Teledyne 6750 operating instructions UV/Heated Persulfate Method of Analysis

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Total Organic Carbon Analyzer

Theory of Operation

 

 

 

2.3 The UV/Heated Persulfate Method of Analysis

In the UV/Heated Persulfate Method as used by the Model 6750, the sample is initially mixed with acid and directed to the sparger. For TOC-Direct (NPOC) analysis, the CO2 converted from the inorganic carbon is sparged out of solution by the carrier gas and vented to atmosphere. Any volatile organic loss would occur at this point, exiting the sparger as HC gas. For TOC-True, the TIC-related CO2 is measured by the NDIR CO2 detector, which is blind to the HC. For NPOC analysis, the liquid, carbonate-free sample is then directed to the UV reactor, where the remaining organic carbon is oxidized to CO2 and measured by the NDIR as a "TOC-Direct" (or NPOC) analysis.

NDIR analysis of CO2 is specific and interference-free and is used in all critical and regulatory applications. The TOC-Direct method is the most accurate TOC analytical method, as determined by the EPA and other governmental agencies. Teledyne also offers conductivity detection but it is of limited use in these applications and is not proposed as a primary detection method for TOC analysis, especially in critical industrial applications where multiple or unknown analytes are present. Figure 2-5 compares both CO2 detection methods.

For the TC analysis, the combined liquid/gas sample is sent directly to the reactor, where all carbon (including the volatile HC) is converted to CO2. The NDIR thus measures the TOTAL CO2 (including that

generated from the TIC, volatile HC and NPOC) and reports it as "TC."

The important thing is that all measurements are made on the same sample, eliminating potential sample introduction errors and multiple sampling inaccuracies.

Teledyne Analytical Instruments

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Contents Teledyne Analytical Instruments ModelCopyright 2005 Teledyne Instruments/ Analytical Instruments ModelTotal Organic Carbon Analyzer Specific Model InformationSafety Messages Total Organic Carbon Analyzer Table of Contents Maintenance Setup and OperationIndex Teledyne Analytical Instruments AppendixModel 6750 TOC Analyzer Front door removed List of FiguresDC Power Supply Module List of Tables Combustible GAS Usage Main Features of the Analyzer IntroductionTotal Organic Carbon Analyzer Introduction Typical Applications OptionsIntended Use of the Analyzer Introduction ModelModel 6750 TOC Analyzer Front door removed Operator InterfaceIntroduction Model Teledyne Analytical Instruments Overview Theory of OperationBackground Total Organic Carbon Analyzer Theory of OperationNpoc or TOC Direct Method Theory of Operation ModelConclusion TOC Measurement Basics UV/Heated Persulfate Method of Analysis Comparison of TOC Measurement Technologies Sample Handling Subsystems Principles of OperationSample Handling for TOC -Direct Sample Handling TOC-True Inorganic Carbon Removal/Analysis TOC analysis in a continuous, on-line TOC analyzerOxidation Relationship Between TIC and pHOxidation Reactions 10 Model 6750 Ndir Unit Ndir CO2 Gas DetectionElectronic Signal Processing, Display and Control BENCHMARK/AUTO-VALIDATION Theory of Operation Model Teledyne Analytical Instruments Total Organic Carbon Analyzer Installation InstallationUnpacking the Analyzer Mounting the AnalyzerAnalyzer Dimensions Installation ModelElectrical Connections Power ConnectionElectrical Connections to the Model Analog OutputsGas/liquid Connections Alarm Connections4 RS-232 Serial Connection Liquid ConnectionsGas Connections Gas and Liquid Connections to the AnalyzerGas Carrier Connections Checking the SystemInstallation Model Teledyne Analytical Instruments Setup and Operation Total Organic Carbon Analyzer Setup and OperationAnalyzer Startup Drain Connections Setup and Operation ModelMenus Run ModeParameter Menu Alarm Settings Stream Sequencer 5 D/DBPR Detailed Calibration Procedures Ethylene Glycol 100 mg/Liter 1000 mg/LiterMethanol EthanolPreparation of Phosphoric Acid Solution Total Organic Carbon Analyzer Setup and Operation RUN Screen OperationHistorical Data ShutdownSetup and Operation Model Maintenance Compupter-aided TestingTotal Organic Carbon Analyzer Maintenance Maintenance Model TroubleshootingNdir Gas Calibration Module ServiceIR Calibration Ndir Service Installing Calibration AdapterRemoving the Ndir Unit P/N ST36000 Total Organic Carbon Analyzer Maintenance Maintenance Model To Reassemble Use alternate tightening sequence Removing the Master Interface Board Master Interface Board P/N ST13042-1DC Power Supply Module 4 D. C. Power SupplyReplacing CE Computer CE Computer P/NUV Lamp P/N ST20009 UV Lamp ReplacementRemoving the UV Reactor Assembly UV Reactor Assembly P/N ST20003-1UV Power Supply Mass Flow Controller P/N ST18001A 10 Removing the UV Power SupplyMetering Valve P/N ST16050 11 Mass Flow ControllerSparger P/N ST20025 12 Metering Valve13 Sparger Pumps Maintenance Model 14 Removing the Pump Maintenance Model System Diagnostics 13 4-20 mA Adjustment ProcedureSetting 100 MV Control Voltage 1Specifications AppendixTotal Organic Carbon Analyzer Appendix Sample requirements Appendix ModelDescription Image Parts ListingAppendix Model Total Organic Carbon Analyzer Appendix Appendix Model Total Organic Carbon Analyzer Appendix Auto CAL OptionDbpr Option True Dual Range Option not an electronic scalingAppendix Model AS-BUILT Drawings Appendix Model Teledyne Analytical Instruments Total Organic Carbon Analyzer Index IndexModbus Index ModelPump mounting screw Index Model