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Millwright Block 3 > Compressors > Flashcards

Compressors Flashcards

1
Q

What is the biggest concern with compressors?

A

Moisture

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2
Q

What is the most important thing on a Compressor / pneumatic system?

A

Volume of air

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3
Q

How are compressors classified??

A

Principle operations
Their motion

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4
Q

What is maximum pressure control.?

A

It prevents further compression one the required maximum is reached

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5
Q

What is an unloading device?

A

’ It consist of a set of fingers controlled by a pilot line from the systems air pressure

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6
Q

What are other methods to controlling the maximum air pressure of the Compressor?

A

Throttling the air intake
Using an variable speed drive
Using an pressure switch

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7
Q

Where would axial compressors be used?

A

Gas turbines

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8
Q

What are some benefits of an axial compressor?

A

High efficiency
Large Mass of flow capacity

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9
Q

What are 2 disadvantages of axial compressors?

A

Large pressure rising make them complex
Expensive

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10
Q

What is the purpose of a diahgram in a compressor ?

A

Prevent short cycling of air
Stop air from leaking from one side to the other

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11
Q

What are a few things lubricants must have (4)?

A

Excellent protection from rust and corrosion
Good demulsibility to shed water that enters the lube system
Prevention of acidity, sludge, deposit formation
Good foam control

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12
Q

What does BDC stand for?

A

Bottom dead centre

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13
Q

What style of piston rings ave found in both single-acting and double acting compressors?

A

Compressor rings

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14
Q

What are the three measurements that must be made on an overhauled channel value?

A

End clearance
Side clearance
Lift

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15
Q

What value is best suited for high speed services?
A. Feather
B. Channel value
C. Dampenend disc value
D. Concentric Ring value

A

C. Dampenend disc valve

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16
Q

Why is it a mistake to clean the value before inspecting it?

A

Because you can erase valuable clues such as leaks, and foreign parts

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17
Q

Why should you rotate the compressor at least once prior to starting up?

A

Ensuring nothing is hitting, binding or rubbing

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18
Q

A pressure differential causes this component to open/ close?

A

Valves

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19
Q

What is the primary function of the distance piece?

A

Prevent contamination between the cylinder gases and the oil from the crankcase

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20
Q

What Motion does a crankshaft convert of the prime mover? What then does a prime mover convent to?

A

Rotary
Reciprocating

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21
Q

Where are intercoolers located?

A

Between stages

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22
Q

Where are aftercoolers located?

A

After final stage of compression

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23
Q

When are reciprocating compressors used?

A

When High Compression ratios are required per stage with high flow rates and where process fluid is relatively dry

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24
Q

What are the two classifications of industrial compresses

A

Intermittent (Pd)
continuous flow( c )

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25
Q

What is a stator?

A

Comprised of a series of blades attacked to the casing walls

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26
Q

What is the purpose of a shroud?

A

Provide support for the longer stator vanes at the inlet to provide a gas seal between the rotating and stationary.

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27
Q

What does VVCP stand for?

A

Variable volume clearance pocket

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28
Q

When measuring a cylinder bore to check for wear , it is important to measure in the area of?

A

Ring travel

29
Q

Compared to a dry liner, a wet liner would have thicker or thinner wall thickness?

A

Thicker

30
Q

What is the function of Rod packing?

A

To prevent leakage from the cylinder along the piston Rod.

31
Q

What type of cut does a pressure breaker have?

A

Radial cut

32
Q

The Dots on piston rings, do they go up or down? (Block test)

A

They go up

33
Q

How could you make an Compressor more efficient?

A

Preheating air

34
Q

Why is a jog or bump test performed on a compressor?

A

To check rotation

35
Q

What will happen is a servo value is stuck in the closed position?

A

The unloader value never gets an oil signal to tell it to close so the Compressor is always trying to supply the full volume of air

36
Q

How is the operation of the control system set at any specific pressure?

A

Spring setting on the servo valve

37
Q

What component contains the inlet/outlet ports in a wet sliding vane compressor?

A

Stator

38
Q

Where is the servo valve located in a sliding vane compressor?

A

Oil reservoir

39
Q

Where is the unloader valve located?

A

After inlet hose but before the rotor

40
Q

Which valve May be used to unload the compressor for ease of starting?

A

Safety relief valve

41
Q

What does it mean for a compressor to have a built -in pressure ratio?

A

That its not adjustable

42
Q

What is the only major moving part in a sliding vane compressor?

A

Rotor assembly

43
Q

What are the two main categories of screw compressors

A

Wet screw
Dry screw

44
Q

Which rotor is the driver on a screw compressed

A

Male rotor

45
Q

What 4 things determine the capacity of a screw compressor?

A

Rotor length
Diameter
Lobe (flute) design
Speed

46
Q

What determines the discharge pressure of a screw compressor?

A

Length of the compression path along the lobes and flutes but for most part determine by the location of the inlet and/or discharge ports

47
Q

Which component does the air enter after leaving the oil-flooded Compressor?

A

Separator

48
Q

Which valve operates like the thermostat in a motor vehicle ?

A

Thermal mixing valve

49
Q

What is a screw compressors simplest type of control system?

A

Online/offline

50
Q

What does VFD stand for?

A

Variable frequency drive

51
Q

When being proper maintained , how many hours in between majoroverhauls can the Compressor experience?

A

80,000 to 100,000 hrs

52
Q

What could result in a compressor when there is a stuck blowdown valve?

A

Low air delivery

53
Q

What is the most common cause of high discharge air temperature in a liquid cooled compressor?

A

A restriction of flow of the cooling air through the radiator

54
Q

What is pressure ratio (PR)?

A

Is the ratio of the absolute Compressor incoming air pressure to the absolute compressor discharge pressure.

55
Q

What does A pressure valve do?

A

Keeps air from back flowing
Males sure all systems are running before adding pressure

56
Q

At what pressure with the valve stay open? (Sliding vane compressor)?

A

60Psi

57
Q

What does aux mean?

A

Nice to have

58
Q

What does Ann mean?

A

Must have

59
Q

What do oil return valves do?

A

Prevents hydraulic locking
Prevent pump from being over pressurized

60
Q

What is another name for vacuum pump ?

A

Negative pressure (below 14.7)

61
Q

What does A vacuum relief valve do?

A

Prevent a vacuum buildup within the rotor area and to prevent the vanes to become unstable and chatter or bounce around

62
Q

How do lobe/roots blowers move air?

A

One moved an fixed volume of air from one side of the blower to the other as the lobes rotate

63
Q

When are timing gears used?

A

Dry applications

64
Q

Why use three lobe blowers? (4)

A

Increase efficient
Less slip
Less noise
less leakage

65
Q

What is an unloading device?

A

Allows the drive to run with the least hp demand when it reaches maximum fair pressure

66
Q

What does adiabatic mean?

A

An process or condition where Heat dosent leave or enter a system

67
Q

What does ISOthermal mean?

A

Involving or containing a constant temperature

68
Q

What is the purpose of an diagram in a compressor?

A

Prevent short cycling
Stop air from leaking from one side to the other

Millwright Block 3 (11 decks)

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