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Top ten hassles in wastewater pumping -- and how to avoid them

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Maintenance is often a necessary evil -- most people don't like doing it, but the less it's done, the worse the consequences. Here are some observations about ten of the most common hassles encountered in wastewater pumping applications and how to avoid (or at least reduce) them.

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Top ten hassles in wastewater pumping -- and how to avoid them

  1. 1. TOP 10 HASSLES IN WASTEWATER PUMPING Brian Gongol DJ Gongol & Associates, Inc. October 7, 2016 Iowa WEA Region IV Meeting Atlantic, Iowa
  2. 2. Ten common problems in no particular order Your troubles will vary
  3. 3. Problem #1: Clogging
  4. 4. There's no such thing as "non-clog" Shall we go looking for unicorns, too?
  5. 5. Is this real life? Or is this just fantasy? Anyone who insists that a pump is "non-clog" clearly hasn't seen the kinds of things real people dump down the drain
  6. 6. ANY pump can clog. Period.
  7. 7. What matters  Resistance to clogging  How quickly the pump can be unclogged  How quickly the pump can return to service
  8. 8. Trash baskets  People don't use them because they clog  ...but then the pumps clog
  9. 9. VFDs are not a magic pill They can be helpful in some cases, but they risk running too slowly
  10. 10. Low pump speeds can reduce inlet velocities And slow inlet velocities can lead to clogging
  11. 11. Use caution with shredders and grinders
  12. 12. Solids passage beats solids decimation It is often better to pass a large solid intact than in many small bits
  13. 13. Pass the whole baseball...
  14. 14. ...or all of the string and bits inside it?
  15. 15. Small solids plus high FOG A recipe for disgusting trouble
  16. 16. Solids with neutral buoyancy May be invisible from surface inspection but still cause clogs
  17. 17. You can't prevent every clog (Not as long as idiots can still flush mop heads)
  18. 18. Half-filled basketballs
  19. 19. Waterlogged wood
  20. 20. Drywall, insulation, and sheets of liner material
  21. 21. Storms will always bombard wetwells
  22. 22. Backflushing/jetting doesn't always solve it If the debris is still there, the problem is too
  23. 23. Clogged piping may require cutters
  24. 24. Wetwells may require vacuum trucks
  25. 25. New pumps may clog when old ones didn't For instance: Better suction pulls settled material from the wetwell
  26. 26. Prevent clogs  Make sure you have true 3" clearances  Keep the wetwell clear  Run pumps at appropriate speeds
  27. 27. But when clogs happen...
  28. 28. Ask: How quickly can you return to service?
  29. 29. How much does downtime really cost?
  30. 30. Total cost of a clog  Cost of pump downtime  Cost of extraction  Cost of labor (service charges or your own time)  Cost of transit  Cost of unclogging  Cost of parts  Cost of bypass pumping if required  Cost of sewer backup risk  Cost of reinstallation
  31. 31. And one very important cost The opportunity cost of your time
  32. 32. Opportunity cost  You might be a pump specialist  You might be a jack of all trades  Either way...
  33. 33. You have to place a value on your time
  34. 34. Opportunity cost The cost of doing one thing when you could be doing something else
  35. 35. Real total costs Real total cost = out-of-pocket cost + labor cost + opportunity cost
  36. 36. Don't overlook other potential clogging sites  Lines to air release valves  Drain lines  Cooling jackets  Gauge taps
  37. 37. Little clogs, big headaches  Rubber center of a golf ball  Springs
  38. 38. Problem #2: Cavitation
  39. 39. Cavitation can occur on suction or discharge
  40. 40. Any centrifugal pump is at risk  Submersible  Flooded-suction  Suction-lift
  41. 41. Cavitation cause #1 Errors in system design
  42. 42. Cavitation cause #2 Pump clearances open up over time due to wear
  43. 43. Cavitation cause #3: Valve changes Even when seemingly innocuous
  44. 44. Cavitation cause #4 Broken, damaged or closed ARVs on a forcemain
  45. 45. Cavitation cause #5 Force main constriction due to sedimentation, air pockets, or other changes in condition
  46. 46. Cavitation cause #6: Broken mains and valves
  47. 47. Listen closely: Suction cavitation
  48. 48. Listen closely: Discharge cavitation
  49. 49. Document performance with all of your senses Documentation is the only way to report the full story
  50. 50. Or maybe all but one.
  51. 51. We too often use sight as a crutch Sounds, smells, vibrations, and temperatures all matter
  52. 52. If you're at risk for cavitation  Hardened parts can reduce wear  Hardening delays the pump from falling out of tolerance
  53. 53. Ask this How easily can the tolerances and clearances be maintained?
  54. 54. Identifying cavitation by autopsy Discharge-side cavitation
  55. 55. Identifying cavitation by autopsy Suction-side cavitation
  56. 56. Uniform abrasive wear isn't cavitation
  57. 57. Problem #3: Animals, vermin, and nature being a jerk
  58. 58. Warm, protected spaces are attractive
  59. 59. Seal your gaps with gaskets
  60. 60. Keep doors closed
  61. 61. Patch holes
  62. 62. Keep things off the floor
  63. 63. Containerize with plastic
  64. 64. Containerize with plastic Avoid wood, cardboard, and metal
  65. 65. Sweep and clean up
  66. 66. A place for everything; everything in its place
