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Machinist Mate 3 & 2 > Test 9: A/C And Compressed Air Systems > Flashcards

Test 9: A/C And Compressed Air Systems Flashcards

1
Q

What are the functions of air conditioning?

A

Prevents deterioration of ammunition in storage spaces
Mains temps. At specified levels
Prevents excessive pressure buildup in container in gas storage spaces.

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2
Q

Definition of dew point of air:

A

The temperature at which any increase in temperature will cause moisture to vaporize

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3
Q

The relative humidity of air is the ratio between the actual amount of water vapor in a sample of air and

A

The amount of water vapor the sample would hold if it were saturated.

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4
Q

The deciding factor in human comfort is the relative humidity.
True or false

A

True

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5
Q

It is possible to feel more comfortable at 90F than at 70F

True or false

A

True

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6
Q

What is your body’s continuous source of heat?

A

Physiological processes within the body

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7
Q

What is the best overall range of relative humidity for human comfort and health?

A

30% to 70%

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8
Q

In the duct systems of navy ships, axial flow fans are used instead of centrifugal fans for what reason?

A

Require less space for installation

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9
Q

Onboard navy ships, what fan(s) are used primarily to exhaust explosive or hot gases?

A

Centrifugal

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10
Q

Vane-axial ventilating fans are operated with air ducts open for what reason?

A

The motor will not overheat

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11
Q

Excess water accumulated in heavy seas is automatically sealed out of waterproof ventilators by what means?

A

The weight of the water in the bucket

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12
Q

In chilled water circulating systems, the type of primary refrigerant depends on the size and type of the compressor.
True or false

A

True

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13
Q

Where is the heat removed from the secondary refrigerant of a vapor compression unit?

A

Water chiller

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14
Q

In a centrifugal refrigeration plant, what valve releases the refrigerant to the chiller?

A

Float valve

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15
Q

The lithium bromide unit operates on the absorption cycle. What is used as the primary refrigerant?

A

Water

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16
Q

When there is a 29.9-inch vacuum in the container of a lithium bromide absorption unit, what is the lowest temperature at which water will boil?

A

35F

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17
Q

In a lithium bromide absorption unit, the regeneration heat exchanger performs what function on the lithium bromide?

A

It preheats the weak and cools the strong solution.

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18
Q

What is the purpose of the collection tray on the spot cooler?

A

To collect condensation from the air around the cooling coils

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19
Q

Dirt should be kept out of a ventilation system for what reason?

A

Restricts airflow and creates a fire hazard

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20
Q

Which maintenance action is proper for air-conditioning equipment?

A

After washing, oil the filters with filter oil

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21
Q

Aboard navy ships, compressed air is used for which of the following purposes?

A

Operating pneumatic tools
Starting Diesel engines
Charging and firing torpedoes

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22
Q

A reciprocating air compressor is generally selected for what capacity requirements?

A

800 cfm and 5,000 psi

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23
Q

What is the usual source of power for operating air compressors aboard ship?

A

Steam turbines and electric motors

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24
Q

What device is generally used to connect the source of power to an air compressor when the speed of the driving unit and compressor is the same?

A

Flexible coupling

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25
Q

Which of the following is the classification of a medium-pressure air compressor?

A

Two-stage, vertical, duplex single-acting with a discharge of 151 to 1,000 psi

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26
Q

What cylinder arrangement is used in two-stage, W-type air compressors?

A

Two cylinders for the first stage and one cylinder for the second stage.

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27
Q

A piston makes what total number of strokes during each operating cycle of a single-acting air compressor?

A

Two

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28
Q

Which parts are included in the compressing elements of an air compressor?

A

Air valves, cylinders, and pistons. Unloaders are not part of the compressing elements

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29
Q

The operation of the automatic valves of an air compressor is initiated by what means?

A

An air pressure differential pressure

30
Q

What device is used to lubricate the high-pressure air compressor cylinders?

A

A compressor oil pump

31
Q

Which of the following means is/are used to cool most high- and medium-pressure air compressors?

A

Fresh water or sea water

32
Q

The cylinders and heads of some shipboard air compressors are made from bronze alloy for what reason?

A

To minimize corrosion

33
Q

What is the function of the intercoolers of an air compressor?

A

Remove heat generated during compression and to condense existing vapor

34
Q

The quantity of water that passes through the oil cooler can’t be regulated without changing the quantity that passes through the intercoolers.
True or false

A

False.

35
Q

What is the purpose of using baffles in tube-type water cooled intercoolers?

