WorksheetsME 433 - Q1E - P2
Total questions: 100
Worksheet time: 50mins
Name
Class
Date
1.
What is the chemical formula of butane?
a)
C<sub>2</sub>H<sub>5</sub>CI
b)
C<sub>3</sub>H<sub>8</sub>
c)
C<sub>2</sub>H<sub>4</sub>O<sub>2</sub>
d)
C<sub>4</sub>H<sub>10</sub>
2.
Type of refrigerant control which maintains pressure difference between high side and low side pressure in refrigerating mechanism.
a)
Suction valve
b)
Expansion valve
c)
Service valve
d)
Solenoid valve
3.
The dividing point between the high pressure and low pressure sides of the refrigerant cycle occurs at the:
a)
expansion valve
b)
compressor
c)
condenser
d)
cooling coil
4.
Boiling temperature of Freon 12 is:
a)
-33.33°C
b)
-78.5°C
c)
-29.8°C
d)
-40.7°C
5.
Boiling temperature of Freon 22 is:
a)
-33.33°C
b)
-29.8°C
c)
-78.5°C
d)
-41.04°C
6.
The way to remove frost from a direct –expansion finned – tube evaporator is to:
a)
send hot gas through the coil
b)
scrape off frost
c)
wash with warm water
d)
shut down warm let frost melt
7.
You want to change refrigerants in a Freon -12 plant using a reciprocating single – acting compressor, Which refrigerant requires the smallest amount of change to the system?
a)
Carbon dioxide
b)
Ammonia
c)
Methyl chloride
d)
Aqua ammonia
8.
Soft copper tubing that is used for refrigerant piping, erected on premises containing other that Group 1 refrigerant must be protected by _____.
a)
supporting it by approved clamps
b)
limiting its length between supports up to 10 feet
c)
a rigid or flexible metal enclosure
d)
wrapping it with insulation tape throughout its length
9.
A Freon-12 refrigeration system is fitted with thermal expansion valves. The valves are rated in:
a)
pound per minute
b)
superheat setting
c)
tons of refrigeration
d)
cubic feet per minute
10.
The vapor cycle in thermal efficiency as the refrigeration cycle is to the _____.
a)
energy efficiency ratio
b)
COP for a refrigerator
c)
COP for a heat pump
d)
Carnot efficiency
11.
Which of the following is the cause if the outlet of a thermostatic valve is warmer than the inlet side?
a)
valve is working properly
b)
valve is not working properly
c)
solenoid valve is not working properly
d)
none of these
12.
How is a thermostatic valve tested?
a)
immersing its bulb in warm water
b)
immersing its bulb in ice water
c)
holding its bulb in one’s hand
d)
shorting out the cutout switch
13.
Which of the following will cause an automatically controlled F-12 compressor to start?
a)
closing of the expansion valve
b)
opening of the expansion valve
c)
closing of the solenoid valve
d)
opening of the solenoid valve
14.
Where is the solenoid coil installed?
a)
horizontally over the valve
b)
vertically over the valve
c)
vertically below the valve
d)
horizontally below the valve
15.
The “refrigerating effect” of a refrigerant is:
a)
A. quantity of heat that 1 pound of refrigerant absorbs while flowing through the evaporator under given conditions
b)
B. amount of heat it can remove in a given time
c)
C. quantity of heat that 1 pound of refrigerant absorbs
d)
A or B
16.
The “refrigerating effect” of a refrigerant is always:
a)
more than its latent heat
b)
more than its sensible heat
c)
less than its sensible heat
d)
less than its latent heat
17.
What will happen if the expansion valve is opened too wide?
a)
A. liquid will flood back to the compressor
b)
B. it will make no difference, as the automatic expansion valve is still operating
c)
C. the condenser coils will overheat
d)
A or C
18.
Which of the following should not be used to clean scale traps?
a)
compressed air
b)
cotton waste
c)
kerosene
d)
diesel oil
19.
If one of the ship’s service boxes suddenly stops cooling, the most likely cause would be the malfunction of the:
a)
discharge valve
b)
King Valve
c)
solenoid valve
d)
expansion valve
20.
