Mechanical Engineering Unit 21 To 30 Exam Namemultiple Choice Choose The One Alternative That Best Completes The Statement

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subject Pages 14
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subject Textbook Fundamentals of HVACR 3rd Edition
subject Authors Carter Stanfield, David Skaves
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page-pf1
Exam
Name___________________________________
MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the
question.
1)
1)
What type of detector should be used if a technician is looking for a refrigerant leak in a closed
space?
A)
Electronic sight glass
B)
Fluorescent dye leak detector
C)
Ultrasonic-type leak detector
D)
Electronic leak detector
Answer:
D
A)
B)
C)
D)
2)
2)
The smallest increments displayed on most digital gauges are:
A)
B)
C)
D)
Answer:
D
A)
B)
C)
D)
3)
3)
A tool used for checking system pressures, evacuating systems, recovering systems, and charging
systems is:
A)
A recovery cylinder.
B)
A digital thermometer.
C)
A gauge manifold.
D)
A vacuum pump.
Answer:
C
A)
B)
C)
D)
1
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4)
4)
How does a fluorescent dye leak detector work?
A)
It dyes the refrigerant, so that escaping gas leaves a visible cloud.
B)
It is used in conjunction with ultrasonic detectors to improve the resolution of the
mechanical ultrasound.
C)
It dyes the refrigerant oil so that escaping oil leaves traces of dye.
D)
It is applied evenly to the outside of an area suspected of a leak.
Answer:
C
A)
B)
C)
D)
5)
5)
The operating mechanism inside most refrigeration gauges is:
A)
A diaphragm.
B)
A strain gauge.
C)
A bellows.
D)
A Bourdon tube.
Answer:
D
A)
B)
C)
D)
6)
6)
What specification designates a gauge with an accuracy of 3% for the first third of the scale, 2% for
the middle third, and 3% for the final third of their scale?
A)
B)
C)
D)
Answer:
D
A)
B)
C)
D)
7)
7)
The temperature measurement of the air leaving the air diffusers is called:
A)
Supply-air temperature.
B)
Return-air temperature.
C)
Ambient temperature.
D)
Approach temperature.
Answer:
A
A)
B)
C)
D)
2
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8)
8)
The compound gauge reads:
A)
Pressures above and below atmospheric pressure.
B)
Only pressures below atmospheric pressure.
C)
The pressures on both the low side and the high side of the system.
D)
Only pressures above atmospheric pressure.
Answer:
A
A)
B)
C)
D)
9)
9)
A Bourdon tube is:
A)
A straight twisted tube that untwists with an increase in pressure.
B)
A flattened tube in the shape of a question mark that straightens under pressure.
C)
An evacuated tube that vibrates in the presence of pressure.
D)
A straight, round tube that deforms under pressure.
Answer:
B
A)
B)
C)
D)
10)
10)
What is the maximum reading on a typical R-410a high-pressure gauge?
A)
B)
C)
D)
Answer:
B
A)
B)
C)
D)
11)
11)
What is the maximum reading on a typical R-22 high-pressure gauge?
A)
B)
C)
D)
Answer:
C
A)
B)
C)
D)
3
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12)
12)
The saturation temperature of the refrigerant in the system can be read on the refrigeration
gauges:
A)
On the inside colored scales of the gauge.
B)
By simply taking the pressure reading and dividing it by 1.
C)
By simply taking the pressure reading and dividing it by 3.
D)
By simply taking the pressure reading and dividing it by 2.
Answer:
A
A)
B)
C)
D)
13)
13)
Why can a compound gauge NOT indicate when a system is properly evacuated?
A)
The gas volume in the Bourdon tube will prevent the system from pulling down.
B)
It can only show inches, and there are 25,400 microns in one inch.
C)
The Bourdon tube will suck completely flat.
D)
Compound gauges don't read vacuum.
Answer:
B
A)
B)
C)
D)
14)
14)
When do positive shutoff fittings reduce refrigerant loss?
A)
Only when disconnecting hoses
B)
When fixing broken hoses
C)
When connecting and disconnecting hoses
D)
Only when connecting hoses
Answer:
C
A)
B)
C)
D)
15)
15)
How does an ultrasonic-type leak detector work?
A)
It uses sonar to look for imperfections in the tubing and fittings.
B)
It sees the disturbance in the air surrounding the leak.
C)
It uses Bluetooth wireless technology.
D)
It hears the high-pitched sound of escaping gas.
Answer:
D
A)
B)
C)
D)
4
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16)
16)
What is the maximum reading on a typical R-22 compound gauge?
