Chapter 27 Flashcards
(30 cards)
A piston rod in a double-acting compressor has:
Select one:
A.
Linear travel at one end only
B.
Angular travel at both ends
C.
Linear travel at both ends
D.
Angular travel at one end only
E.
Linear travel at one end and angular at the other
C.
Linear travel at both ends
A typical two-stage compressor might have an automatic shutdown device, which would operate in the event that any except one of the following conditions occurred:
Select one:
A.
High discharge air temperature
B.
High lubricating oil level
C.
High intercooler temperature
D.
High discharge air pressure
E.
High lubricating oil temperature
E.
High lubricating oil temperature
Generally, dynamic compressors favor:
Select one:
A.
Time
B.
Speed
C.
Pressure
D.
Temperature
E.
Volume
E.
Volume
An example of a dynamic compressor is the _____ compressor.
Select one:
A.
Rotary screw
B.
Sliding vane
C.
Centrifugal
D.
Reciprocating
E.
Rotary lobe
C.
Centrifugal
The rotary screw compressor features two intermeshing rotors contained within a close-fitting casing the:
Select one:
A.
Female rotor has six concave flutes
B.
Female rotor is driven by means of timing gears
C.
Male rotor is usually the driven one
D.
Rotors do not come in contact with each other so internal lubrication is not required.
E.
Male rotor has four concave lobes
E.
Male rotor has four concave lobes
The impellers of a rotary lobe compressor maintain their relative positions with each other by the use of:
Select one:
A.
One impeller is driven by the other
B.
Timing gears; one impeller is driven directly and the other by means of the timing gears
C.
One impeller drives the other by means of the timing gear
D.
Both gears are driven by means of the timing gears
E.
Both gears are driven directly
B.
Timing gears; one impeller is driven directly and the other by means of the timing gears
The sliding vane compressor operates at speeds of up to:
Select one:
A.
4000 r/min
B.
5000 r/min
C.
1000 r/min
D.
2000 r/min
E.
3000 r/min
E.
3000 r/min
An example of a dynamic compressor is the _____ compressor.
Select one:
A.
Rotary screw
B.
Axial flow
C.
Rotary lobe
D.
Reciprocating
E.
Sliding vane
B.
Axial flow
When the adsorbent becomes saturated it is reactivated by taking the bed out of operation and heating it to about _____ driving the adsorbed moisture off by evaporation.
Select one:
A.
100°C (212°F)
B.
50°C (122°F)
C.
250°C (482°F)
D.
150°C (302°F)
E.
200°C (392°F)
D.
150°C (302°F)
An air receiver is a pressure vessel whose specifications must conform to the:
Select one:
A.
ASME Code, Section IV
B.
ASME Code, Section VIII
C.
ASME Code, Section III
D.
ASME Code, Section VI
E.
ASME Code, Section I
B.
ASME Code, Section VIII
A typical two-stage compressor might have an automatic shutdown device, which would operate in the event that any except one of the following conditions occurred:
Select one:
A.
Excessive vibration
B.
Low discharge air temperature
C.
Low lubricating oil pressure
D.
Cylinder lubricator stopped
E.
Low lubricating oil level
B.
Low discharge air temperature
Intercoolers should be provided with all of the following except a:
Select one:
A.
Safety valve
B.
Shut off valve
C.
Thermometer on the compressed air side
D.
Pressure gauge
E.
Thermometer on the cooling water side
B.
Shut off valve
The following are all reasons for cooling the air except:
Select one:
A.
Intercoolers increase the amount of power required to compress the air
B.
If water vapour is not removed from the air, it may collect in pipelines and cause water hammer or damage from freezing.
C.
Cooling the air during compression increases the efficiency of operation so that costs are reduced.
D.
Reducing the air temperature makes cylinder lubrication more effective
E.
To remove water vapour and oil vapour from the air between compression stages and after the last stage.
A.
Intercoolers increase the amount of power required to compress the air
A single-stage centrifugal compressor is one with a single impeller and may be able to compress atmospheric air to a pressure of about:
Select one:
A.
600 kPa (87 psi)
B.
100 kPa (14.5 psi)
C.
300 kPa (43.5 psi)
D.
200 kPa (29 psi)
E.
500 kPa (72.5 psi)
C.
300 kPa (43.5 psi)
The rotary screw compressor is suitable for speeds up to:
Select one:
A.
5000 r/min
B.
8000 r/min
C.
3000 r/min
D.
12 000 r/min
E.
10 000 r/min
D.
12 000 r/min
The rotary lobe compressor runs at speeds up to about:
Select one:
A.
1500 r/min
B.
1000 r/min
C.
1250 r/min
D.
2500 r/min
E.
1750 r/min
E.
1750 r/min
The temperature very exceptional circumstances may be about _____ near the end of the compression stroke.
Select one:
A.
175°C (347°F)
B.
150°C (302°F)
C.
75°C (167°F)
D.
225°C (437°F)
E.
90°C (194°F)
D.
225°C (437°F)
One of the categories of air compressors is the _____ type.
Select one:
A.
Rotary lobe
B.
Reciprocating
C.
Rotary screw
D.
Centrifugal
E.
Dynamic
E.
Dynamic
A disadvantage of the sliding vane compressor is that it:
Select one:
A.
Is less efficient than the reciprocating compressor
B.
Has low starting torque requirements
C.
Has a lower initial cost
D.
Produces a steadier flow of air
E.
Does not require inlet or discharge valves
A.
Is less efficient than the reciprocating compressor
Internal lubrication of the compressor refers to lubrication of all of the following except the:
Select one:
A.
Casings of the applicable compressor
B.
Pistons
C.
Vanes
D.
Cylinder walls
E.
Crankshaft bearings
E.
Crankshaft bearings
Some uses of compressed air in buildings include all of the following except:
Select one:
A.
Mixing or agitating in water treatment processes
B.
Extinguishing fires in buildings.
C.
Operating building environmental control systems
D.
Atomizing fuel oil
E.
Starting engines
B.
Extinguishing fires in buildings.
The crosshead in a double-acting compressor serves as a bearing and is the point where:
Select one:
A.
Circular motion becomes angular motion
B.
Circular motion becomes linear motion
C.
Circular motion stops
D.
All motion stops
E.
Linear motion stops
B.
Circular motion becomes linear motion
One of the most common designs of a rotary compressor is the _____ type.
Select one:
A.
Centrifugal
B.
Rotary lobe
C.
Turbine
D.
Positive displacement
E.
Axial flow
B.
Rotary lobe
In a single-acting type of reciprocating compressor:
Select one:
A.
Compression and discharge take place at both ends of the cylinder
B.
Compression and discharge take place at one end of the cylinder only
C.
Compression takes place after discharge
D.
Compression takes place at one end and discharge at the other
E.
There are two compression strokes per revolution of the crankshaft
B. Compression and discharge take place at one end of the cylinder only
