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Course L > Fourth Year - Block D Water Service and Distribution[][][][][][][][][][][][][][][][][][][][][][][] > Flashcards

Fourth Year - Block D Water Service and Distribution[][][][][][][][][][][][][][][][][][][][][][][] Flashcards

1
Q

How does a centrifugal pump work?

A

Taking water in the center (eye) of the pump, it then throws it to the outside of the impellar by way of the vanes. At this point the water has increased in speed. The water is then thrown into the volute where the water is slowed down and the pressure is created.

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2
Q

What happens when you increase the length of the impellars?

A

The pressure increases.

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3
Q

What happens when you increase the width of the impellars?

A

The volume increases.

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4
Q

What would happen if you put two centrifugal pumps in series?

A

Increased pressure.

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5
Q

What would happen if you put centrifugal pumps in parallel?

A

Increased volume.

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6
Q

What would happen if the space between the impellar and the volute (diffuser) is too great on a pump?

A

Decrease in efficiency.

(Pump has less of an ability to create a vacuum).

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7
Q

What is the definition of a shallow well?

A

Water is 25 feet or less below the pump.

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8
Q

What is the definition of a deep well?

A

Water is greater than 25 feet below the pump.

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9
Q

What is drawdown level?

A

The level which the water level drops once the pump kicks on.

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10
Q

What is the most common type of shallow well pump?

A

Jet pump.

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11
Q

What is a jet pump?

A

Jet assembly is part of the pump.

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12
Q

What is the difference between a shallow well jet pump and a deep well jet pump?

A

Location of the jet assembly.

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13
Q

What is the THEORETICAL suction lift of a shallow well jet pump?

A

33.9 feet.

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14
Q

What is the practical lift of a shallow well jet pump?

A

25 feet.

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15
Q

How many pipes run into a shallow well jet pump installation?

A

One pipe - suction line.

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16
Q

There are two pipes that run down into the water in a deep well jet pump installation. What would the sizes typically be? What are the names of the two pipes?

A

Drive line.

Suction line.

The suction line is usually one size bigger than the drive line.

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17
Q

A deep well jet pump diverts some of the water that it has drawn up from the well right back down into the well. What is the name of the valve that adjusts how much water goes to the house, and how much goes back down into the well?

A

Control valve.

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18
Q

What would need adjustment if you needed to lower your jet assembly of a “deep well” jet pump?

A

Control valve.

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19
Q

Referring to the figure below, what is this a picture of?

A

Foot valve.

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20
Q

What is the function of a foot valve?

A

Screen for the check valve and suction line.

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21
Q

Referring to the figure below, what is it a picture of?

A

Pitless adaptor.

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22
Q

What is a pitless adaptor used for?

A

To prevent the suction line from freezing.

23
Q

How is a pitless adaptor attached to the well casing?

A

Saddle fitting.

24
Q

If a pump created 30 psi, how high could it lift water?

A

30 psi x 2.31 feet of head / psi = 69.3 feet.

25
Q

What is it called when the pump starts and stops frequently?

A

Cycling.

26
Q

How can you prevent a pump from cycling?

A

Add a pressure tank and a pressure switch.

27
Q

Referring to the figure below, the pictures are of a pressure switch in a water pump system. What is the function of the pressure switch?

A

Maintains pressure in the system.

28
Q

What is the typical cut-in and cut-out pressures of a pressure switch?

A

20 psi differential between cut in and cut out.

29
Q

What should the pressure in a diaphram pressure tank be charged to?

A

2-3 psi below the cut-in point of the pressure switch.

30
Q

What is cavitation?

A

The formation and accumulation of bubbles around a pump impeller.

31
Q

What are the three steps which must be taken before starting a pump?

A

Primed.

Rotation (Bumping).

Valve positions[][][]]

32
Q

When would you use a submersible pump?

A

When the water has to be lifted more than 25 feet.

33
Q

How does a submersible pump create enough pressure to move water long vertical distances?

A

Impellars or stages placed in series.

(Each stage jumps the pressure up a few psi).

34
Q

What should be installed in the discharge line from a submersible pump to prevent the line from losing water?

A

Check valves.

35
Q

Referring to the figure below, what is it a picture of?

A

Torque arrester.

36
Q

What is the function of a torque arrester?

A

To absorb motor starting torque.

(Installed directly above submersible pump).

37
Q

What is the function of an air volume control? (used in a conventional expansion tank - no diaphram).

A. To maintain proper amount of water in the pressure tank.

B. To maintain proper amount of air in the pressure tank[][][]]

C. To maintain the correct amount of pressure in the system.

D. To activate the pump motor when all air is exhausted from the tank.

A

B. To maintain proper amount of air in the pressure tank.

38
Q

What type of pump is a “booster” pump in a highrise building?

A

Centrifugal pump.

39
Q

When is a booster pump needed?

A

When the building needs to be pumped higher than the city pressure (High demand)

40
Q

Why are centrifugal pump suction lines installed with positive grade from the well to the pump inlet?

A. To allow water from the pump to drain back to the well to prevent freezing.

B. To keep positive pressure on the foot valve to ensure it will stay closed[][][][]

C. For better air elimination when priming[][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][]

D. Water flow to pump impellar is more laminar, helps to prevent cavitation[][][]

A

C. For better air elimination when priming.

41
Q

If a pump has a total head of 230 feet and a suction head of 45 feet, what would be the discharge head?

A

Total head = suction head + discharge feet.

42
Q

The discharge side of a jet pump has a polyethylene water service pipe connected to it. How would the polyethylene pipe be attached to the outlet of the pump?

A

Two gear clamps in opposite directions.

43
Q

What phase are large high amperage motors usually supplied with?

A

Three phase.

44
Q

What would be the colours of a 120 volt three wire cable?

A

Black, red and white.

45
Q

How would you support a 400 foot submersible pump?

A. A cable from the pump to the cap.

B. A cable from the horizontal piping to a beam.

C. A cable from the horizontal piping to the casing.

D. It may be supported by the pitless adaptor[][][][][]]

A

A. A cable from the pump to the cap.

46
Q

In what water source would you most likely find iron (ferrous material)?

A. Deep well.

B. Shallow well.

C. River[][][][][][][]

D. Pond[][][][][][][]

A

A. Deep well.

47
Q

What must never be installed on the suction side of a piston pump?

A

Air vent.

48
Q

What is the most likely cause of low production from an existing jet-pump?

A

A leak has developed in the suction line.

49
Q

What would be the result of a leaky foot valve on a jet pump assembly?

A

Loss of prime in the pump.

50
Q

Which of the following tests could be used to determine if a recirculating pump is experiencing cavitation?

A. Voltage.

B. Pressure difference between the inlet and outlet.

C. Temperature difference between the inlet and the outlet.

D. Heat of the pump motor[][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][]

A

B. Pressure difference between the inlet and outlet.

51
Q

Vibration in a base-mounted pump is commonly caused by?

A

Misalignment between motor and pump shaft / Cavitation.

52
Q

If a pump is experiencing excessive vibration and noise, what might this be an indication of?

A

Misalignment between motor and pump shaft / Cavitation.

53
Q

A pneumatic tank is undersized. What would occur?

A

The pump would cycle.

Course L (30 decks)

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