Multiple Choice
Identify the
letter of the choice that best completes the statement or answers the question.
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1.
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If an R-12 refrigeration system has its air-cooled condensing unit on a
100°F roof and the condenser outlet temperature (refrigerant) is 115°F, with how much
sub-cooling is the condenser operating?
a. | 30°F | b. | 15°F | c. | 100°F | d. | 130°F |
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2.
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During the defrost cycle of a forced draft low temperature evaporator, the
evaporator fan would ____.
a. | remain on to speed up the defrost | b. | turn off | c. | cycle with the
condenser | d. | cycle with the compressor |
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3.
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A Bourdon tube is often found in a ____.
a. | mercury barometer | b. | aneroid barometer | c. | pressure
gauge | d. | mercury thermometer |
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4.
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Which type of refrigerant has the highest Ozone Depletion Potential
(ODP)?
a. | HFC | b. | HCFC | c. | CFC | d. | All have the same
ODP. |
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5.
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What happens when room temperature water is poured into a glass of ice?
a. | The ice gets colder. | b. | The ice melts because it is giving up the
"cold" to the water | c. | The ice melts because it is absorbing heat from
the water | d. | The ice melts because the water is colder than the
ice. |
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6.
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How many chlorine atoms does it take to destroy 100,000 ozone molecules in the
stratosphere?
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7.
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The temperature of the compressed gas leaving the compressor can best be
described as ____.
a. | cold | b. | cool | c. | warm | d. | very warm |
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8.
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When a refrigerant enters the compressor, it is a ____ and when it leaves the
compressor, it is a ____.
a. | low pressure low temperature superheated vapor, high pressure high temperature
superheated vapor | b. | low pressure low temperature superheated vapor,
low pressure low temperature subcooled vapor | c. | high pressure superheated vapor, low pressure
superheated vapor | d. | low pressure low temperature subcooled liquid,
high pressure high temperature superheated vapor |
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9.
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The compressor in a refrigeration system ____.
a. | raises the boiling point of the refrigerant | b. | pumps the
refrigerant throughout the system | c. | both a and b | d. | none of the
above |
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10.
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An ampere is ____.
a. | the difference in potential between two charges | b. | a measure of the
quantity of electrons flowing past a point in the electrical circuit in a given
time | c. | the unit of measure for resistance | d. | the unit of measure for
capacitance |
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11.
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The best method of leak checking is when the refrigeration system is
____.
a. | in a vacuum | b. | open to the atmosphere | c. | operating with all
fans activated | d. | standing with dry nitrogen pressure of 150 psig in the
system |
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12.
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If two light bulbs are wired in series and one bulb burns out, the other bulb
will ____.
a. | go out | b. | stay on | c. | stay on, but it will
be dimmer | d. | stay on, but it will be brighter |
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13.
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When the load on the evaporator increases, the TX valve ____.
a. | increases the flow of refrigerant | b. | decreases the flow of
refrigerant | c. | maintains constant head pressure | d. | decreases the pressure drop across the
evaporator |
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14.
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A solid material exerts a pressure or force ____.
a. | in all directions | b. | downward only | c. | outward and
downward | d. | outward only |
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15.
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The compressor motor and condenser fan motor are wired in ____.
a. | parallel | b. | series | c. | parallel/series | d. | with minimum wire
length |
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16.
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If the compression ratio of a system with a reciprocating compressor decreases,
the amount of refrigerant pumped by the compressor ____.
a. | will increase | b. | will decrease | c. | will remain the
same | d. | cannot be determined |
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17.
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Which of the following condensers is the most efficient?
a. | forced draft air-cooled | b. | induced draft air-cooled | c. | water-cooled
parallel flow | d. | water-cooled counter flow |
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18.
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The dew-point temperature is the ____.
a. | temperature when the air is saturated with moisture | b. | temperature when the
moisture begins to condense out of the air | c. | difference between the dry-bulb and wet-bulb
temperatures | d. | temperature of the air at 50% relative humidity |
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19.
