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Centrifugal Pumps > Chad's > Flashcards

Chad's Flashcards

1
Q

What does the first number on the C-pump reference number indicate?

A

diameter of the discharge port in inches

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2
Q

What does the second number on the C-pump reference number indicate?

A

diameter of the suction port in inches

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3
Q

How does a C-pump work?

A

It employs a centrifugal force to develop pressure change to move a liquid.

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4
Q

What are the steps of the function of the C-pump?

A

When the pump is full of fluid and the impeller begins rotating, the fluid follows the impeller blades. As the impeller speed increases, the centrifugal force throws the fluid toward the outer edge of the impeller blade.

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5
Q

What happens when the impeller moves faster?

A

The faster the fluid moves outward and the greater the flow rate.

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6
Q

What is necessary for a C-pump to move fluid?

A

It must be full of fluid

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7
Q

Pumps convert _____ energy from an engine or electric motor into ______ energy by pushing fluid into the system

A
  1. mechanical

2. hydraulic

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8
Q

What are the two main families of pumps?

A
  1. positive displacement pumps

2. non-positive displacement pumps

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9
Q

What defines a positive displacement pump?

A

Whatever enters the pump inlet is forced out the outlet port

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10
Q

How do positive displacement pumps add energy?

A

by increasing the pressure on the fluid in the pump

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11
Q

A positive displacement pump delivers a specific amount of _______, revolution, or cycle to the system.

A

fluid per stroke

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12
Q

How is pump output on a positive displacement pump?

A

constant, regardless of pressure, with the exemption of changes in efficiency

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13
Q

What are the 3 best know positive displacement pumps?

A
  1. gear pumps
  2. vane pumps
  3. piston pumps
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14
Q

What defines a non positive displacement pump?

A

Do not have a positive seal between the inlet and outlet ports.

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15
Q

For non-positive displacement pumps, what are pressure capabilities a function of?

A

drive speed

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16
Q

For a non-positive displacement pump, what happens to output as resistance is increased?

A

output is reduced

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17
Q

When are non-positive displacement pumps mainly used?

A

fluid transfer in systems where the only resistance is created by weight of the fluid and by friction

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18
Q

Non-positive displacement pumps ____ energy by _____ the speed of the fluid inside the pump

A

add

increasing

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19
Q

What are the 7 main components of a centrifugal pump?

A
  1. casing or volute
  2. impeller and wear plates
  3. shaft
  4. bearings
  5. bearings frame and stuffing box
  6. seals or packing
  7. power source
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20
Q

What is the C-pump casing/housing called?

A

Volute

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21
Q

What does the volute convert the velocity energy into?

A

pressure

and also gives the fluid direction.

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22
Q

What two factors determine volute design?

A
  1. maximum output rates and pressures

2. sense of pump rotation or the intended rotation direction

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23
Q

How can the rotation of the volute be determined?

A

by watching the direction of rotation of the input shaft.

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24
Q

What are volute frames typically made of?

A

cast iron
therefore they should never be welded or brazed because the heat will call the volute to become distorted, warped, or cracked.

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25
Q

Volute Casing:Flowrate

Volute Casing:Pressure

A

directly

indirectly

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26
Q

What is the impeller?

A
  1. the rotating element in the centrifugal pump through with liquid passes.
  2. energy is imparted to the liquid in the impeller
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27
Q

What are the 3 types of impellers?

A
  1. open
  2. semi-open
  3. closed
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28
Q

What is an example of an open impeller?

A

RA 4X5

RA 5X6

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29
Q

What types of fluids do open impellers typically move?

A

dirty

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30
Q

What flow rates do open impellers have?

A

high

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31
Q

What discharge pressures do open impellers have?

A

Low

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32
Q

What is an example of a closed impeller?

A

RB 2X3

Guinard

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33
Q

What type of fluid do closed impellers move?

A

Clean

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34
Q

What flow rate to closed impellers typically have?

A

Low

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35
Q

What discharge rates do closed impellers typically have?

A

High

36
Q

What 3 ways can the direction of impeller rotation be changed?

A
  1. reversing the volute
  2. installing the opposite impeller
  3. . switching the hydraulic lines to the motor
37
Q

What is the purpose of wear plates?

A

provide a wear surface and a seal between the casing and the impeller.

38
Q

Where are the wear plates located?

A

on either side of the impeller and are generally solid steel plates

39
Q

What should be replaced when installing a new impeller?

A

wear plates

40
Q

What is the correct clearance between the impeller and the wear plates?

A

1/16 inch

41
Q

True or False. Wear rings serve the same function as wear plates

A

True

42
Q

Wear rings are used in centrifugals that contain ______ impellers.

A

closed

such as RB 2X3X11

43
Q

What are wear rings typically made of?

A

brass

44
Q

What is the role of the centrifugal pump shaft?

A

supports the impeller and is itself supported by bearings

45
Q

The shaft transmits the torque from a _______ source to the _______ where it is subject to radial, axial, and torque loads.