Which of the following items is not important when using a halide torch?
a)
move flame slowly around the joints
b)
hold flame close to the joints
c)
adjust to a clear white flame
d)
adjust to a clear blue flame
21.
Which of the following would not cause high head pressure?
a)
Air in system
b)
Overcharge of refrigerant
c)
Circulating water too warm
d)
Liquid freezing back
22.
A “cold diffuser” is a:
a)
Type of condenser
b)
Special valve used as a bypass
c)
Type of evaporator
d)
None of these
23.
Which do you think is the effect of “subcooling”?
a)
It causes flooding back to the compressor
b)
It reduces the horsepower per ton of refrigeration
c)
It increases the compression ratio
d)
It increases the horsepower per ton of refrigeration
24.
Subcooling is to:
a)
Cool the evaporator below its normal temperature
b)
Cool the liquid before it enters the evaporator
c)
Cool a liquid at constant pressure to a temperature lower than its condensing temperature
d)
Cool the refrigerant gas before it enters the receiver
25.
When figuring compression ratio, the ratio will increase with a _____.
a)
A. Lower suction pressure
b)
B. Higher suction pressure
c)
C. Higher discharge pressure
d)
A and C
26.
Copper tubing is used in Freon system because:
a)
it has less internal resistance
b)
it is cheaper
c)
it is easier to check leaks
d)
iron corrodes
27.
The cooling water regulator is actuated by:
a)
an electric relay
b)
pressure of the refrigerant
c)
temperature of the refrigerant
d)
none of these
28.
If there is a 20°F temperature drop between the temperature corresponding to the pressure at the compressor discharge and the condenser outlet, one should:
a)
decrease the amount of circulating water
b)
increase the amount of circulating water
c)
purge the system
d)
none of these
29.
If refrigeration controls were constructed with the little or no differential, the:
a)
compressor would short cycle
b)
icebox would get too cold
c)
icebox would get too warm
d)
refrigerant would be subcooled
30.
What is the use of back pressure regulating valve?
a)
controls the evaporator temperature by throttling the flow of liquid refrigerant
b)
maintains a fixed pressure in the evaporator coils
c)
controls the flow of circulating water in the condenser tubes
d)
controls the temperature in the evaporator coils
31.
Which of the following is the primary purpose of the evaporator?
a)
Transmit latent heat of fusion
b)
Transmit latent heat of evaporation
c)
Absorb latent heat of fusion
d)
Absorb latent heat of evaporation
32.
An automatically controlled Freon-12 compressor will start when the _____.
a)
Expansion valve opens
b)
Solenoid valve opens
c)
Expansion valve closes
d)
Solenoid valve closes
33.
A single trunk piston-type compressor is undesirable for a Freon unit because the:
a)
Lubricant mixes with the refrigerant
b)
Refrigerant reduces the crankcase pressure
c)
Lubricant temperature becomes excessive
d)
Refrigerant becomes superheated
34.
Calcium chloride is sometimes used in refrigeration system as a:
a)
Refrigerant
b)
Lubricant
c)
Primary coolant
d)
Secondary coolant
35.
When the outlet temperature of the evaporator exceeds the inlet temperature the condition is called _____.
a)
Boiling
b)
Superheating
c)
Melting
d)
freezing
36.
Which of the following refrigerants would give the most trouble when operating with warm circulating water?
a)
Freon-12
b)
CO<sub>2</sub>
c)
Ammonia
d)
Ethyl chloride
37.
As Freon leaves the expansion valve:
a)
Pressure increases – volume increases
b)
Pressure decreases –volume increases
c)
Pressure decreases – volume decreases
d)
Pressure increases – volume decreases
38.
The suction pressure switch is actuated by:
a)
Pressure on a bellows
b)
Temperature on a bellows
c)
A thermo-pressure regulator
d)
A thermostatic temperature device
39.
A thermometer senses which of the following?
a)
Latent heat
b)
Sensible heat
c)
Heat of fusion
d)
Specific heat
40.