  67. 67. Natural enemy: Muskrats  Swim into warm wetwells  Get sucked up into pipes and pumps (they're squishy)
  68. 68. Natural enemy: Turtles  Swim into warm wetwells
  69. 69. Natural enemy: Turtles  Block off suction inlets
  70. 70. Natural enemy: Turtles  Cause pumps to overheat and shut down
  71. 71. Natural enemy: Turtles  Swim away once the lag pump lowers the wetwell to the off-elevation
  72. 72. Natural enemy: Turtles  The operator gets the call, runs out to the station and can't find anything wrong
  73. 73. Natural enemy: Rattlesnakes Especially in Southern and Eastern Iowa
  74. 74. Natural enemy: Bees, wasps, and hornets
  75. 75. Natural enemy: Spiders
  76. 76. Ask: Can we really keep the pump station clean? Showroom clean may be too ambitious, but do aim for functionally clean
  77. 77. Problem #4: Lubrication
  78. 78. Seals  Oil-lubricated  Grease-lubricated  Water-lubricated  Lubrication by media
  79. 79. Bearings Oil or grease
  80. 80. Maintenance charts
  81. 81. Treat it like a bowling scorecard
  82. 82. Clean up spills
  83. 83. Use simple checklists
  84. 84. Rule of 7
  85. 85. Rule of 7
  86. 86. Problem #5: Seal failures
  87. 87. Cause: Debris like sand and grit
  88. 88. Cause: Alignment problems
  89. 89. Cause: Mechanical vibration
  90. 90. Cause: Hydraulic imbalance
  91. 91. Ask: Can I replace my own seals?
  92. 92. Keep pump stations clean
  93. 93. You can only see what's wrong if you know what looks right
  94. 94. Problem #6: Motor failure
  95. 95. Power surges and lightning strikes
  96. 96. Excessive starts per hour
  97. 97. Mice building nests in motors
  98. 98. Car accidents can cause pump problems
  99. 99. Car accidents can cause pump problems  Power line comes down  Power company makes repairs  Phases get reversed  Pump runs backwards
  100. 100. VFDs at a distance VFDs more than 100' from the motor can cause reflected waves
  101. 101. Use infrared temperature sensors to track
  102. 102. Know the motor's lubrication requirements
  103. 103. Ask: Are replacement motors readily available?
  104. 104. Ask: Are the sensors useful? For submersibles: Do moisture sensors give you time to react? For ODP/TEFC: Is it worth doubling or tripling the cost of an off-the-shelf motor?
  105. 105. Problem #7: Temperature problems
  106. 106. Overheating...and freezing
  107. 107. Proper ventilation for summer and winter
  108. 108. Heaters are cheap
  109. 109. Frozen water-line epidemic of 2014 Don't waste a good, widely-experienced crisis! People forget pain very, very quickly
  110. 110. Ask: Are we using the right enclosures?
  111. 111. Problem #8: System changes
  112. 112. System head curves change over time
  113. 113. Wear can cause pump performance to change
  114. 114. Sedimentation adds to friction losses
  115. 115. Water hammer can break valves and pipes
  116. 116. Ask: Is the system protected against surges?
  117. 117. Air buildup where ARVs should be installed
  118. 118. ARVs can fail, raising discharge heads
  119. 119. Ask: Do we have ARVs and surge valves?
  120. 120. Document performance on a pump curve
  121. 121. Problem #9: Vortexing and air entrainment
  122. 122. All centrifugal pumps are susceptible
  123. 123. Pumps are meant to move water If you need to move air, get a fan
  124. 124. Air leads to irregular shaft loads
  125. 125. Inlet main failures Can explain surprise low-water alarms
  126. 126. Fix air entrainment with baffles
  127. 127. Fix vortexing with proper pump spacing
  128. 128. Fix vortexing with added submergence
  129. 129. Problem #10: Inattention to safety
  130. 130. Safety isn't the problem - complacency is
  131. 131. Safety mentality always starts at the top
  132. 132. Nobody will watch out for your safety like you
  133. 133. You are not paid enough to risk life and limb
  134. 134. Ask: Is there a safer way?
  135. 135. A path to fewer hassles
  136. 136. It starts with recordkeeping
  137. 137. You're probably a hands-on person
  138. 138. You need the help of numbers people
  139. 139. Appeal to their way of thinking, not your own
  140. 140. Your inconveniences mean little to them
  141. 141. Learn to quantify your troubles Make pumping hassles a matter of dollars and cents
  142. 142. Take gauge readings and record them
  143. 143. Document spills and leaks...look for patterns
  144. 144. Record smells, sounds, temperatures
  145. 145. Get comfortable with spreadsheets
  146. 146. Officials and managers need hard evidence
  147. 147. Engineers need actionable observations
  148. 148. Equipment suppliers need feedback
  149. 149. Spare parts Availability of replacement pumps, motors, and parts is essential to maintenance
  150. 150. Spare parts Your shelf + local supplier's shelf + manufacturer's shelf
  151. 151. Don't put off maintenance and improvements Deferred maintenance costs aren't any less real just because we defer them
  152. 152. Compounding interest can make you rich
  153. 153. Deferred maintenance costs compound, too
  154. 154. Compounding costs can ruin a great system  Decide what you need  Measure the total costs  Document  Quantify, quantify, quantify  Make the case to get what you need to serve the public
  155. 155. Questions?  Thank you for coming!  Brian Gongol | DJ Gongol & Associates  515-223-4144 | info@djgongol.com | @djgongol
  156. 156. References  All images are original work by and copyright reserved to Brian Gongol  Pump curves used courtesy of the Gorman-Rupp Company

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