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The water circuit in shell and coil and coil-type tube-in-a-tube condensers must
be cleaned ____.
a. | by removing the end caps | b. | with a brush | c. | chemically | d. | by air pressure |
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20.
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The generalized comfort chart can be used as a basis to ____.
a. | determine combinations of temperature and humidity to produce comfort in summer and
winter | b. | study air and its properties | c. | determine the amount of fresh air make up
necessary for comfort | d. | none of the
above |
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21.
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Moisture in a liquid state must be ____ before it can be removed with a vacuum
pump.
a. | vaporized | b. | condensed | c. | cooled | d. | solidified |
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22.
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A vapor material exerts a pressure or force ____.
a. | in all directions | b. | downward only | c. | outward and
downward | d. | outward only |
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23.
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When charging a refrigeration system with a near-azeotropic mixture, what must
be done to prevent liquid from entering the system?
a. | Charge only as a vapor through the high side. | b. | Charge only liquid
through the high side. | c. | Charge as a liquid through the low side using a
restrictor. | d. | Charge as a vapor through the low side using a
resistor. |
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24.
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What effect is ozone depletion having on the environment?
a. | increased ground level ozone (smog) | b. | reduced marine life | c. | reduced crop
fields | d. | all of the above |
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25.
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A normally operating water-cooled condenser is operating with a 10°
differential between water in and water out. If the amount of 85°F water going through the
condenser is reduced, which of the following is a possible temperature of the water leaving the
condenser?
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26.
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Of the following choices, the warmest temperature is ____
a. | 20°C | b. | 303°K | c. | 501°R | d. | 77°F |
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27.
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How many Btus must be removed from one pound of water at 200°F for it to
end up as ice at 30°F?
a. | 144 Btu | b. | 828 Btu | c. | 313
Btu | d. | 526 Btu |
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28.
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The Fahrenheit absolute scale is called
a. | Celsius | c. | kelvin | b. | centigrade | d. | Rankine |
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29.
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What is the relative humidity if the dry-bulb temperature is 100 º F and
the wet-bulb temperature is 65°F?
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30.
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The pressure in a refrigeration system is changed in the ____.
a. | condenser and compressor | b. | compressor and expansion
device | c. | expansion device and evaporator | d. | condenser and
evaporator |
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31.
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A helicopter is lifting an 800-pound unit at a rate of 200 feet per minute. How
many horsepower of work energy is the helicopter using in the process?
a. | 3.863 hp | b. | 4.517 hp | c. | 4.848
hp | d. | 5.209 hp |
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32.
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Rotary compressors are used primarily in ____.
a. | large industrial refrigeration and air conditioning systems | b. | residential air
conditioning | c. | small commercial refrigeration units | d. | domestic
refrigerators |
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33.
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A homeowner plans to build a house out in Las Vegas, Nevada, in the middle of
the desert. It would be in his/her best interest to lower the "solar load," to locate most
of the windows on the ____.
a. | north and east sides of the house | b. | east and west sides of the
house | c. | north and south sides of the house | d. | south and west sides of the
house |
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34.
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The ozone depletion factor of R-12 is ____.
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35.
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If 30 oz. of refrigerant are to be added to a refrigeration system and the
supply cylinder weighs 26 lb. 4 oz. before any is added, what will the supply cylinder weigh after
the system has been charged?
a. | 22 lb. 8 oz. | b. | 24 lb. 6 oz. | c. | 24 lb. 8
oz. | d. | 22 lb. 4 oz. |
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36.
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The shell and tube condenser is cleaned ____.
a. | with a brush after removing the end caps | b. | only with
chemicals | c. | with compressed air | d. | with a vacuum
cleaner |
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37.
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A liquid material exerts a pressure or force ____.
a. | in all directions | b. | downward only | c. | outward and
downward | d. | outward only |
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38.
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High efficiency condensers ____.
a. | can withstand higher pressures than standard condensers | b. | have more surface
area than standard condensers | c. | have stainless steel coils | d. | are located in
separate cabinets |
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39.
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PSIA at sea level (under standard conditions) is approximately
a. | 0 PSI | c. | 14.696 PSI | b. | 29.92 PSI | d. | None of the
above |
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40.