A)
B)
C)
D)
Answer:
C
A)
B)
C)
D)
17)
17)
To obtain an accurate return-air temperature, what type of thermometer would a technician need
to use to target the return-air grille?
A)
B)
C)
D)
Answer:
C
A)
B)
C)
D)
18)
18)
What color hose connects to the low side of the system, allowing the compound gauge to read the
system low-side pressure?
A)
B)
C)
D)
Answer:
B
A)
B)
C)
D)
19)
19)
What causes the pointer of a dial thermometer to move?
A)
The dial is attracted to magnetic north, but its attraction varies with temperature
B)
A coiled piece of metal with a high rate of thermal expansion
C)
Pressure from the vaporization of a volatile fluid
D)
A set of gears connected to a heat motor
Answer:
B
A)
B)
C)
D)
20)
20)
How many microns are there in an inch?
A)
B)
C)
D)
Answer:
B
A)
B)
C)
D)
5
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21)
21)
Which type of thermometer cannot be used to take air temperature readings?
A)
B)
C)
D)
Answer:
C
A)
B)
C)
D)
22)
22)
Compared to analog thermometers, digital thermometers generally sense temperature changes:
A)
About the same as analog thermometers.
B)
Inversely compared to analog thermometers.
C)
Faster than analog thermometers.
D)
Slower then analog thermometers.
Answer:
C
A)
B)
C)
D)
23)
23)
Why is it dangerous to use gauges only designed for R-22 on a R-410A system?
A)
Because R-410a pressures are backwards from other types of refrigerant
B)
Because R-410a can dissolve the lining of the hoses used on R-22 systems
C)
Because the system pressures can exceed the design limit of the R-22 gauges
D)
Because R-410a and brass form an explosive new chemical compound on contact
Answer:
C
A)
B)
C)
D)
24)
24)
What is the possible error for a gauge that has 1% of full-scale accuracy if the gauge reads up to
300 psig?
A)
Plus or minus 6 psi
B)
Plus or minus 2 psi
C)
Plus or minus 1 psi
D)
Plus or minus 3 psi
Answer:
D
A)
B)
C)
D)
6
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25)
25)
Bourdon tubes work by:
A)
Twisting to the right on a rise in pressure and twisting to the left on a fall in pressure.
B)
Straightening on a rise in pressure and curling on a fall in pressure.
C)
Vibrating at higher frequencies for higher pressures and lower frequencies for lower
pressures.
D)
Curling on a rise in pressure and straightening on a fall in pressure.
Answer:
B
A)
B)
C)
D)
26)
26)
Why is it important to measure the vacuum level on the system?
A)
To determine when evacuation has started
B)
To determine when there is no more air
C)
To determine when there is no more moisture
D)
To determine when evacuation is complete
Answer:
D
A)
B)
C)
D)
27)
27)
What are the two types of thermocouple temperature sensors commonly used in HVACR work?
A)
Type A and type B thermocouples
B)
Type 1 and type 2 thermocouples
C)
Type J and type K thermocouples
D)
Positive and negative temperature coefficient thermocouples
Answer:
C
A)
B)
C)
D)
28)
28)
When the hand wheels on the gauge manifold are turned counterclockwise:
A)
The pressure in the hoses is allowed to travel up to the gauges for a reading.
B)
The pressure in the hoses is shut off from the gauges and no reading can be made.
C)
Refrigerant flow between the outer hoses and the center hose is shut off.
D)
Refrigerant can flow between the outer hoses and the center hose.
Answer:
D
A)
B)
C)
D)
7
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29)
29)
Infrared thermometers measure temperature by:
A)
Sensing the infrared light being emitted by the object.
B)
Sensing the speed of sonar waves leaving the surface of the object.
C)
Detecting the signal of wireless temperature transmitters now incorporated in most modern
air-conditioning systems.
D)
By sensing the amount of ultraviolet light being emitted by the object.
Answer:
A
A)
B)
C)
D)
30)
30)
Which sensor is used to detect temperatures that can be displayed on either analog or digital
instruments?
A)
B)
C)
D)
Answer:
C
A)
B)
C)
D)
31)
31)
If a technician needs to take temperatures in both Fahrenheit and Celsius using a digital
thermometer:
A)
They can switch between Fahrenheit and Celsius on the same thermometer.
B)
They will need a Fahrenheit thermometer and a Celsius thermometer.
C)
They will have to take the reading in Celsius and mathematically convert it to Fahrenheit.
D)
They will have to take the reading in Fahrenheit and mathematically convert it to Celsius.