The capacity of a centrifugal type compressor is controlled by which of the following?
a)
A. Regulating the discharge pressure
b)
B. Regulating the speed
c)
C. Regulating the suction pressure
d)
B or C
41.
Where is solenoid coil installed?
a)
Vertically above the valve
b)
Horizontally above the valve
c)
Vertically below the valve
d)
Horizontally below the valve
42.
What is the condition of the compressor when purging a refrigeration system?
a)
The compressor is running
b)
Compressor is running but the condenser secured
c)
Shut down
d)
Running with the bypass open
43.
What must be done first opening a single packed stop valve?
a)
Loosen the packing before opening
b)
Tighten packing before opening
c)
Check to see that the seal is not scored
d)
None of these
44.
Excessive head pressure is caused by:
a)
A. Flooded condenser tubes
b)
B. Too much cooling water to condenser
c)
C. Cooling water temperature too high
d)
A or C
45.
Everything is in its normal operating position when charging a system except the _____.
a)
Compressor discharge valve
b)
Purge valve
c)
Solenoid valve
d)
King (receiver discharge) valve
46.
How often the condenser must be cleaned?
a)
Once a year
b)
Every month
c)
When pressure goes above normal
d)
Every 6 months
47.
Which do you think is the cause of a hot suction line of a refrigerating compressor?
a)
A. Lack of refrigerant
b)
B. Insufficient condensing cooling water
c)
C. Excess refrigeration
d)
B or C
48.
Which of the following vital components of the refrigeration system where both temperature and pressure are increased?
a)
A. Compressor
b)
B. Condenser
c)
C. Evaporator
d)
A or C
49.
The refrigerant temperature is at its maximum just before it enters the _____.
a)
Expansion valve
b)
Compressor
c)
Condenser
d)
evaporator
50.
The principle of mechanical refrigerant is:
a)
the conversion of a liquid to a gas
b)
the absorption of temperature under heat, pressure, compression and expansion
c)
the compression of a liquid under temperature and expansion
d)
the absorption of heat under temperature, compression pressure and expansion
51.
A thermostat is a:
a)
temperature-operated switch
b)
pressure-operated switch
c)
superheat-operated switch
d)
back-pressure-operated switch
52.
The thermal expansion valve responds to the:
a)
amount of superheat in the vapor
b)
amount of superheat in the liquid
c)
temperature in the evaporator coils
d)
pressure in the evaporator coils
53.
The expansion valve on a Freon system controls the:
a)
superheat of the gas leaving the compressor
b)
back pressure in the evaporator
c)
temperature of the box
d)
superheat of the leaving the evaporator
54.
The purpose of the expansion valve by-pass is to:
a)
increase the efficiency of the plant
b)
increase the capacity of the evaporator
c)
control the refrigerant to the evaporator in case the automatic valves fail
d)
bypass the compressor
55.
The thermal expansion valve:
a)
controls the amount of gas coming from the dehydrator
b)
controls the quantity of liquid refrigerant going to the evaporator coils
c)
controls the amount of gas going to the receiver
d)
removes trapped oil from the refrigerant
56.
The function of the compressor is to:
a)
pull the refrigerant gas through the system
b)
increase the pressure of the refrigerant
c)
discharge the refrigerant to the condenser
d)
all of these
57.
The solenoid valve is controlled by:
a)
the amount of liquid in the system
b)
the amount of gas in the system
c)
the temperature in the condenser
d)
the temperature in the icebox
58.
Oil is added to a Freon compressor by:
a)
shutting down the machine and pouring in through the crankcase inspection plate opening
b)
pumping in with an electric-driven pump
c)
pumping in with a hand pump
d)
pouring through oil hole in base
59.
When adding oil to a Freon system, one must be sure that:
a)
the condenser is shut down
b)
all air is removed from the pump and fitting
c)
there is not too high a suction pressure
d)
the discharge pressure is not too high
60.
If the solenoid valve closed by accident, the compressor would be stopped by which of the following?
a)
automatic trip
b)
low-pressure cutout switch
c)
low-water cutout switch
d)
high-pressure cutout switch
61.