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To remove the refrigerant from a system without any testing or processing and to
be put back into the same system is called ____.
a. | recovery | b. | renew | c. | reclaim | d. | recycle |
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41.
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If reservoir-type humidifiers are not properly maintained, which of the
following can be discharged into the air?
a. | fungi | b. | bacteria | c. | algae | d. | all of the
above |
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42.
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The TXV sensing bulb is mounted ____.
a. | on the liquid line between the condenser and the TX valve | b. | at the inlet to the
condenser | c. | on the suction line between the evaporator and the compressor | d. | on the compressor
discharge line |
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43.
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The pressure limiting TX valve ____.
a. | allows the compressor to operate at low condenser entering air
temperatures | b. | shuts off the condenser fan during hot pull down | c. | maintains the full
refrigerant flow rate during a hot pull down | d. | limits the refrigerant flow rate to the
compressor capacity |
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44.
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When a system with a water-cooled condenser cycles off, the water regulating
valve should ____.
a. | remain open during the off cycle | b. | close, since the head pressure is
lower | c. | open all the way to remove any residual heat | d. | re-calibrate itself
to maintain the new lower head pressure |
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45.
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The screw-type compressor is used primarily in ____.
a. | large industrial refrigeration and air-conditioning systems | b. | residential air
conditioning | c. | small commercial refrigeration units | d. | domestic
refrigerators |
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46.
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An extended surface filter (pleated type) ____.
a. | does not clog up as quickly as a standard filter | b. | is able to remove
more dirt since the surface area is larger | c. | costs less than a standard
filter | d. | both a and b |
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47.
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Which of the following can be used to maintain the head pressure of a system
with an air-cooled condenser?
a. | fan cycling | b. | condenser flooding valve | c. | dampers or
louvers | d. | all of the above |
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48.
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If the wet-bulb and dry-bulb temperature are both 80°F, what is the
humidity?
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49.
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A ton of refrigeration is equal to ____.
a. | 1 ton of ice | b. | 288000 Btu/24-hr. | c. | 144
Btu/hr. | d. | 12000 Btu/min. |
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50.
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If the dry-bulb temperature is 93°F and the wet-bulb temperature is
60°F, what is the specific volume of the air?
a. | 14.0 ft3/lb | b. | 14.0 lb/ft3 | c. | 10
lb/ft3 | d. | 10
ft3/lb |
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51.
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When charging liquid refrigerant from a single valve supply cylinder, the
cylinder is placed ____.
a. | upside down | b. | right side up | c. | on its
side |
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52.
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The air temperature of the air off an evaporative cooler is ____.
a. | warmer than the entering air | b. | cooler than the entering
air | c. | the same as the entering air | d. | made up of sensible heat
only |
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53.
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In rotary type motor-compressor assemblies, the motor is cooled by ____.
a. | air over the shell of the assembly | b. | discharge gas from the
compressor | c. | suction gas returning to the compressor | d. | liquid refrigerant
by-passed from the liquid line |
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54.
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A multiple evacuation means that ____.
a. | you connect three vacuum pumps simultaneously to a refrigeration system and pull a
vacuum | b. | you pull a vacuum on three different systems at the same time | c. | you pull a vacuum on
a refrigeration system more than once, allowing refrigerant or nitrogen into the system between each
procedure | d. | there must be more than one system operating before a vacuum can be
pulled |
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55.
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At a constant pressure, the volume of a gas varies as to the absolute
temperature and at a constant volume the pressure of the gas varies directly with the absolute
temperature. This is known as ____.
a. | Charles' Law | b. | Tom's Law | c. | Boyle's
Law | d. | Dalton's Law |
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56.
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The wet-bulb temperature ____.
a. | is the same as the wet-bulb depression | b. | is the saturation pressure | c. | takes into account
the moisture content of the air | d. | is always higher than the dry-bulb
temperature |
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57.
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A house is built on property whose soil is rich in uranium. The occupants of the
house may ____.
a. | be exposed to radon gas | b. | be more susceptible to lung
cancer | c. | smell the pungent odor of the radon | d. | both a and b |
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58.
