Test 9: A/C And Compressed Air Systems Flashcards
What are the functions of air conditioning?
Prevents deterioration of ammunition in storage spaces
Mains temps. At specified levels
Prevents excessive pressure buildup in container in gas storage spaces.
Definition of dew point of air:
The temperature at which any increase in temperature will cause moisture to vaporize
The relative humidity of air is the ratio between the actual amount of water vapor in a sample of air and
The amount of water vapor the sample would hold if it were saturated.
The deciding factor in human comfort is the relative humidity.
True or false
True
It is possible to feel more comfortable at 90F than at 70F
True or false
True
What is your body’s continuous source of heat?
Physiological processes within the body
What is the best overall range of relative humidity for human comfort and health?
30% to 70%
In the duct systems of navy ships, axial flow fans are used instead of centrifugal fans for what reason?
Require less space for installation
Onboard navy ships, what fan(s) are used primarily to exhaust explosive or hot gases?
Centrifugal
Vane-axial ventilating fans are operated with air ducts open for what reason?
The motor will not overheat
Excess water accumulated in heavy seas is automatically sealed out of waterproof ventilators by what means?
The weight of the water in the bucket
In chilled water circulating systems, the type of primary refrigerant depends on the size and type of the compressor.
True or false
True
Where is the heat removed from the secondary refrigerant of a vapor compression unit?
Water chiller
In a centrifugal refrigeration plant, what valve releases the refrigerant to the chiller?
Float valve
The lithium bromide unit operates on the absorption cycle. What is used as the primary refrigerant?
Water
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?
35F
In a lithium bromide absorption unit, the regeneration heat exchanger performs what function on the lithium bromide?
It preheats the weak and cools the strong solution.
What is the purpose of the collection tray on the spot cooler?
To collect condensation from the air around the cooling coils
Dirt should be kept out of a ventilation system for what reason?
Restricts airflow and creates a fire hazard
Which maintenance action is proper for air-conditioning equipment?
After washing, oil the filters with filter oil
Aboard navy ships, compressed air is used for which of the following purposes?
Operating pneumatic tools
Starting Diesel engines
Charging and firing torpedoes
A reciprocating air compressor is generally selected for what capacity requirements?
800 cfm and 5,000 psi
What is the usual source of power for operating air compressors aboard ship?
Steam turbines and electric motors
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?
Flexible coupling
Which of the following is the classification of a medium-pressure air compressor?
Two-stage, vertical, duplex single-acting with a discharge of 151 to 1,000 psi
What cylinder arrangement is used in two-stage, W-type air compressors?
Two cylinders for the first stage and one cylinder for the second stage.
A piston makes what total number of strokes during each operating cycle of a single-acting air compressor?
Two
Which parts are included in the compressing elements of an air compressor?
Air valves, cylinders, and pistons. Unloaders are not part of the compressing elements
The operation of the automatic valves of an air compressor is initiated by what means?
An air pressure differential pressure
What device is used to lubricate the high-pressure air compressor cylinders?
A compressor oil pump
Which of the following means is/are used to cool most high- and medium-pressure air compressors?
Fresh water or sea water
The cylinders and heads of some shipboard air compressors are made from bronze alloy for what reason?
To minimize corrosion
What is the function of the intercoolers of an air compressor?
Remove heat generated during compression and to condense existing vapor
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
False.
What is the purpose of using baffles in tube-type water cooled intercoolers?
To deflect air or water passing through the cooler
The control system for an electrically driven reciprocating air compressor will automatically stop the compressor when the pressure in the receiver causes what action?
The pressure switch to close
The automatic temperature shutdown device of a high-pressure reciprocating air compressor stops the compressor under what condition?
When the cooling water temperature rises above a preset limit
In rotary-type centrifugal compressors, air is compressed by which of the following forces?
Centrifugal force
Which of the following is the purpose of the air receiver in an air compressor?
To minimize pressure variations
What system is supplied by non-vital air?
Laundry equipment
Air hose connection
Tank level indicator systems
What type of compressor supplies air to the prairie-masker system?
A turbo compressor
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?
Venturi effect
What is the cooling medium for oil-free compressor?
Freshwater
What device controls the movement of the A-end of an electro-hydraulic speed gear
A tilt box
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?
The tilt box is placed in a neutral position
When the ram is moving, oil is forced into one ram cylinder and out of the other cylinder to what destination?
Suction side of the main hydraulic pump
Which device maintains hydraulic pressure in the ram-type electro-hydraulic steering gear?
A trick wheel
If the remote steering systems fails, what device is used for local hydraulic control of the steering gear?
A trick wheel
If electrical power is lost to the hydraulic pump motor, what device can be used to control the steering gear?
A hand pump
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 three-way plug, cock-type valve
A windlass has been idle for several months. Before operating the windlass, what maintenance actions should you perform?
Adjust the brake
What type of winch is used to hoist aircraft aboard the ship?
Electro hydraulic
The horizontally mounted drum of an electro-hydraulic winch is connected to the shaft by what device?
A clutch
Electric capstans are usually reversible. Those powered by D.C. Motors usually have what total number of speeds in either direction of rotation?
A
The boom of a crane is controlled by what means?
A
Fouling of the hoisting ropes is prevented by what means?
A
The delicate control often required to handle loads with a crane is usually provided by what means?
A
On a crane, what device is provided to hold the load when electric power fails?
A
What device finds and retains the neutral position of the A-end hydraulic pump on a crane.
A
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
CV class aircraft carriers are equipped with airplane elevators that have what max lifting capacity?
A
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
An electro1hydraulic elevator is raised by high-pressure oil acting directly against what component?
A
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
Power conveyors are configured either vertically or horizontally.
True or false
A
Conveyors are used to handle what kind of supplies?
A
While loading a vertical conveyor, what is the position of the load-unload device?
A
What is the purpose of the interlock switch on a vertical package conveyor?
A
What safety precautions must you take to ensure accident-free operation of horizontal conveyors?
A
The final rinse in a double tank dishwasher is activated by what means?
A
In the double tank dishwashing machine, the final rinse is controlled by an adjustable automatic steam-mixing valve that maintains what temperature ranges?
A
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