Answer:
A
A)
B)
C)
D)
32)
32)
What liquids are most often used in a glass-stem thermometer?
A)
Liquid refrigerant or oil
B)
Mercury or alcohol
C)
Special thermometer fluid that is a polymer derivative
D)
Colored water or colored oil
Answer:
B
A)
B)
C)
D)
8
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33)
33)
One advantage of the glass-stem thermometer is that it:
A)
Does not rely on any mechanical or electronic device that can malfunction.
B)
Can easily display the difference between two separate temperatures.
C)
Is more rugged than electronic thermometers.
D)
Can cover a wide range with a precise resolution.
Answer:
A
A)
B)
C)
D)
34)
34)
What type of detector uses ultrasonic waves to detect changes in the density of the fluid traveling
through the pipe?
A)
Electronic leak detector
B)
Electronic sight glass
C)
Ultrasonic-type leak detector
D)
Fluorescent dye leak detector
Answer:
B
A)
B)
C)
D)
35)
35)
The flattened metal tube that moves the dial on a pressure gauge is called a:
A)
Diaphragm gauge.
B)
Bourdon tube.
C)
Bellow.
D)
C gauge.
Answer:
B
A)
B)
C)
D)
36)
36)
The blue gauge and hose on a gauge manifold set are used for:
A)
Reading pressures on the low side of the system.
B)
Connecting to refrigerant cylinders.
C)
Reading pressures on the high side of the system.
D)
Connecting to vacuum pumps.
Answer:
A
A)
B)
C)
D)
9
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37)
37)
How can a thermocouple tip be used to get an accurate line temperature measurement?
A)
Thermocouples cannot be used to measure line temperatures.
B)
The thermocouple wire must be wrapped around the line several times to ensure good
contact.
C)
It must be held firmly against the line and insulated from the surrounding air.
D)
The thermocouple tip must be temporarily soldered to the line.
Answer:
C
A)
B)
C)
D)
38)
38)
What is the purpose of annealing copper tubing?
A)
To prepare the tubing for brazing
B)
To harden the tubing and improve its strength
C)
To remove impurities from the copper
D)
To allow the tubing to be formed without cracking or buckling
Answer:
D
A)
B)
C)
D)
39)
39)
Which of the following will occur if copper is bent?
A)
It will soften.
B)
It will expand.
C)
It will contract.
D)
It will harden.
Answer:
D
A)
B)
C)
D)
40)
40)
Why are pipe threads tapered?
A)
It is simply not practical to make them any other way.
B)
The taper allows room for pipe sealing compound between the threads.
C)
The tapered threads create a smooth inner joint to improve flow.
D)
The taper allows pipe threads to tighten and seal.
Answer:
D
A)
B)
C)
D)
10
page-pfb
41)
41)
What material is used for refrigerant piping heating, air-conditioning, and refrigeration systems?
A)
Aluminum tubing
B)
Iron pipe
C)
Copper tubing
D)
Galvanized pipe
Answer:
C
A)
B)
C)
D)
42)
42)
The outside diameter of schedule 40 black iron pipe is approximately:
A)
The same size as the pipe's nominal size.
B)
¼ inch larger than the pipe's nominal size.
C)
3/16 inch larger than the pipe's nominal size.
D)
1/8 inch larger than the pipe's nominal size.
Answer:
B
A)
B)
C)
D)
43)
43)
When installing a piping system with iron pipe:
A)
The pipe must be cut with a vise.
B)
The pipe must be fitted with a vise.
C)
The pipe must be cut and fitted.
D)
The pipe must be threaded and fitted.
Answer:
C
A)
B)
C)
D)
44)
44)
Hard copper tubing can be joined by:
A)
Flare fittings.
B)
Soldering and brazing.
C)
Brazing, soldering, flaring, or compression.
D)
Compression fittings.
Answer:
B
A)
B)
C)
D)
11
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45)
45)
ACR copper tubing is:
A)
Copper tubing with added metallurgical alloys that resist corrosion from the refrigerant.
B)
Type M, dehydrated copper tubing.
C)
Any type of copper tubing so long as it has been dehydrated.
D)
Type L, dehydrated copper tubing.
Answer:
D
A)
B)
C)
D)
46)
46)
How is HDPE pipe most commonly joined?
A)
B)
C)
D)
Answer:
C
A)
B)
C)
D)
47)
47)
Soft copper tubing can be joined by:
A)
Flare fittings.
B)
Soldering and brazing.
C)
Brazing, soldering, flaring, or compression.
D)
Compression fittings.
