1. Applied to Proper Hardware Selection
Conductivity Theory
Applied to Proper Hardware Selection
Feb 2001
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
Feb 2001

3. Electrolytes Acids Bases Salts File Name: Conductivity.ppt Feb 2001
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
Feb 2001

4. Typical Conductivity Values
File Name: Conductivity.ppt
Feb 2001

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
Feb 2001

6. Conductivity Measurement
High Purity Water Applications
Power & Semiconductor Manufacturing
Conductivity Measured as Resistivity in MegOhms/cm
Pure Water = Meg Ohms/-cm = uS/cm
Water & Water Treatment Applications
Industrial Boilers & Cooling Towers
Conductivity Measured in Total Dissolved Solids (TDS)
File Name: Conductivity.ppt
Feb 2001

7. Conductance of Common Acids, Bases and Salts @ 25oC
File Name: Conductivity.ppt
Feb 2001

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 > %/oC
High Purity Water 2.3% - 7.3%/ oC
File Name: Conductivity.ppt
Feb 2001

9. Specific Conductivity of Sulfuric Acid
File Name: Conductivity.ppt
Feb 2001

10. 5.0% Sulfuric Acid Solution
File Name: Conductivity.ppt
Feb 2001

11. Change in Temperature Slope/oC
File Name: Conductivity.ppt
Feb 2001

12. 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
Na+
Cl-
File Name: Conductivity.ppt
Feb 2001

13. 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 V
File Name: Conductivity.ppt
Feb 2001

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
Feb 2001

15. Reverse Osmosis Unit File Name: Conductivity.ppt Feb 2001
pH Transmitter
Feed Water
Acid Feed
Feed
Water
Tank
Conductivity Transmitter
RO Unit
Waste
File Name: Conductivity.ppt
Feb 2001

16. Demineralizer Unit File Name: Conductivity.ppt Feb 2001
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
Feb 2001

17. Power Utilities Average Number of Analyzers for Each Demin Unit
Type Number
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
File Name: Conductivity.ppt
Feb 2001

18. Power Utilities Average Number of Analyzers Per Generating Unit
Analyzer Type Number
pH 5
Specific Conductivity 6
Cation Conductivity 11
Condensate Analyzer 1
Total 23
Usually Units Built in Pairs = 46 Analyzers
File Name: Conductivity.ppt
Feb 2001

19. Boiler Blowdown and Condensate Return Lines
Steam
Drum
Heat
Exchanger
Condensate Return
Top Blowdown Line
Conductivity
Transmitter
Blowdown Valve
Steam Header
Waste
Mud
Manual Blowdown Valve
Do Not Automate !
Feed
Water
Tank
Flash
File Name: Conductivity.ppt
Feb 2001

20. Clean in Place (CIP) File Name: Conductivity.ppt Feb 2001 Conductivity
Transmitter
CIP Return Lines
Caustic
Process
Vessels
Caustic
Dilution
Tank
Solution
Recovery
Conductivity
Transmitter
Water
File Name: Conductivity.ppt
Feb 2001