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On a split air conditioning system with a remote condenser, which refrigerant
lines must be field installed?
a. | discharge and suction | b. | liquid and suction | c. | discharge and
liquid | d. | No lines need to be installed. |
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59.
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To find the watts of electrical power in an electrical circuit, you multiply
____.
a. | ohms and amperes | b. | ohms and volts | c. | volts and
amperes | d. | volts, amperes, and ohms |
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60.
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What can be used to maintain the head pressure of a system with a water-cooled
condenser?
a. | fan cycling | b. | dampers or louvers | c. | water regulating
valve | d. | all of the above |
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61.
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A forced draft high temperature evaporator would ____.
a. | have its fins very close together | b. | not need to be defrosted | c. | need a hot gas
defrost | d. | both a and b |
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62.
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Which of the following terminal combinations would show an open circuit if the
internal overload device in a hermetic compressor should open due to excessive heat?
a. | common to start | b. | common to run | c. | start to
run | d. | both a and b |
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63.
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Balanced port TX valves are used to ____.
a. | feed refrigerant at a normal rate with low condenser entering air
temperatures | b. | feed refrigerant at a normal rate with high condenser entering air
temperatures | c. | stop refrigerant flow with high condenser entering air
temperatures | d. | stop refrigerant flow with low condenser entering air
temperatures |
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64.
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A dirty condenser coil can lead to ____.
a. | increased efficiency | b. | reduced efficiency | c. | increased head
pressure | d. | both b and c |
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65.
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Ice melts in icechests or coolers because ____.
a. | Heat flows through the insulated walls. | b. | Heat enters when the
door is opened | c. | Heat enters when warm food is placed in the chest. | d. | All of the
above |
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66.
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If a low temperature evaporator is forming ice, which of the following is a
possible problem?
a. | evaporator fan not running | b. | compressor not running | c. | condenser fan not
running | d. | no problem, ice formation normal |
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67.
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The total pressure of a confined mixture of gases is the sum of the pressures of
each of the gases in the mixture. This is known as ____.
a. | Charles' Law | b. | Tom's Law | c. | Boyle's
Law | d. | Dalton's Law |
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68.
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Which of the following refrigerants is considered an HFC-type of
refrigerant?
a. | R-134a | b. | R-12 | c. | R-22 | d. | R-11 |
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69.
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Technician "A" says that if the air filter on an air-conditioning
system is totally blocked with dirt, the amperage draw of the evaporator fan motor will go down.
Technician "B" says that if you close down one supply register on a duct system, the volume
of air feeding the other locations will increase slightly. Which of the following statements is
correct?
a. | Technician "A" is correct. Technician "B" is
correct. | b. | Technician "A" is correct. Technician "B" is
incorrect. | c. | Technician "A" is incorrect. Technician "B" is
correct. | d. | Technician "A" is incorrect. Technician "B" is
incorrect. |
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70.
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Condensing temperatures in an air-cooled condensing unit can be reduced by
____.
a. | increasing the condensing surface area | b. | increasing the cfm through the
condenser | c. | decreasing the temperature of the air entering the condenser | d. | all of the
above |
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71.
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Under what conditions would a package air-conditioning system need to be
charged?
a. | during initial installation | b. | during compressor
replacement | c. | after the suction line cracked | d. | both b and c |
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72.
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Comfort can be described as the gentle balance between ____.
a. | air cleanliness, air movement, temperature, and humidity | b. | air velocity, air
cleanliness, humidity, and air movement | c. | air speed, air velocity, temperature, and
humidity | d. | acceleration, air cleanliness, filtration, and
humidity |
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73.
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A refrigeration system is operating with a vapor charged thermostatic expansion
valve. The thermal bulb is sensing a suction line temperature that is higher than the temperature
that allows liquid to be present in the bulb. Any additional increases in the evaporator load will
____.
a. | increase the bulb pressure and cause the thermostatic expansion valve to
open | b. | increase the evaporator pressure and cause the thermostatic expansion valve to
close | c. | decrease the spring pressure and cause the thermostatic expansion valve to
open | d. | have no effect on the position of the needle (pin) in the
seat |
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74.
