The document discusses different types of pumps and priming. It defines priming as evacuating air from a pump and supplying it with liquid. Pumps can be priming-assisted, requiring an external mechanism to displace air, or self-priming, able to create their own vacuum. Self-priming pumps are preferable for safety and require less maintenance. Factors that can limit priming include atmospheric pressure, liquid characteristics like vapor pressure, total dynamic suction lift, and wear of pump components over time. Troubleshooting failed priming may involve addressing air entrainment, binding, excessive suction lift, or liquid property changes.

1. I’ve Had the
Prime of My Life
Brian Gongol
DJ Gongol & Associates, Inc.
August 1, 2022
Kirkwood Annual Wastewater Conference
Cedar Rapids, Iowa

2. Why did Jack and Jill go to the top of the hill?

3. It must have been a
great artesian well

4. If you’re above the water,
then you have to prime
If you’re above the water,
then you have to prime

5. Who here prefers to drink from a straw?

6. Certain
limitations
apply

7. If the straw develops a
crack, it stops working

8. If your milkshake is too thick,
it won’t flow

9. You can’t drink
from two
stories up

10. You “suck” on
a straw…
but you’re
really just
priming your
drink

11. So, what’s the definition of priming?
So, what’s the definition of priming?
Evacuating the air from a pump
and supplying it with pumpable liquid
Evacuating the air from a pump
and supplying it with pumpable liquid

12. Priming is by default when pumps are
submerged or on flooded suction lines

13. Why bother
priming a pump?

14. Getting water to the
pump is usually
safer than taking
the pump to the
water

15. Priming can also be more practical

16. Pumping from a storm basin
over a levee

17. Pumping out of
basements and
other enclosed
areas where
engines are unsafe

18. Sites with limited
wetwell capacity

19. Installations with
constrained site
conditions (rocks,
rivers, development,
underground utilities)

20. When sending water downhill, you siphon

21. When sending water
uphill, you need a pump

22. Now, a helpful reminder:
A pump is not a fan

23. Pumps are for
fluids in a liquid
state (or very
close to it)

24. A pump can either prime by itself or with help

25. So, how would we define priming assistance?

26. Have you ever siphoned gas from a car’s tank?

27. Assistant #1: Vacuum pumps

28. Assistant #2:
Compressors

29. Assistant #3:
Venturis

30. The priming
bulb on your
snowblower is
classic priming
assistance

31. When an external mechanism is required to displace
the air with liquid, the pump is priming-assisted

32. So, how would we define self-priming?

33. Approach #1: Priming by positive displacement
(like peristaltic pumps)

34. Approach #2:
Priming via an integrated compressor stage

35. Approach #3:
Priming with centrifugal motion and air stripping

36. This is where the “liquid state or something very
close to it” factors in

37. The impeller mixes the air with water to create a
pumpable fluid

38. Which is why the air
needs a way out

39. Even a pump on a flooded suction may need a
means of air release

40. When a pump can create its own vacuum
condition, it is self-priming (just add water)

41. “Self-priming” can be a
misleading definition
So:
Know your reprime

42. Some pumps
preserve prime
with internal
suction check
valves

43. This is like
holding
your thumb
over the
end of a
drinking
straw

44. Some pumps use foot
valves to keep the
suction line from
draining out

45. Make water do the climbing, not the operators

46. Automatic-repriming pumps
have to be big because of
siphoning

47. A pump that can reprime itself
without a helper valve is
“self-priming with automatic
unattended repriming”

48. Two paths to a suction lift:
Automatic unattended repriming vs. priming-assisted

49. Both types can be
engine-driven

50. Engine drives are a big
advantage on construction sites

51. Prime-assisted pumps are well-suited to construction
sites, less so for unattended lift stations

52. Priming assistance increases the
number of system components
• Vacuum pumps
• Priming chambers
• Compressors
• Venturis
• Sensors
• Switches

