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

1. Lift Station Level Measurement & Control
Brian Gongol
DJ Gongol & Associates, Inc.
October 25, 2017
Iowa WEA Region V Meeting
Newton, Iowa

2. Controls: Level Measurement

3. FLOAT SWITCHES

4. Simplest

5. Imprecise

6. Lines can get pinched, nicked, or sliced

7. Cables frequently get tangled

8. Debris can catch on floats

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. Moving parts with wear every cycle

11. Retrieval

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. Explosion risk
Must be furnished with appropriate circuitry if installed
inside an explosion-proof location

14. Portable and easy to install

15. Suitable as a redundant backup

16. Water torture

17. Water torture
Install floats so they are out of
the flow path of any influent

18. ULTRASONIC TRANSDUCERS

19. Accuracy and reliability
Loses accuracy when materials, grease, bubbles,
or other interference floats on top of the pumpage

20. Temperature changes
Sensitive to temperature changes,
especially if the transducer
is mounted on metal

21. Requires careful mounting

22. Loss of signal
Can be persistent
Can be difficult to resolve

23. Sensor heads can be subject to contamination

24. Warm sewage in cold weather
Condensation can freeze
on a cold sensor head

25. Recalibration
Recalibration requires precise measurement
of actual distances or elevations,
which may require direct exposure
to the hazards inside a wetwell

26. Circuitry requirements
Must be furnished with appropriate circuitry
for explosion-proof locations

27. Best used with a stilling well

28. SUBMERSIBLE TRANSDUCERS

29. High precision (often)

30. Sensitive parts exposed to pumpage

31. Subject to clogging

32. No positive cleaning of the transducer head

33. Retrieval
For cleaning,
recalibration,
and testing

34. Recalibration process
Requires a precise and fixed quantity of water

35. Who wants to recalibrate in cold weather?

36. Replacement after failure
Have to duplicate with the
same span and same outputs

37. Not cheap, not field-repairable

38. Again, explosion-proof requirements apply

39. AIR BUBBLERS

40. Simple and robust

41. Small air pump at the control panel

42. Produces a known air pressure

43. Air discharges through a flexible hose

44. Bubbling into an airbell in the wetwell

45. Backpressure indicates the water elevation

46. Air bubblers are attractive for several reasons

47. Measured to tenths of a foot

48. High degree of operator control

49. Simple and robust

50. No moving/corroding parts inside the wetwell

51. Safe for explosion-proof environments

52. No routine operator exposure to wetwell

53. Line pressure means constant positive cleaning

54. Air pumps the only mechanical components

55. Easy to repair and replace from above-ground

56. Air lines easy to clean from above if clogged

57. Air bell protects from grease and debris

58. Air line discharges below the water line

59. DIAPHRAGM SWITCH

60. Lower precision

61. Requires manual elevation adjustments

62. Subject to contamination

63. Switches can't be far apart

64. Subject to explosion-proof requirements

65. RADAR

66. New technology for level measurement

67. ** Controls: Starter Types **

68. On/off (across-the-line)

69. Soft start

70. VFD

71. Multiple-speed motor

72. ** Specialty control systems **

73. Parallel level controls

74. Independent redundant level controls

75. Redundant high-water alarms

76. Redundant low-water alarms

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. 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.