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What are the relative humidity limits recommended for residences?
a. | 20% to 40% | b. | 30% to 50% | c. | 40% to
60% | d. | 50% to 70% |
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75.
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The heat required for off-cycle defrost is obtained from ____.
a. | supplemental electric heat when the system is shut down | b. | hot gas when the
system is operating | c. | the space temperature when the compressor is
off | d. | hot liquid from the compressor |
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76.
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The human body gives off heat by which of the following?
a. | convection | b. | radiation | c. | conduction | d. | all of the
above |
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77.
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A typical evaporator operating temperature in an air-conditioning system is
____.
a. | 40°F | b. | 55°F | c. | 75°F | d. | 200°F |
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78.
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In reciprocating and scroll type motor-compressor assemblies, the motor is
cooled by ____.
a. | air over the shell of the assembly | b. | discharge gas from the
compressor | c. | suction gas returning to the compressor | d. | liquid refrigerant
by-passed from the liquid line |
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79.
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A compound gauge ____.
a. | indicates pressures above 14.696 psia | b. | indicates pressures in inches Hg below
atmospheric pressure | c. | is one of two gauges on a typical gauge
manifold | d. | all of the above |
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80.
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The factory charge in a split system, using R-22, shows 6 lb. 8 oz. in the
outdoor condensing unit and 2 oz. in the evaporator. The 3/8" liquid line contains 0.48 oz. per
foot and the 7/8" suction line contains 0.10 oz. per foot. The refrigerant lines are 30'
long. What is the correct refrigerant charge for this system?
a. | 6 lb. 10 oz. | b. | 6 lb. 15 oz. | c. | 7 lb. 7
oz. | d. | 7 lb. 11 oz. |
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81.
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Which of the following would allow a system to operate more efficiently?
a. | condenser that had refrigerant leaving with 10° of
subcooling | b. | condenser that had refrigerant leaving with 15° of
subcooling | c. | condenser that had refrigerant leaving as 100% vapor | d. | condenser that had
refrigerant leaving with 10°F of superheat |
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82.
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Control of the head pressure in an air-cooled condenser is done by ____.
a. | cycling the condenser fan | b. | controlling dampers in the airstream through
the condenser | c. | flooding the condenser with refrigerant | d. | all of the
above |
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83.
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The primary function of an expansion device is to ____.
a. | produce a reduction in the pressure on the liquid refrigerant | b. | regulate the flow of
refrigerant into the evaporator | c. | lower the boiling point of the refrigerant far
enough below the temperature of the load to get the needed heat transfer rate | d. | all of the
above |
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84.
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High temperature refrigeration is that produced by ____.
a. | heat from a furnace | b. | an air-conditioning system | c. | the vegetable
cooling system of a refrigerator | d. | the freezer section of a
refrigerator |
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85.
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The reason for using a reducing extended plenum system is to ____,
a. | save metal by using a smaller duct | b. | reduce the operating cost of the
system | c. | provide easier means of fastening the take off fittings | d. | maintain a more even
pressure throughout the entire length of the trunk duct |
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86.
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Which of the following is an example of an HCFC refrigerant?
a. | R-12 | b. | R-402 | c. | R-22 | d. | R-134a |
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87.
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A normally operating water-cooled condenser is operating with a 10°
differential between water in and water out. If scale forms on the water tubes and the entering water
is 85°F, which of the following is possible?
a. | The outlet water will be 88°F. | b. | The system head pressure will
rise. | c. | The water regulating valve will close. | d. | Both a and b are
correct. |
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88.
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One watt of electrical energy is equal to ____.
a. | 3.1416 Btu | b. | 3.413 Btu | c. | 3.3416
Btu | d. | 3.3146 Btu |
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89.
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The condenser in a refrigeration system ____.
a. | desuperheats the vapor from the compressor | b. | condenses the vapor
from the compressor | c. | subcools the liquid refrigerant before it
leaves the condenser | d. | all of the
above |
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90.
