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Lift station level measurement and control - v.17

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An exploration of six major ways lift station level measurement can be performed, along with their relationships to different methods of starters and controls

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Lift station level measurement and control - v.17

  1. 1. Lift Station Level Measurement & Control Brian Gongol DJ Gongol & Associates, Inc. October 25, 2017 Iowa WEA Region V Meeting Newton, Iowa
  2. 2. Controls: Level Measurement
  3. 3. FLOAT SWITCHES
  4. 4. Simplest
  5. 5. Imprecise
  6. 6. Lines can get pinched, nicked, or sliced
  7. 7. Cables frequently get tangled
  8. 8. Debris can catch on floats
  9. 9. Damaged floats can become hazards Floats that are dropped, cut, or damaged can become debris inside the wetwell that creates a clogging hazard for pumps and valves
  10. 10. Moving parts with wear every cycle
  11. 11. Retrieval
  12. 12. Replacement after retrieval Requires close attention to detail and/or careful measurement, but the task is frequently performed by junior members of staff because it is unpleasant. Those junior members may not have an adequate understanding of the nuances required for proper installation.
  13. 13. Explosion risk Must be furnished with appropriate circuitry if installed inside an explosion-proof location
  14. 14. Portable and easy to install
  15. 15. Suitable as a redundant backup
  16. 16. Water torture
  17. 17. Water torture Install floats so they are out of the flow path of any influent
  18. 18. ULTRASONIC TRANSDUCERS
  19. 19. Accuracy and reliability Loses accuracy when materials, grease, bubbles, or other interference floats on top of the pumpage
  20. 20. Temperature changes Sensitive to temperature changes, especially if the transducer is mounted on metal
  21. 21. Requires careful mounting
  22. 22. Loss of signal Can be persistent Can be difficult to resolve
  23. 23. Sensor heads can be subject to contamination
  24. 24. Warm sewage in cold weather Condensation can freeze on a cold sensor head
  25. 25. Recalibration Recalibration requires precise measurement of actual distances or elevations, which may require direct exposure to the hazards inside a wetwell
  26. 26. Circuitry requirements Must be furnished with appropriate circuitry for explosion-proof locations
  27. 27. Best used with a stilling well
  28. 28. SUBMERSIBLE TRANSDUCERS
  29. 29. High precision (often)
  30. 30. Sensitive parts exposed to pumpage
  31. 31. Subject to clogging
  32. 32. No positive cleaning of the transducer head
  33. 33. Retrieval For cleaning, recalibration, and testing
  34. 34. Recalibration process Requires a precise and fixed quantity of water
  35. 35. Who wants to recalibrate in cold weather?
  36. 36. Replacement after failure Have to duplicate with the same span and same outputs
  37. 37. Not cheap, not field-repairable
  38. 38. Again, explosion-proof requirements apply
  39. 39. AIR BUBBLERS
  40. 40. Simple and robust
  41. 41. Small air pump at the control panel
  42. 42. Produces a known air pressure
  43. 43. Air discharges through a flexible hose
  44. 44. Bubbling into an airbell in the wetwell
  45. 45. Backpressure indicates the water elevation
  46. 46. Air bubblers are attractive for several reasons
  47. 47. Measured to tenths of a foot
  48. 48. High degree of operator control
  49. 49. Simple and robust
  50. 50. No moving/corroding parts inside the wetwell
  51. 51. Safe for explosion-proof environments
  52. 52. No routine operator exposure to wetwell
  53. 53. Line pressure means constant positive cleaning
  54. 54. Air pumps the only mechanical components
  55. 55. Easy to repair and replace from above-ground
  56. 56. Air lines easy to clean from above if clogged
  57. 57. Air bell protects from grease and debris
  58. 58. Air line discharges below the water line
  59. 59. DIAPHRAGM SWITCH
  60. 60. Lower precision
  61. 61. Requires manual elevation adjustments
  62. 62. Subject to contamination
  63. 63. Switches can't be far apart
  64. 64. Subject to explosion-proof requirements
  65. 65. RADAR
  66. 66. New technology for level measurement
  67. 67. ** Controls: Starter Types **
  68. 68. On/off (across-the-line)
  69. 69. Soft start
  70. 70. VFD
  71. 71. Multiple-speed motor
  72. 72. ** Specialty control systems **
  73. 73. Parallel level controls
  74. 74. Independent redundant level controls
  75. 75. Redundant high-water alarms
  76. 76. Redundant low-water alarms
  77. 77. Questions?  Thank you for attending!  Brian Gongol DJ Gongol & Associates www.gongol.net info@gongol.net 515-223-4144  Twitter: @djgongol Facebook.com/djgongol
  78. 78. Credits  Photo of AMT submersible pump is courtesy of AMT Pump  Installation drawings of air-bubbler airbell and diaphragm switch both courtesy of the Gorman-Rupp Co.  Excerpt taken from USGS publication "Use Of Submersible Pressure Transducers In Water-Resources Investigations" is of a public-domain work  All other images are original work of the author. All rights reserved. No duplication or use is permitted without prior written consent.

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