changing Passwords For Remote Monitoring and ControlOperations Cold Start-Up Operations Calibration Zeroing Operations Operations Calibration Using Span Gas Operations Operations Operations Select Active Sensor Two Cells Only Setup Operations Accpt Operations O2 Range Set-UpCold Start Operations Set-Up AlarmsOperations Operations Logger Set-Up Operations Operations Set-Up Clock Functions Accpt Teledyne Analytical Instruments Operations Operations System Statistics Ascii Data Bits 7 or Stop Bits 1 or Baud rateComm. Std. for 1200B Bell USA/CCITT Operations Operations Routine Maintenance Maintenance & TroubleshootingSensor Maintenance Scrubber MaintenanceSymptom Cause Correction TroubleshootingMaintenance & Troubleshooting Symptom Cause Correction Maintenance & Troubleshooting Operating Temperature0-50C 32 -122 F SpecificationsAppendix Teledyne Analytical Instruments Altitude 1,609 m Relative Humidy Up to 99%Drawing List Appendix Recommended Spare Parts ListCustomer Service Extension Environmental Health Appendix Material Safety Data SheetDate Prepared 2/12/96 Material or Component S. # QuantitySection IV Fire and Explosion Hazard Data Exposure Protective measures during cell replacementSection Viii Control Measures Manufacturer Product NameAddress PhonePrimary route of entry Signs/symptoms of exposureExposure limits Osha PEL Effects of overexposure IngestionDisposal Protective measures
Top Page Image Contents