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As loads are added in a parallel circuit, the total resistance of the circuit
____.
a. | will increase | b. | will decrease | c. | will remain the
same | d. | cannot be determined |
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91.
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A micron gauge is used to measure ____.
a. | atmospheric pressures at high altitudes | b. | atmospheric
pressures at sea level | c. | absolute pressures below 1 mm
Hg | d. | high pressure in a refrigeration system |
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92.
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If a thermostatic expansion valve's thermal bulb came loose from the
suction line at the outlet of the evaporator, which of the following could result?
a. | The bulb pressure would increase and the thermostatic expansion valve would
open. | b. | The superheat in the evaporator would decrease. | c. | Liquid refrigerant
would flow back to the compressor. | d. | All of the above are
correct. |
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93.
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The controller for a humidifier, a humidistat, has a power element that is ____
sensitive.
a. | moisture | b. | light | c. | infrared | d. | temperature |
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94.
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To reprocess refrigerant to meet new product specifications is called
____.
a. | recovery | b. | renew | c. | reclaim | d. | recycle |
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95.
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Standard atmospheric pressure at sea level is ____.
a. | 29.60" Hg | b. | 29.71" Hg | c. | 29.83"
Hg | d. | 29.92" Hg |
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96.
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If five electrons combine with three protons, the net charge will be
____.
a. | negative | b. | positive | c. | zero | d. | neutral |
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97.
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If the temperature remains constant and the volume that a gas occupies
increases, the pressure will ____.
a. | decrease | b. | increase | c. | remain the
same | d. | cannot be determined from the information given |
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98.
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The purpose of an externally equalized thermostatic expansion valve is to
____.
a. | compensate for excessive evaporator pressure drop | b. | allow system to
equalize faster | c. | prevent the expansion valve from frosting up | d. | allow refrigerant to
expand in the compressor |
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99.
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When exposed to salt air, the material combination used in air conditioning
evaporators and condensers may be ____.
a. | copper tube-stainless steel fin | b. | copper tube-copper fin | c. | copper tube-aluminum
fin | d. | aluminum tube-aluminum fin |
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100.
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If a high temperature evaporator is forming ice, which of the following is a
possible problem?
a. | evaporator fan not running | b. | compressor not running | c. | condenser fan not
running | d. | no problem, ice formation normal |
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101.
|
The two (2) most common substances used in liquid column thermometers are
a. | water & oil | c. | oil & mercury | b. | mercury & alcohol | d. | alcohol &
oil |
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102.
|
The heat in a vapor above its saturation point for that pressure is
called
a. | sensible | c. | specific | b. | latent | d. | superheat |
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103.
|
The dry-bulb temperature is the ____.
a. | same as the wet-bulb temperature | b. | total of the sensible and latent
heat | c. | sensible heat level of the air | d. | sensible heat less the
humidity |
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104.
|
The fitting at the end of a round duct that connects the duct to the floor
register is called a(n) ____.
a. | end boot | b. | reducer | c. | take
off | d. | stack head |
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105.
|
To clean refrigerant by the use of filter dryers is called ____.
a. | recovery | b. | renew | c. | reclaim | d. | recycle |
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106.
|
The discus valve design is more efficient than a flapper valve design because
____.
a. | it allows a compressor design with less clearance volume | b. | it operates with
less spring tension | c. | the amount of expanded vapor in the cylinder is
greater | d. | it will not allow liquid refrigerant in the cylinder |
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107.
|
The refrigerant in a condenser in a refrigeration system ____.
a. | absorbs heat | b. | gives up heat | c. | changes to a
vapor | d. | is under lower pressure than the evaporator |
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108.
|
If a conductor carrying electrical current is formed into a coil, the magnetic
field around the wire will ____.
a. | cancel out | b. | increase | c. | decrease | d. | remain the same |
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109.
|
What happens to the current in a circuit if the resistance is increased?
a. | The current remains the same. | b. | The current increases. | c. | The current
decreases. |
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110.
|
The Celsius absolute scale is called
a. | Fahrenheit | c. | kelvin | b. | centigrade | d. | Rankine |
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111.
