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Conductivity Theory

Conductivity Theory. Applied to Proper Hardware Selection. Conductivity Measurement. Used to Measure and Control the Percent Concentration of Acids, Bases and Salts in Solution Measures Total Concentration Not Ion Specific May be Used to Determine the Dominant Chemical. Electrolytes. Acids

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Conductivity Theory

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  1. Conductivity Theory Applied to Proper Hardware Selection File Name: Conductivity.ppt

  2. Conductivity Measurement • Used to Measure and Control the Percent Concentration of Acids, Bases and Salts in Solution • Measures Total Concentration • Not Ion Specific • May be Used to Determine the Dominant Chemical File Name: Conductivity.ppt

  3. Electrolytes • Acids • Substances which ionize in solution and produce hydrogen ions, H+ • Hydrochloric Acid (HCl) dissociates into H+ + Cl- • Bases • Substances which ionize in solution and produce hydroxide ions, OH- • Sodium Hydroxide, NaOH, dissociates into Na+ + OH- • Salts • Substances which ionize in solution and produce neither hydrogen or hydroxide ions • Sodium Chloride, NaCl, dissociates into Na+ + Cl- File Name: Conductivity.ppt

  4. Typical Conductivity Values File Name: Conductivity.ppt

  5. Conductivity Measurement • Units of Measurement • U.S. Units = Micromhos/cm • International Units = MicroSiemens/cm • 1.0 S/cm = 1,000 mS/cm = 1,000,000 uS/cm • umho/cm = uS/cm • Conductivity is the Reciprocal of Resistance • 1.0 MicroSiemen/cm = 1,000,000 Ohms/-cm • 1,000,000 MicroSiemens/cm = 1.0 Ohm/-cm File Name: Conductivity.ppt

  6. Conductivity Measurement • High Purity Water Applications • Power & Semiconductor Manufacturing • Conductivity Measured as Resistivity in MegOhms/cm • Pure Water = 18.18 Meg Ohms/-cm = 0.055 uS/cm • Water & Water Treatment Applications • Industrial Boilers & Cooling Towers • Conductivity Measured in Total Dissolved Solids (TDS) File Name: Conductivity.ppt

  7. Conductance of Common Acids, Bases and Salts @ 25oC File Name: Conductivity.ppt

  8. Conductivity Measurement • Each Acid, Base and Salt has Its Own Temperature Vs. Concentration Curve • The Temperature Slope Varies for Different Chemicals • Acids 1.0% - 1.6% /oC • Natural Waters 2.0%/oC • Bases > 1.8 - 2.2%/oC • High Purity Water 2.3% - 7.3%/ oC File Name: Conductivity.ppt

  9. Specific Conductivity of Sulfuric Acid File Name: Conductivity.ppt

  10. 5.0% Sulfuric Acid Solution File Name: Conductivity.ppt

  11. Change in Temperature Slope/oC File Name: Conductivity.ppt

  12. Na+ Cl- Conductivity Measurement • Apply an AC Voltage to Two Electrodes of Exact Dimensions • Acids, Bases and Salts (NaCl) Dissolve in Solution and Act as Current Carriers • The Current Flow is Directly Proportional to the Total Dissolved Solids in Solution • The Physical Dimensions of a Conductivity Electrode are Referred to as the Cell Constant • Cell Constant is Length/Area Relationship • Distance Between Plates = 1.0 cm • Area of Each Plate = 1.0 cm x 1.0 cm • Cell Constant = 1.0 cm-1 • Cell Constant • Used to Determine the Measuring Range of the Analyzer • Acts as Multiplier • Used to Calibrate Analyzer • Determined Using NBS Standards • Can be NIST Traceable File Name: Conductivity.ppt

  13. V Four Electrode Conductivity Cells • Measures Current and Voltage Drop • Current Increases with an Increase in Voltage Drop Across Electrodes • Compensates for Minor Coatings on Conductivity Electrodes • Used for Higher Range Measurement File Name: Conductivity.ppt

  14. Inductive Conductivity • Also Known as Toroidal and Electrodless • Principle of Measurement • Two Sealed Wire Wound Coils Electrically Coupled by Solution Conductivity • Advantage • No Electrodes Exposed to the Measured Solution • Not Affected by Coating • Disadvantage • +- 10% Accuracy • High Range Measurement Only > 100 uS/cm File Name: Conductivity.ppt

  15. Reverse Osmosis Unit pH Transmitter Feed Water Acid Feed Feed Water Tank Conductivity Transmitter RO Unit Waste File Name: Conductivity.ppt

  16. Demineralizer Unit Caustic Regeneration Acid Regeneration Conductivity Transmitter Conductivity Transmitter Anion Bed Mixed Bed Cation Bed Conductivity Transmitter To Water Storage Conductivity Transmitter Conductivity Transmitter File Name: Conductivity.ppt

  17. TypeNumber Conductivity 4 Concentration 2 pH 1 Total 7 Usually 2 per generation unit (make up & polisher) and built in pairs Total X 4 = 28 Analyzers per Unit Two Units Built at a time = 56 Analyzers Power Utilities Average Number of Analyzers for Each Demin Unit File Name: Conductivity.ppt

  18. Analyzer TypeNumber pH 5 Specific Conductivity 6 Cation Conductivity 11 Condensate Analyzer 1 Total 23 Usually Units Built in Pairs = 46 Analyzers Power Utilities Average Number of Analyzers Per Generating Unit File Name: Conductivity.ppt

  19. Conductivity Transmitter Heat Exchanger Feed Water Tank Condensate Return Waste Steam Header Conductivity Transmitter Steam Drum Top Blowdown Line Blowdown Valve Mud Drum Flash Tank Manual Blowdown Valve Do Not Automate ! Boiler Blowdown and Condensate Return Lines File Name: Conductivity.ppt

  20. Clean in Place (CIP) Conductivity Transmitter CIP Return Lines Caustic Process Vessels Caustic Dilution Tank Solution Recovery Conductivity Transmitter Water File Name: Conductivity.ppt

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