53. More components means higher odds of failure

54. A pump that reprimes itself automatically and
unassisted is best for permanent operations

55. QUIZ: A pump that creates its own vacuum is…
• [A] Priming-assisted
• [B] Automatic-siphoning
• [C] Self-priming

56. QUIZ: A pump that creates its own vacuum is…
• [A] Priming-assisted
• [B] Automatic-siphoning
• [C] Self-priming

57. So, what limits
priming (whether
assisted or not)?

58. Everything starts with
available atmospheric pressure

59. Low-pressure weather conditions

60. Pump speeds

61. NPSHr

62. Liquid
characteristics
• Vapor pressure
• Viscosity
• Solids

63. TDSL
Total
Dynamic
Suction
Lift

64. TDSL is why we
don’t like foot valves

65. Net NPSH must be positive
• Atmospheric pressure (adjusted for elevation)
- vapor pressure
- safety factor
- pump NPSHr
- TDSL (total dynamic suction lift)

66. NPSH issues are
at the heart of
many pumping
problems
(whether self-
priming or not)

67. Where TDSL
exceeds 25’,
consider recessing
(just add stairs)

68. QUIZ: What limits priming when pumping hot
water?
• [A] Vapor pressure
• [B] Atmospheric pressure
• [C] TDSL

69. QUIZ: What limits priming when pumping hot
water?
• [A] Vapor pressure
• [B] Atmospheric pressure
• [C] TDSL

70. When priming doesn’t work, what do you do?
Shoot the
trouble, not the
pump station

71. Air entrainment

72. Air entrainment is like
poking a hole in a
drinking straw

73. Air binding

74. Air binding
• Remember: Air will move
preferentially before water
• If you can’t get the air out, it
may block the water
• This can affect flooded-
suction and submersible
pumps, too

75. Excessive TDSL

76. Excessive
TDSL can
come from
static heads
or from
friction
losses
Just like drinking a
milkshake that
collapses a flimsy
straw

77. Suction obstacles

78. Suction obstacles
• Rocks
• Mop heads
• Fatbergs
• “Flushable” wipes
• Turtles
• Muskrats
• Basketballs
• All pumps in
wastewater service
are susceptible

79. Liquid
factors
• Temperature
• Vapor pressure
• Viscosity

80. Shortfalls in
net NPSH
• Piping can change over time
• Buildup can increase friction losses
• Temperature or pressure changes

81. Equipment
wear or
changes IMPELLER DIAMETER LOSS
DUE TO WEAR
SPEED LOSSES DUE TO VFD
CHANGES OR V-BELT DRIVE
WEAR

82. Why are self-priming pumps worth extra effort?

83. Pump self-priming capacity contributes directly
to operator health and safety

84. If the pump is priming,
then you’re not climbing

85. Self-priming eliminates confined spaces

86. Self-priming
keeps
operators off
ladders

87. Self-priming keeps operators high and dry

88. Self-priming
keeps
dangerous
gases far away

89. Self-priming
increases
the number
of backup
options

90. Self-priming
keeps motors
out of the water

91. Pumps on dry land can be monitored for performance
and observed without lifting or climbing

92. Self-priming leads to faster clog removal

93. Self-priming
reduces fall risks
and lifting hazards

95. Remember, Jack and Jill
fell down the hill

96. Going to the water
is almost always
more dangerous
than making the
water come to you

97. Recap
Priming Priming assistance Self-priming Self-priming with
automatic unattended
repriming

98. Questions?
• Thanks for your time and
attention!
• This presentation can be
found at
gongol.net/presentations
• Brian Gongol
DJ Gongol & Associates
• 515-223-4144
• brian@gongol.net
• @djgongol on LinkedIn,
Twitter, and Facebook

99. Credits
• Artesian well diagram obtained from public domain:
https://www.usgs.gov/media/images/artesian-wellscan-
bring-water-land-surface-naturally
• OSHA violations list screen-captured from agency website:
https://www.osha.gov/top10citedstandards
• A limited number of stock images and icons were
automatically inserted by PowerPoint
• All other images (including all product-specific and project
site photos) are the original work of the author
• Copyright 2022 by Brian Gongol, all rights reserved