The purpose of the low-pressure cutout switch is to:
a)
cutout the compressor at a set pressure
b)
maintain a preset suction pressure to the compressor
c)
maintain liquid refrigerant at the suction of the compressor
d)
cut compressor in and out at a preset pressure
62.
If the cooling water to the condenser suddenly fails?
a)
an alarm will ring to notify the engineer
b)
the compressor will shut down
c)
the expansion valve will close
d)
the solenoid valve will close
63.
The most likely cause of high superheat would be:
a)
too much refrigerant
b)
expansion valve open too wide
c)
expansion valve closed too much
d)
back-pressure valve set too high
64.
What do you call the liquid researching the compressor through the suction?
a)
superheating
b)
overflowing
c)
flooding back
d)
recycling
65.
The suction pressure switch is operated by which of the following?
a)
electronic current
b)
pressure on a bellows
c)
a relay cutout
d)
thermocouple
66.
If the compressor short-cycles on the high-pressure cutout, which of the following would you check?
a)
a check for too much refrigerant in the system
b)
if plenty of cooling water is running through but it is not picking up heat, the condenser tubes need cleaning
c)
be sure system is getting cooling water
d)
all of these
67.
A Freon unit will tend to short-cycle when operating under:
a)
normal conditions
b)
heavy loads
c)
light loads
d)
all of these
68.
Air is remove from the system by:
a)
opening the purge valve
b)
increasing the amount of cooling water
c)
running the refrigerant through an aerator
d)
running the refrigerant through a deaerator
69.
Short-cycling means that the machine:
a)
runs to slow
b)
stops and starts frequently
c)
runs too fast
d)
grounds out frequently
70.
Thermal expansion valves are usually of the:
a)
A. diaphragm
b)
B. magnetic type
c)
C. bellows type
d)
A and C
71.
When checking zinc plates in a condenser, one should:
a)
install all new plates
b)
clean the plates and renew worn out ones
c)
ground each plate to the shell
d)
paint the plates with red lead
72.
The scale trap is located between the:
a)
compressor and oil separator
b)
expansion valve and evaporators coils
c)
King (liquid) valve and expansion valve
d)
evaporator coils and compressor
73.
When the evaporator coils are located in the icebox, the system is known as:
a)
indirect system
b)
direct system
c)
high-pressure system
d)
low-pressure system
74.
The purge valve is located:
a)
on the receiver discharge
b)
in the highest part of the system
c)
in the lowest part of the system
d)
on the evaporators coils
75.
The solenoid valve is:
a)
a pressure-controlled stop valve
b)
a temperature-controlled stop valve
c)
a Freon-controlled check valve
d)
none of these
76.
The thermal expansion valve is located between the:
a)
solenoid valve and the evaporator coils
b)
charging valve and the solenoid valve
c)
receiver and the king valve
d)
king valve and the solenoid valve
77.
The purpose of the scale trap is to:
a)
dissolved scale and dirt in the system
b)
remove insoluble gases from the refrigerant
c)
remove dirt, scale and metal chips from the refrigerant
d)
control the amount of scale going to the compressor
78.
The oil separator (trap) is located between the:
a)
compressor discharge valve and the condenser
b)
receiver and the expansion valve
c)
receiver and the king valve
d)
condenser and the receiver
79.
The charging connection in a refrigerating system is located:
a)
before the receiver
b)
between the condenser and the receiver
c)
between the receiver and the king valve
d)
between the king valve and the solenoid valve
80.
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)
sheets of litmus paper to all joints and watch for color change
b)
a soapsuds solution, mixed with a little glycerin to hold the solution together, and watch for bubbles
c)
a thin layer of mineral oil to all joints and watch for bubbles
d)
a lighted candle at the joints and watch for leaky spots blowing candle
81.
The relief valve on a CO<sub>2</sub> Machine is located:
a)
next to the king valve
b)
in the compressor head
c)
on the discharge pipe between the compressor and the discharge valve
d)
on the discharge pipe from the condenser
82.
