Compresseor Pre-test quiz 2 Flashcards
An overload relief valve must be built into an oil pump to protect the system against excessively high oil pressure
true
A crankcase heater prevents liquid refrigerant from being trapped with the oil in the compressor crankcase
true
A compressor with a splash lubrication system must have greater clearances than a compressor with a pressure lubrication system
false
A screw compressor produces the most vibration of all compressor types
false
In a water cooled compressor, coil water is sprayed onto the motor windings inside the compressor dome
false
on external drive compressors , the crankshaft seal rubbing surfaces should be lubricated
true
All hermetic compressors require a crankshaft seal
false
The vanes on a rotating vane compressor may be brought into contact with the cylinder walls by spring pressure or centrifugal force
true
A _____ compressor compresses vapour between a matched set of helical rotors
screw
An ______ is used to temporarily reduce cylinder pressure during compressor start up
a) splash system
b) gasket
c) muffler
d) unloader
unloader
Which of the following statements regarding mufflers is false?
a) mufflers may be installed on the compressor inlet or outlet or both
b) mufflers reduce noise caused by gas pulsation
c) mufflers are used only in hermetic compressors
c) mufflers are used only on hermetic compressors
Which type of screw compressor is typically used on ammonia or other high pressure systems?
a) open- drive
b) hermetic
c) both a and b
d) neither a or b
open drive
Which of the following methods is not used to modulate the capacity of a scroll compressor?
a) a variable speed motor moves the orbiting scroll at different speeds depending on the load
b) an unloader is used to hold the intake valve open so compression cannot take place
c) a fixed and orbiting scrolls are briefly moved apart opening gaps between the vapour pockets
b)
which of the following explains why exhaust valves present more problems than intake valves?
a) intake valves are continuously lubricated by oil
b) exhaust valves operate at higher temps
c) exhaust valve seats are more likely to collect carbon than intake valve seats
d) all of the above
d) all of the above
In reciprocating compressors, the intake and exhaust valves are located on the_______?
a) cylinder head
b) dome
c) crank case
d) valve plate
valve plate
Reciprocating compressors can be classified by _________
a) cylinder arrangement
b) number of cylinders
c) type of crankshaft
d) all of the above
all of the above
Which of the following best explains why electrical connections and starting relays on hermetic compressors are typically installed outside the comp housing?
a) electrical arcing could break down and contaminate refrigerant leading to a compressor burnout
b) most refrigerants are highly flammable
c) refrigerant is highly corrosive and would damage electrical components
d) all of the above
a)
which of the following statements regarding open drive compressors is false?
a) all open drive compressors have a shaft seal
b) open drive compressors are available in hermetic and semi hermetic models
c) open drive compressors may be belt driven or direct -driven
d) all of the above
b) open drive compressors are available in hermetic and semi-hermetic models
which of the following best describes the action of a dual capacity reciprocating compressor?
a) one piston is attached to a quick release connecting rod, when the crankshaft reversed direction the connecting rod disconnects from the crankshaft disabling the piston
b) one piston has a release valve built into the piston head. when the crankshaft reversed direction the valve opens to prevent compression
c) one piston is on a moveable eccentric. when the crankshaft reversed direction, the eccentric centres on the crankshaft disabling the piston
d) none of the above
c) one piston is on a moveable eccentric
which type of compressor is most similar in construction to an automobile engine?
a) rotary
b) centrifugal
c) reciprocating
d) screw
c) reciprocating
