問題一覧
1
Which of the following could be used to check a leak in an ammonia system?
Litmus paper and Sulfur Stick
2
Ammonia leaks in the condenser can be detected by:
Applying litmus paper to the circulating discharge
3
A sulfur stick burning in the presence of ammonia will give off a...
dense white smoke
4
An ammonia leak will turn litmus paper...
blue
5
In an ammonia system the oil gauge must be kept.
closed except when checking oil level
6
Valves and piping in an ammonia system are made of:
iron
7
The relief valve on an ammonia machine is located:
on the discharge pipe from the condenser and compressor
8
When purging an ammonia condenser into a bucket of water, one can tell when the air is out and ammonia starts to come through by the:
change of bubbling sound of air to the crackling sound of ammonia
9
The crossover connection in an ammonia system can be used to...
hot-gas defrost
10
How is an ammonia system purged so that operator not be overcome by the fumes?
Into a bucket of water
11
Thermal expansion valves are usually of the:
diaphragm and bellows type
12
When checking zinc plates in a condenser, one should:
clean the plates and renew worn out ones
13
The scale trap is located between the:
king (liquid) valve and expansion valve
14
When the evaporator coils are located in the icebox, the system is known as:
direct system
15
The purge valve is located:
in the highest part of the system
16
The solenoid valve is:
a temperature-controlled stop valve
17
The thermal expansion valve is located between the...
solenoid valve and the evaporator coils
18
The purpose of the scale trap is to:
remove dirt, scale and metal chips from the refrigerant
19
The oil separator (trap) is located between the
compressor discharge valve and the condenser
20
The charging connection in a refrigerating system is located
between the king valve and the solenoid valve
21
The dehydrator is located between the...
receiver and the expansion valve
22
The charging valve is located between the...
king valve and the expansion valve
23
23. The solenoid valve is located between the...
scale trap and the thermal expansion valve
24
A device used to keep moisture from passing through the system is called:
dehydrator
25
The relief valve is located on the...
discharge side of the compressor
26
The dehydrator is used
to remove moisture from the system and adding refrigerant to the system
27
Which of the following is another name for the liquid valve?
king valve
28
If no gaskets are used in the piping joints of a Freon system, the joints must be...
ground joints
29
A device for holding open the suction valve and drawing gas from the suction manifold and returning it to the suction line without compressing it is called...
cylinder unloader
30
The solenoid valve can be typed as a...
magnetic stop valve
31
The compressor discharge becomes frosted, the probable cause would be...
refrigerant flooding back
32
Which of the following is the most appropriate definition of Latent heat?
heat added to change the state of a substance
33
If there were a 15°F to 20 F temperature differential between the temperature corresponding to the pressure at the compressor discharge and the temperature at the condenser outlet, it would probably indicate the need for...
purging the system
34
Which of the following is important for evaporator coils?
it should have air completely surrounding them
35
Which do you think is very important in adjusting compressor "V" belts?
allow about ½" slack
36
What will happen to the capacity if the superheat is increased on the suction side?
decreases
37
The cooling water regulator is automatically actuated by which of the following?
the discharge pressure of the refrigerant
38
What usually happens if the specific gravity of the brine is too low?
the brine will freeze
39
The temperature bulb of the solenoid valve is attached to the...
wall of the icebox
40
How is a one-ton plant described?
remove the heat required to melt one ton of ice in 24 hours
41
What is the use of the suction pressure regulating valve?
maintains the back pressure in the
42
The temperature bulb of the thermo-expansion valve is attached to which of the following?
evaporator coil outlet
43
If there is too much lube oil in the system, what must be done?
remove same at once
44
How do you call the process of changing a solid to a liquid?
fusion
45
A double trunk piston is used to
all of the above
46
Where is the excess refrigerant removed?
charging side of the system
47
Which of the following must be considered when adding or removing oil from a refrigerator unit?
all of the above
48
When removing reusable refrigerant from a system, the line to the storage drum must...
contain a strainer-dryer
49
If the expansion valve capillary tube is pinched, which of the following must be replaced?
all of the above (called the power element unit)
50
The thickness of the head gasket is important because it may cause...
all of the above
51
If a Freon -12 compressor trip out on "cut-out, the solenoid valve closes by which of the following?
an electrical release
52
A compressor capacity reduction device reduces compressor capacity...
as the refrigerant load dictates
53
A bull’s eye in a full liquid line will appear .
clear
54
Which of the following is also known as the “hidden heat” in refrigeration work?
latent heat
55
All refrigerator compressor valves are opened and closed by
springs
56
The bulb for the thermal expansion valve is located
near the evaporator coil outlet
57
The elements of a thermostat switch are usually of the
bimetal type
58
The expansion valve is located between the...
receiver and evaporator
59
The oil separator is located between the...
compressor and condenser
60
Zinc rods are found in the...
salt-water side of condenser
61
A double-trunk piston is used to
all of the above
62
Which of the following gasket materials should be used on a Freon system?
Asbestos and Metallic
63
Many pressure gauges on a Freon system have two dials or graduations on one gauge. The two dials represents...
pressure and temperature
64
A double-pipe condenser has .
a small pipe inside a larger pipe, the cooling water passing through the small pipe and the refrigerant through the large pipe.
65
40. When there is a Freon leak, the halide torch will burn:
green
66
Large leaks in a Freon system cannot always be detected with a halide torch because it changes color with the slightest amount of Freon present. A large leak can be detected easier by applying
A soapsuds solution together, mixed with a little glycerine to hold the solution together, and watch for bubbles.
67
The relief valve on a CO₂ machine is located...
on the discharge pipe between the compressor and the discharge valve
68
The discharge pressure of the compressor should be...
the pressure which corresponds to a temperature from 6°F to 15°F higher than the condenser discharge.
69
The purpose of relief valves on refrigeration machines is to...
prevent excessive pressure in case of stoppage of the discharge side of the system.
70
A leaky suction valve can usually be detected by...
any of the above
71
Too low suction pressure could be caused by...
any of the above
72
What do you call a system in which the evaporator coils are located in a brine solution and the brine is pumped through the icebox?
an indirect system
73
Before securing a compressor to do maintenance work on it, be sure to.
D,B, and C
74
Obstruction of the expansion valve is usually caused by.
any of the above
75
Excess frost on the evaporator coils...
reduces efficiency of the plant