Exam Questions Flashcards
The slide valve as used with compressors, is used;
A) as a discharge valve
B) for capacity control
C) To prevent liquid return
D) As a suction valve
For capacity control
From the following information determine the net oil pump pressure. Compressor crankcase pressure = 12”hg vac, the pump outlet pressure = 32 psig
12\29 = 0.41 x 14.7 = 6.08 + 32 = 38
It is generally considered good practice to limit the compression ratios for a single reciprocating compressor to a
A) max 20:1
B) max 10:1
C) min 20:1
max 10:1
The clearance volume of a compressor;
A) increases as compression ratio increases
B) increases as compression ratio decreases
C) remains the same as compression ratio decreases
remains the same as compression ratio decreases
One end of the connecting rod is attached to the piston and the other end is attached to the
A) crankshaft counter weight
B) Crankshaft journal
C) Scotch yoke
D) none of the above
crankshaft journal
in a reciprocating compressor the one take and exhaust valves are located on the;
A) cylinder head
B) valve block
C) crank case
D) none of the above
D) none of the above
which of the following statements regarding piston rings is false?
A) A compression ring prevents pressurized refrigerant from blowing past the piston
B) The inner diameter of a piston ring is slightly larger than the piston diameter
C) The ends of piston rings are beveled to allow overlap
D) An oil ring prevents excess oil from entering the cylinder
B) The inner diameter of a piston ring is slightly larger than the piston diameter
A crankshaft that is fast with offset journals is called a;
A) integrated
B) eccentric
C) crank throw type
D) none of the above
C) crank throw type
During off cycle, refrigerant will migrate to the _________ of the system;
A) lowest part
B) Receiver
C) evaporator
D) lowest temperature part
D) lowest temperature part
longer cycles caused by reduced compressor capacity will normally lead to;
A) higher temperature
B) lower temperature
C) higher RH
D) lower RH
d) lower RH
A single, large cylinder and piston could cause vibration and;
A) power surges
B) pressure surges
C) temperature surges
D) capacity surges
B) pressure surges
A reed valve assembly usually consists of a valve plate, an intake valve, an exhaust valve, ___________, and valve retainers
A) valve stops
B) valve backer
C) spring valve
D) valve plate
A) valve stops
Cylinder blocks are normally ____________ to the crankcase
A) screwed
B) bolt
C) taper
D) tight fit
B) bolt
Hermetic compressors are normally run at;
A) a lower speed than open drive ones
B) the same speed as the open drive ones
C) higher speed than open drive ones
D) any speed compare to open drive ones
C) higher speed than open drive ones
In a hermetic compressor, it’s motor is lubricated by;
A) splashed oil
B) oil in refrigerant
C) oil brush
D) open points
B) oil in the refrigerant