A

power source

impeller

46
Q

True or False. Radial loads are due to the impeller weight and pressure differences around the impeller when it is moving

A

True

47
Q

What is the function of the bearing?

A

supports the shaft

48
Q

What happens if the shaft is not supported and held with a precision?

A

The impeller will touch the casing and the packing will have a shorter life span.

49
Q

Where is the seal or packing contained in the stuffing box located?

A

between the stationary casing casing and the rotating shaft.

50
Q

What is the role of the stuffing box and packing material of a c-pump?

A

provide an area to seal against leakage from the pump and along the shaft.

51
Q

The packing material must counter ______

A

the effects of the fluid trying to escape along the shaft when it is being pumped at pressure.

52
Q

What are the 3 things that packing material must have?

A
  1. a low coefficient of friction
  2. an absence of abrasive effect on the shaft
  3. an ability to prevent excessive leakage
53
Q

What are the two main types of packing materials?

A
  1. “jam-type” (used for self-lubricating pumps)

2. rubber oil seals known as”automatic/mechanical type”

54
Q

Describe “jam-type”

A

Rope packing that is jammed into the stuffing box and adjusted periodically by tightening the nuts on a gland to preserve its sealing ability

55
Q

T or F. Rope packing in a c-pump acts like a seal around the moving shaft, but only to the extent that it throttles leakage.

A

True

56
Q

Where does lubrication come from in rope packing?

A

a slight leak through the packing or, in emergencies, from a saturant in the packing itself.

57
Q

What happens if the packing is dry?

A

it will start to run hot, harden, and score the shaft.

58
Q

What happens if the packing is over-tightened?

A

the packing will soon burn up and score the shaft, so it is important to pack the stuffing box properly

59
Q

Which ring does most of the work in rope packing?

A

The ring next to the gland in jam-type packing does most of the work because the mechanical pressure on the gland is greater than the friction along the rod.

60
Q

What are the 3 common rope packing ring materials?

A
  1. asbestos rope
  2. teflon-coated rope
  3. graphite-coated rope
61
Q

How do the mechanical seals work?

A

liquid pressure in the seal chamber force the mating faces together and provide a thin film of lubricant between them.

62
Q

Which types of pumps use mechanical seals?

A

RA 4X5
RA 5X6
RB 2X3X11

63
Q

True or False. Neither “jam type” seals or the oil seals should ever be over-tightened.

A

True

64
Q

3 types of lubrication

A
  1. self-lubricated
  2. oil
  3. grease
65
Q

What does the method of lubricating the packing largely depend on?

A

the nature of the liquid being pumped as well as the pressure in the stuffing box

66
Q

What happens when the pumping stuffing box pressure is above the atmospheric pressure?

A

the pumped liquid itself will lubricate the packing. The pumped liquid must be allowed to leak or flow through the stuffing box to cool the packing.

67
Q

What are examples of self-lubricated systems?

A

RB 2X3 and the LPM pumps

68
Q

What is cavitation?

A

a

69
Q

True or false. For pumps that have a lower discharge pressure, an enclosed lubrication system is needed to help prevent cavitation

A

True

70
Q

Which is the best lubrication system?

A

oil-lubricated systems

71
Q

What two things are extremely detrimental to packing?

A
  1. inadequate lubrication

2. heat generation

72
Q

True or false. An air-operated pump (Alemite pump) delivers lubricating oil to a divider block which in turn delivers oil equally to each packing set.

A

True

73
Q

Which pumps use oil lubrication systems or air over oil packing lube systems

A

RA 4x5 and RA 5x6

74
Q

Grease lubrication

A

not very efficient. used for pumps with a high discharge rate and low pressure. example is the RB 10x12

75
Q

What are the 4 main power sources for centrifugal pumps?

A
  1. Diesel Drives
  2. Electric Drives
  3. Power Take-Off (PT0)
76
Q

Which type of pumps typically use diesel-driven C-pumps?

A

small pressurizer skids and blenders

77
Q

Which type of C-pumps use electric drives?

A

Offshore RMX and Batch Mixers (RA45-RA56)

78
Q

What are power take-offs?

A

drive mechanisms coupled directly from the transmission of the engine

79
Q

Which type of C-pumps typically use hydraulic drives?

A

cement pump units, recirculating mixers, and batch mixers (RA45-RA56)

80
Q

What centrifugal pumps are used by Schlumberger?

A

RB 2x3, RA 4x5, RA5x6, 10x12

81
Q

Which pumps use open impellers?

A

RA45
RA56
LaBour 5x6

82
Q

What is the RA45 pump used for?

A

pressuring and make-up pump

*used for both sand and cement pumping operations

83
Q

What type of seals do the RA45 pumps use?

A

mechanical oil seals

84
Q

What is the main application of the LaBour Pump 5x6

A

a Tornado mixer

85
Q

What are the pumps with closed impellers used for?

A

low pressure mixing pumps

Centrifugal Pumps (2 decks)

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