Answer:
C
A)
B)
C)
D)
48)
48)
What material is used for natural gas piping?
A)
Copper tubing
B)
Aluminum tubing
C)
Iron pipe
D)
Galvanized pipe
Answer:
C
A)
B)
C)
D)
12
page-pfd
49)
49)
Copper tubing that comes in rigid, straight lengths is called:
A)
ACR copper.
B)
Soft copper.
C)
Tempered copper.
D)
Hard copper.
Answer:
D
A)
B)
C)
D)
50)
50)
The most accurate dimension on tubing is:
A)
The average of the inside and outside diameters.
B)
The outside diameter.
C)
The inside diameter.
D)
The wall thickness.
Answer:
B
A)
B)
C)
D)
51)
51)
What material is most commonly used today for cold-water piping in houses?
A)
Galvanized iron pipe
B)
Copper
C)
CPVC
D)
PVC
Answer:
D
A)
B)
C)
D)
52)
52)
The preferred tool for cutting PVC pipe is:
A)
A hacksaw.
B)
A circular saw.
C)
A pocket knife.
D)
A plastic tubing shear.
Answer:
D
A)
B)
C)
D)
13
page-pfe
53)
53)
Which of the following categories of pipe is black pipe?
A)
Copper pipe
B)
Gold pipe
C)
Aluminum pipe
D)
Iron pipe
Answer:
D
A)
B)
C)
D)
54)
54)
What is the difference between schedule 40 and schedule 80 iron pipe?
A)
They have a different metallurgical composition.
B)
Schedule 40 has a heavier wall than schedule 80.
C)
Schedule 80 has a heavier wall than schedule 40.
D)
Schedule 80 is easier to bend than schedule 40.
Answer:
C
A)
B)
C)
D)
55)
55)
Compression nut, a compression sleeve, and a ferrule comprise which of the following?
A)
Sweat reducing coupling
B)
Sweat ells
C)
Compression joint
D)
Flare joint
Answer:
C
A)
B)
C)
D)
56)
56)
Which phrase best describes the process of heating copper tubing to a temperature of 1,300°F?
A)
B)
C)
D)
Answer:
A
A)
B)
C)
D)
14
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57)
57)
What is the nominal size of pipe or tubing?
A)
The approximate inside diameter
B)
The outside diameter
C)
The exact inside diameter
D)
The wall thickness
Answer:
A
A)
B)
C)
D)
58)
58)
The preferred method of cutting copper tubing for a refrigeration system is with:
A)
A hacksaw.
B)
A circular saw.
C)
A tubing cutter.
D)
A cutting torch.
Answer:
C
A)
B)
C)
D)
59)
59)
What is galvanized iron pipe?
A)
Galvanized iron pipe is simply another name for steel pipe.
B)
Galvanized iron pipe is dipped in zinc to make it resistant to corrosion.
C)
Galvanized iron pipe has an outer Teflon coating to help it resist corrosion.
D)
Galvanized iron pipe has been treated to prevent galvanic corrosion.
Answer:
B
A)
B)
C)
D)
60)
60)
ACR tubing is cleaned, degreased, dehydrated, and sealed to keep its:
A)
Aesthetic appeal.
B)
Nitrogen base high.
C)
Bright shine.
D)
Inside clean.
Answer:
D
A)
B)
C)
D)
15
page-pf10
61)
61)
What material is used for air-conditioning drain lines?
A)
Galvanized iron pipe
B)
CPVC
C)
PVC
D)
Copper
Answer:
C
A)
B)
C)
D)
62)
62)
Galvanized iron, copper, PVC, and CPVC have all been used for:
A)
Small appliances.
B)
Air conditioners.
C)
Large field pipes.
D)
Water piping.
Answer:
D
A)
B)
C)
D)
63)
63)
Which of the following is used for piping natural gas?
A)
Copper
B)
White iron
C)
Black iron
D)
Galvanized iron
Answer:
C
A)
B)
C)
D)
64)
64)
Which size pipe has more threads per inch?
A)
B)
C)
D)
Answer:
A
A)
B)
C)
D)
65)
65)
Types of copper tubing in order of wall thickness from light to heavy are:
A)
B)
C)
D)
Answer:
A
A)
B)
C)
D)
16
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66)
66)
ACR is a type L that has been:
A)
B)
C)
D)
Answer:
B
A)
B)
C)
D)
67)
67)
The steps to connect PVC and CPVC pipe include:
A)
Prime, fit, and then apply solvent.
B)
Fit, clean, prime, and apply the solvent.