|
Which of the following refrigerants has the lowest boiling temperatures at
atmospheric pressure?
a. | R-12 | b. | R-22 | c. | R-134a | d. | R-502 |
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112.
|
More than one evaporator coil circuit is used when ____.
a. | the evaporator is located outside the conditioned area | b. | there would be
excessive refrigerant pressure drop in the coil circuit | c. | a distributor would
not be practical | d. | a slant coil is at an angle more than 60° |
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113.
|
If the suction valve in a reciprocating compressor is leaking slightly, the
____.
a. | cooling capacity will be reduced | b. | flow rate of refrigerant through the system
will increase | c. | compressor can overheat | d. | both a and c |
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114.
|
Most of the heat energy in the suction vapor entering the compressor is
____.
a. | heat of compression | b. | sensible heat | c. | latent
heat | d. | defrost heat |
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115.
|
What is the recommended maximum number of grains per pound of material in the
water supplied to an atomizing humidifier?
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116.
|
A refrigeration system designed for the storage of flowers or candy is
considered a ____ type.
a. | high temperature | b. | medium temperature | c. | low
temperature | d. | sharp freezing |
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117.
|
Which of the following is typically measured with an inclined water
manometer?
a. | static pressure in a duct system | b. | pressure in a refrigeration
system | c. | manifold pressure in a gas fired furnace | d. | nozzle pressure of
an oil burner |
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118.
|
Atomizing humidifiers discharge ____ into the air.
a. | CO2 | b. | electronic ions | c. | tri-valant
oxygen | d. | tiny water droplets |
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119.
|
Refrigerant in vapor form is normally put into the system through the
____.
a. | liquid line | b. | suction line | c. | hot gas
line | d. | liquid return line |
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120.
|
If a low temperature evaporator is forming excess ice, which of the following
could be a possible problem?
a. | The evaporator fan motor is defective. | b. | The unit is not staying in defrost long
enough. | c. | The defrost heater is defective. | d. | All of the above are
correct. |
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121.
|
What is the dew-point temperature if the wet-bulb temperature is 65°F and
the dry-bulb temperature is 100°F?
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122.
|
The purpose of a capillary tube is to ____.
a. | regulate the refrigerant flow into the evaporator | b. | lower the pressure
of the liquid refrigerant | c. | lower the boiling point of the
refrigerant | d. | all of the above |
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123.
|
If an evaporator has a pressure drop of 10 psig and the low side pressure is 15
psig, what is the pressure at the inlet of the evaporator?
a. | 10 psig | b. | 25 psig | c. | 15
psig | d. | 5 psig |
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124.
|
What is the most accurate instrument for checking a deep vacuum?
a. | compound gauge | b. | mercury "U" tube
manometer | c. | mercury barometer | d. | electronic vacuum
gauge |
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125.
|
To insure accurate testing, the best material to use for connecting lines to the
vacuum pump and gauge set is ____.
a. | light flexible hose | b. | heavy duty rubber gauge
line | c. | copper tube | d. | garden hose |
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126.
|
Temperature is an indication of the ____.
a. | amount of heat in a material | b. | density of the material | c. | amount of molecular
activity in the material | d. | weight of the total mass of the
material |
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127.
|
Which of the following represents a different temperature than the other
three?
a. | 15°C | b. | 59°F | c. | 475°K | d. | 519°R |
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128.
|
How many Btus are required to change one pound of ice at 20°F to steam at
220°F?
a. | 1,304 Btu/h | b. | 2,608 Btu/h | c. | 6,520
Btu/h | d. | 3,912 Btu/h |
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129.
|
If the thermal bulb assembly develops a leak, what will occur?
a. | All of the system's refrigerant will leak out. | b. | The bulb pressure
will reduce and the valve will close. | c. | The valve will open to allow more refrigerant
to flow. | d. | It will have no effect on system operation. |
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130.
|
Heat that changes the state of a substance is called
a. | calorie | c. | sensible | b. | BTU | d. | latent |
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131.
|
Electronic air cleaners generally have ____.
a. | ionizing sections | b. | charcoal filters | c. | pre-filters | d. | all of the
above |
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132.
