Designing a Bulk Sodium Hypochlorite System

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Designing a Bulk Sodium Hypochlorite System

• Presented by Patrick H. Allman III
• General Manager
• Odyssey Manufacturing Co.

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Disinfection Options June 1999
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Disinfection Options June 2003
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Disinfection Options June 2005
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Sodium Hypochlorite

• Bleach
• Liquid Bleach
• Liquid Chlorine
• Soda Bleach Liquor
• Chlorine

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CHEMICAL FORMULA

• NaOCl

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Manufacturing Process

• 2NaOH Cl2 NaOCl H20 Heat

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Properties of Sodium Hypochlorite

• Mildly Corrosive
• Has Free Sodium Hydroxide (Caustic Soda)
• pH12.5 to 13
• Pale Yellow Solution, 12.5 By Volume
• Non-Flammable
• Incompatible with Many Other Chemicals
• Relatively Short Shelf Life - Contaminants, Heat
  And UV Cause Decomposition

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Contrary to Whites Handbook of Chlorination

• One Gallon of 120 GPL or 12 Trade Percent
• Equals
• 1 lb of Cl gas

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BLEACH DEGRADATION

• Primary
• 3NaOCl 2NaCl NaClO3 (Sodium Chlorate)
• Secondary
• 2NaOCl 2NaCl O2 (Gassing)
• Factors
• Heat
• UV (e.g., Sunlight)
• Impurities (Primarily Heavy Metals)
• Strength (Rate K (OCl-2

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Sodium Hypochlorite Degradation Average
Manufacturer _at_ 70 Degrees F

• Time of Manufacture - 12.5 Trade Percent
• 2 Days Later 12.43 Trade Percent
• 7 Days Later 12.25 Trade Percent
• 14 Days Later 12.01 Trade Percent
• 21 Days Later 11.78 Trade Percent
• 28 Days Later 11.55 Trade Percent
• 35 Days Later 11.34 Trade Percent

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Sodium Hypochlorite Degradation Average
Manufacturer _at_ 80 Degrees F

• Time of Manufacture - 12.5 Trade Percent
• 2 Days Later 12.34 Trade Percent
• 7 Days Later 11.96 Trade Percent
• 14 Days Later 11.47 Trade Percent
• 21 Days Later 11.01 Trade Percent
• 28 Days Later 10.59 Trade Percent
• 35 Days Later 10.21 Trade Percent

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Use of Pilot or Temporary Systems

• To Maintain Continuous Disinfection During
  Conversion Construction
• To size pumps and bulk storage tanks
• To Determine Finished Water Quality
• To Test different types of Equipment
• Familiarize Operations Personnel with Sodium
  Hypochlorite
• Verify Operations in Unusual Situations

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Sodium Hypochlorite System Design

• Delivery
• Bulk Storage
• Chemical Feed Equipment
• Piping

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Delivery to End-User

• Bulk Delivery in 5,000-gallon tanker truck
• Poured from Small Delivery 26 Flat-Bed Truck
  w/installed HDLPE totes or tanks
• 300-gallon totes (forklift)
• 55 gallon drums
• 15, 30 gallon totes
• 2.5 gallon jugs

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Bulk Delivery by Tanker Truck
FRP Tanker Trailer
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Bulk Delivery Site Should Have . . .

• 2 Supported Male Connection w/Cap
• Bag Filter 1 micron
• Safety Shower/Eye Wash/Running Water
• Security/Lights
• Hook Up Protection / Labeled Lines
• Proper Venting for Blow Off
• Catch Bucket
• Accessible Roadway and Turn Around

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Fill Line

• Air Pressure 15 to 25 psi
• Trucks Carry Up to 60 Hose
• Long Length Consider Upsizing to 3
• Length Proportional to Offload Time
• Maximum Length 200
• Proper supports 45 Degree Down
• Keep Line Vented

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Bulk Storage Tanks

• Location Covered vs. Non-Covered / Other
  Chemicals On-site
• Air Conditioning Storage Spaces
• Dilution of Stored Material Use Soft Water
• Type (FRP vs. Bulk)
• Size or Volume and Number (10 to 40 days)
• Use of Day Tanks (F.S. 62-555)
• Measuring Daily Usage (F.S. 62-555)
• Tie Downs