The discharge pressure of the compressor should be:
a)
the pressure which corresponds to a temperature from 5°F below that of the condenser discharge
b)
the pressure which corresponds to a temperature equal to that of the condenser discharge
c)
the pressure which corresponds to a temperature from 5°F to 15°F higher than the condenser discharge
d)
none of these
83.
The purpose of relief valves on refrigeration machines is to:
a)
A. by-pass the compressor when dehydrating
b)
B. prevent overloading in the iceboxes
c)
C. prevent excessive pressure in case of stoppage on the discharge side of the system
d)
A and B
84.
A leaky suction valve can usually be detected by:
a)
a higher suction pressure
b)
a fluctuating suction pressure gauge
c)
closing in on the suction valve having no effect on the suction pressure
d)
any of these
85.
Too low suction pressure could be caused by:
a)
too much oil in the system
b)
shortage of refrigerant gas
c)
dirty scale traps
d)
any of these
86.
What do you call a system in which the evaporator coils are located in a brine solution and the brine is pumped through the inbox?
a)
an indirect system
b)
a double-evaporator system
c)
a direct system
d)
a low-pressure system
87.
Before securing a compressor to do maintenance work on it, be sure to:
a)
A. purge the system
b)
B. have spare parts ready
c)
C. pump down the system
d)
B and C
88.
Obstruction of the valve is usually caused by:
a)
scale
b)
congealed oil the system
c)
water in the system
d)
any of the answer
89.
Excess frost on the evaporator coils:
a)
does not affect the system
b)
takes load off compressor
c)
reduces efficiency of the plant
d)
keeps the icebox cooler
90.
How is a CO<sub>2</sub> system purged?
a)
when is a CO<sub>2</sub> comes out of the purge valve, frost will from on a piece of metal held near the outlet
b)
through the king valve
c)
pumped out with a suction pump
d)
the CO<sub>2</sub> will come of the purge valve in liquid form
91.
If the head pressure is too high:
a)
the relief valve should open and let excess refrigerant pass to receiver
b)
close in on the suction valve
c)
the relief should open before the high-pressure cutout
d)
the high-pressure cutout switch should operate before the relief value opens
92.
The system should be purged:
a)
while starting up
b)
after the system has been shut down for a few hours
c)
while system is operating
d)
once a week
93.
If the compressor had been running satisfactorily for a long period of time but suddenly the compartment temperature started to rise, the trouble must be:
a)
a refrigerant leak has developed
b)
the expansion valve may contain frozen water
c)
the solenoid valve has jammed shut
d)
any of these
94.
If the compressor had been running satisfactorily for a long period of time but the oil level was rising slowly, one should:
a)
check the dehydrator cartridge
b)
check to see if there is too much refrigerant in the system
c)
shut down the compressor and check the oil level with the machine stopped
d)
drain out sufficient oil to bring it down to the proper running level
95.
The purpose of the trap is:
a)
to add oil to the compressor
b)
to remove oil from the refrigerating gas
c)
to remove oil from the charging tank
d)
none of these
96.
Too much oil in the compressor would:
a)
absorb too much refrigerant from the system
b)
deposit oil on the condenser tubes
c)
damage the expansion valve
d)
caused leakage through the shaft seals
97.
The oil level in the compressor should be checked:
a)
just before starting the compressor
b)
after a long period of operation
c)
after an extended lay-up period
d)
while the compressor is in operation
98.
The agent used in an indirect reefer system is:
a)
A. calcium chloride
b)
B. potassium chloride
c)
C. sodium chloride
d)
A or C
99.
Air can be prevented from getting into system by:
a)
running the refrigerant through an aerator
b)
keeping the dehydrator clean at all times
c)
keeping all glands and stuffing boxes on the high-pressure side tight
d)
keeping all glands and stuffing boxes on the
100.
Which of the following would not cause high suction pressure?
a)
suction valve not adjusted properly
b)
expansion valve stuck open
c)
leaky suction valve
d)
insufficient refrigeration
100 %