C)
Apply the solvent and then fit the pipe.
D)
Clean, prime, apply solvent, and fit the pipe.
Answer:
D
A)
B)
C)
D)
68)
68)
What is the difference between a flare for an R-410A system and a flare for an R-22 system?
A)
Flares for R-410A systems have a larger cone.
B)
Flares for R-410A systems must always be a double flare.
C)
Flares for R-410A systems are formed to 37.5° instead of 45°.
D)
There is no difference.
Answer:
A
A)
B)
C)
D)
69)
69)
To cut out the burr left from the pipe cutter, you must use a:
A)
B)
C)
D)
Answer:
C
A)
B)
C)
D)
17
page-pf12
70)
70)
To allow two pieces of copper tubing to be joined by soldering or brazing without any fitting,
which of the following must be used?
A)
B)
C)
D)
Answer:
B
A)
B)
C)
D)
71)
71)
Galvanized iron pipe has been dipped in molten zinc to make it:
A)
Resistant to heat.
B)
Corrosion resistant.
C)
More aesthetically appealing.
D)
Resistant to water.
Answer:
B
A)
B)
C)
D)
72)
72)
Which of the following statements is TRUE regarding a brazing project on a 3/16 in pipe with a 3
tip, the acetylene and oxygen regulators set at 7 psig, and that begins with heating the pipe first?
A)
The oxygen regulator should be below 6 psig.
B)
The acetylene regulator should be below 6 psig.
C)
The tip size is incorrect for a 3/16 in pipe.
D)
The pipe should not be heated first while brazing.
Answer:
B
A)
B)
C)
D)
73)
73)
Why are acetylene cylinders only used in the upright position?
A)
To take advantage of natural convection
B)
The acetylene cylinders will roll around if they are laid sideways on the floor.
C)
The upright position is more convenient because they take up less space.
D)
To prevent acetone from being pulled out of the cylinder
Answer:
D
A)
B)
C)
D)
18
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74)
74)
What is the purpose of flux?
A)
The flux makes it easier to assemble the fitting.
B)
To prevent the solder from alloying with the pipe
C)
To promote surface tension in the solder
D)
To remove light surface oxidation and prevent new oxidation
Answer:
D
A)
B)
C)
D)
75)
75)
Why are air-acetylene, air MAPP, or air-propane torches preferred over oxyacetylene torches for
soldering copper pipes?
A)
Oxyacetylene torches cannot be used with solder because of the possibility of adverse
chemical reactions.
B)
They all produce a much hotter flame than oxyacetylene torches.
C)
They have smaller, more focused flames than oxyacetylene torches.
D)
Oxyacetylene temperatures can easily overheat the pipe.
Answer:
D
A)
B)
C)
D)
76)
76)
During testing, fluid leaks through a newly brazed joint. What may have occurred to cause this?
A)
The fitting was heated before the pipe.
B)
The pipe was heated before the fitting.
C)
The pipe was cleaned ½ in beyond the fitting.
D)
The pipe was cleaned immediately before brazing.
Answer:
A
A)
B)
C)
D)
19
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77)
77)
Why do acetylene cylinders contain acetone?
A)
Acetone helps keep the cylinder weight balanced by evenly distributing the liquid.
B)
Acetylene gas is dissolved in the acetone liquid.
C)
Acetone chemically reacts with the filler in the tank to produce acetylene gas.
D)
The acetone liquid boils off to form acetylene gas.
Answer:
B
A)
B)
C)
D)
78)
78)
The difference between brazing and soldering is that:
A)
Brazing melts the base metal and soldering does not.
B)
Brazing never requires flux.
C)
Brazing occurs at higher temperatures than soldering.
D)
Soldering occurs at higher temperatures than brazing.
Answer:
C
A)
B)
C)
D)
79)
79)
Which of the following statements concerning nitrogen purging is TRUE?
A)
You should always match the low-side design pressure.
B)
You should always purge between the low- and high-side design pressures.
C)
You should always match the high-side design pressure.
D)
You should always purge below the low-side design pressure.
Answer:
D
A)
B)
C)
D)
80)
80)
Why is it illegal to operate a torch with an acetylene pressure greater than 15 psi?
A)
Acetylene becomes unstable and can explode above 15 psi.
B)
The torch cannot be manufactured to contain pressures exceeding 15 psi.
C)
Hoses cannot be built to handle pressures exceeding 15 psi.
D)
Acetylene is a rare and precious resource that must be used sparingly to ensure a supply in
the future.
Answer:
A
A)
B)
C)
D)
20

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