8-8.
What method should you use to remove
8-13. A refrigeration unit is working under a
foreign deposits from the tubes of a
normal heat load and has a sufficient
refrigerant condenser?
charge of refrigerant. The water side of
the condenser should be cleaned if the
1.
Lance with water only
operating difference between the
2.
Lance with air only
temperature corresponding to the
3.
Both 1 and 2 above
condensing pressure and the temperature
4.
Wash with acid solution
of the outlet circulating water increases
above the temperature obtained when the
8-9.
On an air-cooled condenser, the exterior
unit was in good condition by how many
surfaces of the tubes and fins are dirty
degrees?
and restricting air circulation. What
should be used to clean these surfaces?
1.
5°F to 10°F
2.
10°F to 20°F
1.
Jets of steam
3.
20°F to 30°F
2.
Hot water lances
4.
30°F to 40°F
3.
Compressed air lances
4.
Stiff bristled brushes
8-14. How does the temperature at the outlet
side of the valve compare with the
8-10.
How often should the water side of a
temperature at the inlet side when the
condenser in a freon system be tested for
thermostatic valve is operating properly?
refrigerant leakage?
1.
Daily
2.
Weekly
3.
Bi-weekly
4.
Monthly
8-11.
You are testing condenser tubes for
leakage. Why do you hold the exploring
tube of the leak detector at one end of
each condenser tube for about 10 seconds
before driving a cork into each end of
8-15.
the tube?
1.
To dry the tube heads
2.
To detect the presence of R-12
3.
To draw fresh air through the tube
4.
To vaporize any water left in the
tube
8-12.
You are attempting to locate leaks in a
refrigerator condenser.
For what period
of time should the condenser be allowed
to remain idle after all tubes in the
8-16.
suspected section have been corked,
before continuing the test?
1.
2 to
4 hr
2.
4 to
6 hr
3.
6 to
8 hr
4.
8 to 10 hr
1.
The temperature is lower at the
outlet side
2.
The temperature is lower at the inlet
side
3.
The temperature is approximately the
same at the outlet and the inlet
sides
4.
The temperature is higher at the
inlet side
Which of the following factors can cause
a thermostatic expansion valve to operate
improperly?
1.
A collection of dirt on the
control bulb
2.
A collection of freon at the valve
seat
3.
A collection of dirt at the valve
orifice
4.
Each of the above factors
As a rule, about how many degrees of
superheat are picked up by the
refrigerant vapor before it leaves the
cooling coil?
1.
Between 4°F and 12°F
2.
Between 15°F and 20°F
3.
Between 30°F and 38°F
4.
Between 45°F and 50°F
Question 8-17 is to be judged True or
False.
8-17.
If you increase the spring pressure of
the thermostatic expansion valve to give
a high degree of superheat at the
evaporator coil outlet, you may cause a
low lube oil level in the compressor
crankcase.
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