A

To deflect air or water passing through the cooler

36
Q

The control system for an electrically driven reciprocating air compressor will automatically stop the compressor when the pressure in the receiver causes what action?

A

The pressure switch to close

37
Q

The automatic temperature shutdown device of a high-pressure reciprocating air compressor stops the compressor under what condition?

A

When the cooling water temperature rises above a preset limit

38
Q

In rotary-type centrifugal compressors, air is compressed by which of the following forces?

A

Centrifugal force

39
Q

Which of the following is the purpose of the air receiver in an air compressor?

A

To minimize pressure variations

40
Q

What system is supplied by non-vital air?

A

Laundry equipment
Air hose connection
Tank level indicator systems

41
Q

What type of compressor supplies air to the prairie-masker system?

A

A turbo compressor

42
Q

When very high-pressure air is throttled to low pressure at a high flow rate, the throttling valve freezes. Which of the following is the reason for the valves freezing?

A

Venturi effect

43
Q

What is the cooling medium for oil-free compressor?

A

Freshwater

44
Q

What device controls the movement of the A-end of an electro-hydraulic speed gear

A

A tilt box

45
Q

The A-end hydraulic pump and B-end hydraulic motor combination provides rotary motion. What change is made in the hydraulic system to provide reciprocating motion?

A

The tilt box is placed in a neutral position

46
Q

When the ram is moving, oil is forced into one ram cylinder and out of the other cylinder to what destination?

A

Suction side of the main hydraulic pump

47
Q

Which device maintains hydraulic pressure in the ram-type electro-hydraulic steering gear?

A

A trick wheel

48
Q

If the remote steering systems fails, what device is used for local hydraulic control of the steering gear?

A

A trick wheel

49
Q

If electrical power is lost to the hydraulic pump motor, what device can be used to control the steering gear?

A

A hand pump

50
Q

Some electro-hydraulic anchor windlasses have two motors. One motor drives each of the pumps, which normally drives each of the pumps, which normally drives one wildcat. However, each pump can drive either wildcat with the use of what device?

A

A three-way plug, cock-type valve

51
Q

A windlass has been idle for several months. Before operating the windlass, what maintenance actions should you perform?

A

Adjust the brake

52
Q

What type of winch is used to hoist aircraft aboard the ship?

A

Electro hydraulic

53
Q

The horizontally mounted drum of an electro-hydraulic winch is connected to the shaft by what device?

A

A clutch

54
Q

Electric capstans are usually reversible. Those powered by D.C. Motors usually have what total number of speeds in either direction of rotation?

A

A

55
Q

The boom of a crane is controlled by what means?

A

A

56
Q

Fouling of the hoisting ropes is prevented by what means?

A

A

57
Q

The delicate control often required to handle loads with a crane is usually provided by what means?

A

A

58
Q

On a crane, what device is provided to hold the load when electric power fails?

A

A

59
Q

What device finds and retains the neutral position of the A-end hydraulic pump on a crane.

A

A

60
Q

When a crane is used to raise light loads, the cable has a tendency to develop slack when hoisting is started. What means is used to prevent slack?

A

A

61
Q

CV class aircraft carriers are equipped with airplane elevators that have what max lifting capacity?

A

A

62
Q

In the closed hydraulic system of an elctro-hydraulic power plant, nitrogen is used with oil instead of air for which of the following reasons?

A

A

63
Q

An electro1hydraulic elevator is raised by high-pressure oil acting directly against what component?

A

A

64
Q

On modem deck-edge elevators, what built-in safety feature limits the damage caused by the possible breaking of all hoisting cables on one side of the elevator?

A

A

65
Q

Power conveyors are configured either vertically or horizontally.
True or false

A

A

66
Q

Conveyors are used to handle what kind of supplies?

A

A

67
Q

While loading a vertical conveyor, what is the position of the load-unload device?

A

A

68
Q

What is the purpose of the interlock switch on a vertical package conveyor?

A

A

69
Q

What safety precautions must you take to ensure accident-free operation of horizontal conveyors?

A

A

70
Q

The final rinse in a double tank dishwasher is activated by what means?

A

A

71
Q

In the double tank dishwashing machine, the final rinse is controlled by an adjustable automatic steam-mixing valve that maintains what temperature ranges?

A

A

72
Q

The rinse tank of a double tank dishwashing machine contains a thermostatically operated switch that prevents machine operation if the rinse water drops below what temperature?

A

A

Machinist Mate 3 & 2 (6 decks)

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