|
Refrigerants that are made up of two refrigerants that, when blended in the
right proportions, combine to make a third stable refrigerant, are called ____.
a. | blends | b. | azeotropes | c. | near
azeotropes | d. | mixtures |
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133.
|
The wet-bulb depression is ____.
a. | the difference between the dry-bulb and wet-bulb temperatures | b. | the same as the
wet-bulb temperatures | c. | the same as the dry-bulb
temperatures | d. | when the air is saturated with moisture |
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134.
|
The cross liquid charge bulb at the TXV contains fluid that ____.
a. | has similar characteristics to the system fluid to prevent liquid refrigerant from
entering the suction line | b. | has different characteristics from the system
fluid | c. | causes the valve to stay open during the off cycle | d. | follows the typical
pressure-temperature relationship |
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135.
|
Mineral deposits in the water portion of a water-cooled condenser act as
____.
a. | a conductor of heat | b. | an insulator | c. | a cleaning
solution | d. | They have no effect on the operation of the
condenser. |
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136.
|
If the resistance against a propeller fan is doubled, the cfm output decreases,
but the amperage draw of the motor ____.
a. | decreases | b. | increases | c. | stays the
same | d. | overheats the motor |
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137.
|
At standard conditions on the Celsius scale, water will boil at ____.
a. | 100°C | b. | 212°C | c. | 32°C | d. | 0°C |
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138.
|
How many Btu's are required to change five pounds of ice at 20°F to
steam at 220°F?
a. | 1,304 Btu/h | b. | 2,608 Btu/h | c. | 6,520
Btu/h | d. | 3,912 Btu/h |
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139.
|
An air-cooled condenser that is operating in a climate that has four distinct
seasons must ____.
a. | have some type of head pressure control | b. | use a water
regulating valve | c. | have a multi-circuit evaporator | d. | operate with zero degrees of
subcooling |
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140.
|
Noncondensable gases ____.
a. | are desirable in a refrigeration system | b. | are undesirable in a
refrigeration system | c. | condense readily under normal atmospheric
conditions | d. | help in pulling a vacuum |
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141.
|
One of the most common substances that is used as an absorber is ____.
a. | charcoal | b. | silica gel | c. | fiberglass | d. | foam rubber |
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142.
|
PSIG indicates ____.
a. | pounds per square inch absolute gravity | b. | pounds per square
inch gage | c. | pounds per square inch of pressure absolute | d. | pounds per square
inch of gravity |
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143.
|
The steps to aggressively controlling the contamination of indoor air would
involve ____.
a. | locating and eliminating the source of contamination | b. | providing adequate
ventilation | c. | providing methods for cleaning the air | d. | all of the
above |
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144.
|
The temperature on the Celsius scale where all molecular activity stops is
approximately ____.
a. | -273°C | b. | -272.6°C | c. | -277.8°F | d. | -274.1°C |
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145.
|
The density of air is the ____.
a. | amount of moisture in the air | b. | amount of movement in the air per cubic
foot | c. | weight of the air per cubic foot | d. | combination of the temperature and pressure of
the air |
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146.
|
To pull a vacuum means to ____.
a. | raise the pressure in a refrigeration system | b. | lower the pressure
in a refrigeration system below atmospheric | c. | allow refrigerant to escape into the
atmosphere | d. | condense the gas in the system |
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147.
|
The capacity of an evaporator is affected by ____.
a. | the saturation pressure of the low side of the system | b. | the saturation
pressure of the high side of the system | c. | the amount of evaporator
superheat | d. | all of the above |
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148.
|
Liquid entering the compression chamber of a reciprocating compressor can lead
to ____.
a. | damaged valves | b. | damaged piston rings | c. | damaged expansion
valves | d. | both a and b |
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149.
|
Measuring velocity pressure in a duct indicates the ____.
a. | volume of air through a duct | b. | speed at which the air is
moving | c. | pressure against the sides of the duct | d. | weight of the air moving through the
duct |
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150.
|
The unit used to measure electrical power is the ____.
a. | volt | b. | ampere | c. | watt | d. | ohm |
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