Power engineering 3B2 Chapter 9 Questions With Complete
Solutions
_____ can be started by use of a compressed air starting motor
or applied high pressure air directly to starting cylinders.
a. Gas turbine engines
b. Steam turbine engines
c. Large diesel engines
d. Gasoline engines
e. Centrifugal pumps. Correct Answers c
_____ compression is preferable because of the lesser amount of
power required to carry out the compression.
a. Adiabatic.
b. Positive displacement.
c. Dynamic.
d. Unloaded.
e. Isothermal. Correct Answers e
_____ compressors are more efficient than other positive
displacement types.
a. Rotary screw.
b. Sliding vane.
c. Rotary lobe.
d. Axial flow.
e. Reciprocating. Correct Answers e
_____ on centrifugal air compressors are provided in order to
control the amount of air flowing to the impeller and thus
control the capacity of the unit.
a. Adjustable inlet vanes
,b. Adjustable diffuser vanes
c. Variable frequency drive
d. Moving and fixed blades
e. Dummy piston. Correct Answers a
A _____ is used to activate the inlet air unloader by monitoring
receiver pressure.
a. Solenoid valve.
b. Spring loaded pilot valve.
c. Spring.
d. Lever.
e. Camshaft. Correct Answers b
A compressor driven by a constant speed driver has its output
varied by:
a. A stop and start switch
b. A solenoid valve
c. A mercury switch
d. Some type of unloading device
e. A safety relief valve. Correct Answers d
A compressor with _____ is known as an angle compressor.
a. A "V" type cylinder arrangement
b. A "Y" type cylinder arrangement
c. One cylinder on the horizontal axis and the other on the
vertical axis
d. Horizontal cylinder arrangement
e. 45o type cylinder arrangement. Correct Answers c
A disadvantage of an electrical hand tool over an air powered
hand tool is:
, a. It is constant speed
b. After prolonged use it becomes magnetized
c. There is a chance of electric shock
d. An electric hand tool cannot be reversed
e. A source of power is more readily available. Correct Answers
c
A fusible plug is required on the air receiver shell to:
a. Remove unwanted moisture and oil.
b. Vent air if the discharge temperature of the air compressor is
too high.
c. Vent the air from the receiver in the event of a fire occurring
in the vicinity of the air receiver.
d. Vent off air if the receiver pressure is up.
e. Release the air pressure should ice be formed. Correct
Answers c
A good method of drying air before it goes into the receiver is
to:
a. Heat it
b. Pressurize it
c. Cool it
d. Increase its velocity
e. Decrease its velocity. Correct Answers c
A method of unloading a reciprocating compressor is to:
a. Hold the discharge valve closed
b. Hold the discharge valve open
c. Place a check valve in the discharge line
d. Hold the inlet valves in the open position
e. Unloading a cylinder. Correct Answers d
Solutions
_____ can be started by use of a compressed air starting motor
or applied high pressure air directly to starting cylinders.
a. Gas turbine engines
b. Steam turbine engines
c. Large diesel engines
d. Gasoline engines
e. Centrifugal pumps. Correct Answers c
_____ compression is preferable because of the lesser amount of
power required to carry out the compression.
a. Adiabatic.
b. Positive displacement.
c. Dynamic.
d. Unloaded.
e. Isothermal. Correct Answers e
_____ compressors are more efficient than other positive
displacement types.
a. Rotary screw.
b. Sliding vane.
c. Rotary lobe.
d. Axial flow.
e. Reciprocating. Correct Answers e
_____ on centrifugal air compressors are provided in order to
control the amount of air flowing to the impeller and thus
control the capacity of the unit.
a. Adjustable inlet vanes
,b. Adjustable diffuser vanes
c. Variable frequency drive
d. Moving and fixed blades
e. Dummy piston. Correct Answers a
A _____ is used to activate the inlet air unloader by monitoring
receiver pressure.
a. Solenoid valve.
b. Spring loaded pilot valve.
c. Spring.
d. Lever.
e. Camshaft. Correct Answers b
A compressor driven by a constant speed driver has its output
varied by:
a. A stop and start switch
b. A solenoid valve
c. A mercury switch
d. Some type of unloading device
e. A safety relief valve. Correct Answers d
A compressor with _____ is known as an angle compressor.
a. A "V" type cylinder arrangement
b. A "Y" type cylinder arrangement
c. One cylinder on the horizontal axis and the other on the
vertical axis
d. Horizontal cylinder arrangement
e. 45o type cylinder arrangement. Correct Answers c
A disadvantage of an electrical hand tool over an air powered
hand tool is:
, a. It is constant speed
b. After prolonged use it becomes magnetized
c. There is a chance of electric shock
d. An electric hand tool cannot be reversed
e. A source of power is more readily available. Correct Answers
c
A fusible plug is required on the air receiver shell to:
a. Remove unwanted moisture and oil.
b. Vent air if the discharge temperature of the air compressor is
too high.
c. Vent the air from the receiver in the event of a fire occurring
in the vicinity of the air receiver.
d. Vent off air if the receiver pressure is up.
e. Release the air pressure should ice be formed. Correct
Answers c
A good method of drying air before it goes into the receiver is
to:
a. Heat it
b. Pressurize it
c. Cool it
d. Increase its velocity
e. Decrease its velocity. Correct Answers c
A method of unloading a reciprocating compressor is to:
a. Hold the discharge valve closed
b. Hold the discharge valve open
c. Place a check valve in the discharge line
d. Hold the inlet valves in the open position
e. Unloading a cylinder. Correct Answers d