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Storage Tank Fittings

• Vents (2 or 3) Use Vinyl Bug Screen
• Drains Minimize of Tank Penetrations
• Fill Line Fill from Top not Side or Bottom
• Overflow Line Maximize Use of Tank
• Sight glasses Type/Operational Necessity
• Tanks Squat - Flexible Connection at Bottom
• Feed Line - Pulling Out of the Top or Bottom
• Bottom Fittings Types/Titanium is only
  acceptable Metal
• Gaskets Viton Only No EPDM

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Containment

• Requirements Florida Statues/RQ
• HDLPE Tubs
• Poured Wall / Concrete Block Wall
• Coatings
• Wall Penetrations

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Types of Piping

• Schedule 80 PVC Most Commonly Used
• Schedule 80 CPVC Plasticization
• Schedule 40 Should Not Be Used
• Kynar Expensive/Workmanship Issues
• Carbon Steel Lined with Teflon or Kynar
  Typically used in Power Plants Beware of Sizing
  Issues

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PVC Applications Socket Welding vs. Threaded
Connections

• Minimize the Use of Threaded Connections
• Use Stainless Steel Re-inforced Fittings on
  Threaded Joints When Possible Pump Discharge
  Fittings
• If you must use a threaded connection, two wraps
  of Teflon Tape only
• Use proper glue procedure 45-Degree Bevel,
  Debur, Clean/Prime, and Glue Each End.
• Use proper Glue
• IPS WELDON CPVC 724 24 to 48 hrs setup time
  (grey)
• IPS EZ WELDON WET R DRY PVC 725 10 minutes
  under low pressure (blue)

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Valves

• Use the same model of Valve throughout the entire
  project Standardize!
• True Union with Viton o-rings No EPDM
• Bleed Hole for Pressure Buildup
• Socket Weld Ends, No Threaded Connections

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Piping to Chemical Feed Equipment

• Purpose Minimize Off-Gassing
• Pipe Sizing Optimize velocity
• Minimize Length Maximum 50
• Stack Vents/Sightglasses Carry Off Gases
• Minimize Bends Keep Gases in Solution
• Use of Flexible Piping/Tubing
• Eliminate High Spots Piping Pitch
• Use of Strainers Catch PVC shavings

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Chemical Feed Equipment

• Eductors vs. Positive Displacement Pumps
• PD Pumps Peristaltic vs. Diaphragm
• Pump Skids vs. Wall /Floor Mounting
• Height of Equipment Suction Lift Issues
• Degasification Valves When To Use
• Vapor Lock Issues Bleed Valve or Vent
• Control Issues Flow Meters / 4-20 ma
• 99 of Most Operational Problems Come from
  Over-sizing Pumps!

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Chemical Injection Piping

• Proper Sizing of Pipe Minimize Off-gassing and
  Provide Precision Control of Feed Rate
• Backpressure Valves at End of Pipe Improve Feed
  Rate Control
• Maximum Length of Injection Point 500
• Turnover Time Less than 4 hours
• Use of Solution or Carry Water
• Design of Injection Points
• Mixing Issues
• Minimizing Calcification/Scaling

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Water Quality Issues

• pH Boost - Typically .3 to .4 Units (.1 with
  OSG)
• THMs Typically slight reduction (from Chlorine
  Gas)
• Bromates Can Be Problematic with Ozone and Some
  Salt Sources (OSG) Ensure Quality Supplier
• Chlorates May Be Regulated in the Future
  Ensure Quality Supplier
• Chlorides/Sodium Ensure Quality Supplier
• Alga Control Bulk Strength as effective as
  Chlorine Gas
• Chloramine Formation May be slightly more
  effective than Chlorine Gas because of pH shift

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SYSTEM DESIGN SUMMARY

• Proper Engineering Design Essential To
• Eliminate Problems from Any Bleach Gassing
• Eliminate Calcium Carbonate Buildup
• Minimize Product Degradation
• Improve Life of Equipment
• Minimize Maintenance
• Ensure No Startup Problems
• Eliminate Problems from Using a Corrosive
  Material

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Information Sources for Bleach

• Chlorine Institute Pamphlet 96
• AWWA Standard B300-99
• ANSI/NSF Standard 60
• AWWA Reference Library
• Material Safety Data Sheet (MSDS)
• Sodium Hypochlorite Manufacturer
• Equipment Fabricators (e.g. Pump Skids)