Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

4th Year Millwright > Dynamic Pumps > Flashcards

Dynamic Pumps Flashcards

1
Q

What are dynamic pumps also known as?

A

continuous flow, kinetic, centrifugal, or non-positive displacement

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the term used in regards to the ratio of the density of a substance to that of water?

A

specific gravity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the conversion from psi to kPa?

A

1 psi = 6.9 kPa

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is the formula used to determine pressure?

A

pressure = force/area

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is atmospheric pressure at sea level in psi?

A

14.7 psia (0 psig)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

How much atmospheric pressure is lost for every 1000 ft of elevation gained?

A

about .5 psi

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the head pressure of one foot head of water in psi?

A

0.433 psi

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

How much does a cubic foot of water weigh?

A

62.4 lbs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the difference between the discharge pressure and the suction pressure of a pump called?

A

differential pressure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the name for the pressure at which a liquid flashes into a vapour (boils) at a given temperature?

A

vapour pressure or boiling point

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What two components is the total head (total energy) in a system made up of?

A

head pressure (from the pressure acting upon the liquid) and velocity head (from the speed of the liquid)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the condition called where the supply reservoir is located below the pump?

A

suction lift

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is the vertical distance from the centre of the suction eye of the pump to the surface of the supply called?

A

static suction head

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

How can Net Positive Suction Head available (NPSHA) be expressed?

A

NPSHA = suction pressure (gauge) + atmospheric pressure - vapour pressure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is needed for a pump to overcome friction losses and increase the velocity of a fluid as per the pump manufacturer?

A

Net Positive Suction Head Required (NPSHR)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

How much greater should the NPSHA be than the NPSHR to prevent cavitation?

A

at least 10%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What are the 4 categories of dynamic pumps?

A

radial-flow centrifugal, axial-flow centrifugal, mixed flow, peripheral

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Which type of dynamic pump is most common in industry?

A

radial-flow centrifugal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is another name for an axial-flow pump? What are the pressure/flow properties of this type of pump?

A

propeller pump, relatively low discharge head, large flow

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What are the two types of peripheral pumps?

A

high-speed, regenerative turbine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Which type of pump has a bulbous, concentric casing with a close axial clearance between it and the impeller? This pump is also “self-priming”

A

regenerative turbine pump

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What are the 3 impeller designs available in a horizontal single-stage end suction pump?

A

open, semi-open, enclosed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What type of pump mounting is recommended for high temperature liquids?

A

centreline or pedestal mounted

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What type of shaft is used on a vertical column pit pump in abrasive service and why?

A

A cantilever shaft is used, which keeps the bearings out of the abrasive liquid.

25
What is a main advantage of using a wet pit?
The pump can be installed at a lower level increasing the NPHSA.
26
What is the advantage to a vertical single-stage end suction pump compared to a horizontal one?
It can be incorporated with the piping and in turn saves floor space.
27
What is a key characteristic in a single-stage double suction pump in regards to axial loads?
The double suction design results in opposing forces which balance out axial loads.
28
What happens to the pressure of a liquid in a multi-stage pump as it passes through the pump?
The pressure of the liquid increases progressively as it moves from one end of the pump to the other.
29
What prevents back pressure leakage in a multi-stage pump?
a diaphragm or stage piece
30
Which pump handles the highest pressures in the dynamic pump family (up to 6500 psi)?
multi-stage barrel pumps
31
What can occur if liquid vaporizes in a closed system?
cavitation
32
What pump characteristic does flow vary directly with?
impeller diameter
33
Where is the stripper in a regenerative turbine pump located?
between the suction and the discharge
34
What pump characteristic does the head produced vary with?
the square of the impeller diameter
35
What is the name for a shock wave from a sudden change in velocity in a pipe? What can cause this condition?
water hammer, can be caused by opening/closing valves, or starting/stopping a pump
36
What are some methods of counter-acting axial forces in a centrifugal pump?
balancing disc/drum or combination, pump out vanes, balance holes, thrust bearings
37
What impeller style would be best suited to handle fibrous slurries and abrasives?
semi-open
38
What are some possible causes of cavitation in a centrifugal pump?
a block or restriction in the suction, too much suction lift, high temperatures, high liquid viscosity
39
What is the purpose of a diffuser in a pump?
convert velocity to pressure, reduce radial bearing loads, direct flow (some multi-stage pumps)
40
What is the purpose of the volute casing?
to convert velocity energy into pressure energy of head
41
What are the 2 main types of pump shaft sealing devices?
mechanical seals, compression packing
42
How would an increase in wear ring clearance affect pump efficiency? At what point should wear rings be replaced?
it would reduce pump efficiency, wear rings should be replaced when clearance reaches 3 times original amount
43
What is the energy in a system due to the liquid's velocity known as?
velocity head
44
What is used to direct more flow to the pump impeller and help reduce the NPSHR?
inducer
45
Name 4 single stage end suction pump casing types
concentric, double volute, volute, diffuser
46
What is a "thrust pot"?
a bearing housing that helps support weight and thrust
47
What will happen when pressure exceeds the rated capacity of a centrifugal pump?
the impeller will slip in the liquid
48
How do you check for classic cavitation in a centrifugal pump?
throttle the discharge line
49
Where is the velocity of fluid flow greatest within the centrifugal pump?
near the tips of the impellers
50
Why is the double eye impeller not recommended for abrasive service?
because it requires 2 stuffing boxes
51
What is the most efficient impeller style?
the Francis vane impeller
52
How much is it possible to reduce the impeller of a volute pump before it affects pump efficiency? What about the impeller of a diffuser pump?
20% in a volute pump, 5-10% in a diffuser pump (depending on design)
53
What can happen to a pump if an object is stuck in the foot valve?
the pump won't prime
54
What's the minimum amount of straight pipe that should be between the elbow and the pump suction to prevent swirl or uneven flow?
10 diameters of straight pipe
55
What is considered the max shaft runout or radial movement (respectively) allowable in a dynamic pump?
0.003" (for either one)
56
Where are balance holes drilled through?
the rear shroud on the inside of the wear ring
57
Another name for a high speed impeller is:
paddlewheel impeller
58
How many suction inlet nozzles are there in a double suction single-stage pump?
one
59
What condition can occur when a check valve closes too quickly?
hydraulic slap

4th Year Millwright (11 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions