Compressor Pre-test quiz 1 Flashcards
The function of a compressor is to take refrigerant vapour at a ______ temperature and pressure and change it to a _____ pressure and temperature
low
high
At a constant RPM, a compressor is a _____ displacement device and its capacity is variable depending on the _______ of the refrigerant at the intake of the pump
constant
pressure
A mechanical shaft seal is required in a _________ compressor
open type compressor
All refrigeration compressor valves are opened and closed by ___________
pressure differential
How does a compressor initiate flow in a system?
a) by raising pressure in the evaporator
b) lowering pressure in the evaporator
c) by discharging liquid
d) raising pressure in the condenser
by lowering pressure in the evaporator
by raising pressure in condenser
In this compressor, a piston travels back and forth within a cylinder?
reciprocating
In this compressor two offset spiral disks compress refrigerant vapour
Scroll
This compressor has high speed impeller with many blades. The impeller rotates within a housing
centrifugal
This compressor has a pair of helical rotors. They trap and compresses gases as they revolve in a cylinder.
Screw
What is the fundamental difference between and hermetic and semi-hermetic compressor with regards to mechanical field service?
hermetic is much harder to service due to its metal housing
Most of the heat energy in the suction vapour entering the compressor is:
a) heat of compression
b) sensible heat
c) latent heat
d) defrost heat
sensible heat
List four types of compressors
hermetic
semi hermetic
open drive
belt drive
As suction pressure increases the amount of refrigerant pumped ________ because the specific volume of the refrigerant ________
increases
decreases
List the types of compressor body styles?
hermetic
semi hermetic
open drive
Explain what is meant by saying the compressor rides with the load?
suction pressure goes up, density goes up, capacity goes up, specific volume goes down and volumetric flow rate is constant
List thee ways mechanical cylinder unloading is accomplished?
discharge bypass, suction cutoff, hydraulic
The cylinder unloader method of capacity control is used mainly with?
centrifugal
screw
rotary
none of the above
none of the above
In a scroll compressor;
a) both scrolls move
b) only the upper scroll moves
c) only the lower scroll moves
d) neither scroll moves
only the lower scroll moves
the capacity of a compressor is related to;
a) the speed of the driving motor
b) the compressor displacement
c) number of cylinders
d) all of the above
all of the above
The on/off method of capacity control is normally used with?
a) reciprocating, rotary, and scroll multi-compressor systems
b) rotary compressors
c) scroll compressors
a) reciprocating , rotary, and scroll multi-compressor systems
Excessive foaming in the oil sight glass shows the oil is
a) mixed with refrigerant
b) air
c) acid
d) all of the above
mixed with refrigerant
