8-18.
In a refrigerant plant, liquid
refrigerant may flood back to the
compressor from the evaporator if the
thermostatic expansion valve is
1.
stuck shut
2.
adjusted for too high superheat at
the outlet
3.
adjusted for too low superheat at
the outlet
4.
reducing the amount of refrigerant
flowing into the coil
8-19.
If it is suspected that the expansion
valve assembly requires replacement,
which of the following conditions should
be met before an expansion valve test is
made?
1.
The liquid strainers are cleaned
2.
The solenoid valves are operative
3.
The system is sufficiently charged
4.
Each of the above
8-20.
What should a service drum that is used
for testing an expans ion valve contain?
1.
Pressurized R-12
2.
Dry compressed air
3.
A gas similiar to the one used in
the thermal element of the valve
4.
Each of the above gasses
For questions 8-21 through 8-24, assume
that you are testing the thermostatic
expansion valve of a refrigeration plant.
8-21.
When should the thermal element be
immersed in a bath of crushed ice?
1.
Before the valve inlet is attached
to the gas source
2.
After the high and low pressure
gages have been connected
3.
Before the high pressure gage is
connected to the valve outlet
4.
After the valve on the air supply
line has been opened
8-22.
A thermostatic expansion valve is set
for 5°F of superheat, what should the
outlet pressure read on a gage?
8-23.
Which of the following operating
conditions is an indication that the
expansion valve is seating properly?
1.
Low pressure gage stops increasing
after a few pounds
2.
Low pressure gage continues to
increase slowly after a few pounds
3.
Either 1 or 2 above happens
4.
Low pressure gage increases rapidly
and equals the inlet pressure
8-24.
You have removed the ice packing from the
control bulb. Which of the following
outlet pressure conditions indicates that
the valve is operating normally?
1.
The pressure does not change
2.
The pressure decreases rapidly
3.
The pressure increases rapidly
4.
The pressure decreases a few pounds,
then stabilizes
Question 8-25 is to be judged True or
False.
8-25.
The entire expansion valve assembly must
be replaced when the power element is
inoperative.
Learning Objective: Recognize practices
that will help assure a properly
operating refrigeration and air
conditioning system, and identify some of
the symptoms that may lead to system
failure.
8-26.
Under normal operating conditions how
full should the receiver of a properly
charged refrigeration system be when the
compressor stops?
1.
25% full
2.
50% full
3.
85% full
4.
100% full
1.
16.1 psi
2.
22.5 psi
3.
26.1 psi
4.
32.5 psi
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