In order for water at 60�F to boil, it must absorb both sensible and latent heat
True
The temperature on the Fahrenheit scale where all molecular biology activity stops is
-460 F
The amount of heat needed to change the temperature of a substance will vary with the type of substance. This heat quality is called the ____ of the substance.
Specific Heat
Which of the following represents a different temperature than the other three
475 deg K
Temperature can be thought of as
a description of the level of heat
Temperature difference does not affect heat transfer rate.
False
Water boils at 212�C.
False
How many Btus must be removed from one pound of water at 200�F for it to end up as ice at 30�F
313 Btu
As the temperature of a material increases, the molecules in the material
travel faster
The Fahrenheit scale is used in the English measurement system by the United States.
True
When water at 212�F boils, it is only absorbing latent heat
True
The two common temperature scales used by air conditioning and refrigeration technicians are called _ and
F & C
The temperature on the Celsius scale where all molecular activity stops is
-273 Deg C
How many Btus are required to change five pounds of ice at 20�F to steam at 220�F?
6,520 Btu
The standard atmospheric pressure at sea level is
29.92 In hg
The Celsius absolute scale is called the _ scale.
Kelvin
The difference in the level of heat between two substances will determine the heat transfer rate between the substances.
True
A Bourdon tube is often found in a(n)
pressure gauge
Of the following choices, the warmest temperature is
303 deg K
PSIG indicates
pounds per square inch gauge pressure
PSIA at sea level under standard conditions is
14.696psi
The Celsius equivalent of 80�F is
26.7 C
The Fahrenheit absolute scale is called the _ scale
Rankine
Both sensible heat and latent heat transfers can be read with a thermometer.
False
Water at 0�F has no heat energy or molecular activity.
False
The laws of thermodynamics can help us to understand what heat is all about.
true
How many Btus are required to change one pound of ice at 20�F to steam at 220�F?
1,304 Btu
The difference in the volume of two substances will determine the heat transfer rate between the substances.
False
At standard conditions on the Celsius scale, water will boil at
100 C
Pure water boils at a temperature of 212�F at which of the following standard conditions
14.696
If the temperature remains constant and the volume that a gas occupies increases, the pressure will
decrease
A law of conservation of energy states that energy is neither created nor destroyed.
true
As heat is applied to a closed container containing a gas, the pressure inside the container will decrease
False
The law that states that "energy is neither created or destroyed, but can be converted from one form to another" is called the
law of conservation of energy
The unit used to measure electrical power is the
watt
How many watts of electrical power are equal to 1 horsepower
746
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 _
Daltons law
The unit of measurement of electrical power is the
watt
Specific volume is the term used to indicate the space a weight of gas will occupy.
true
One watt of electrical energy is equal to
3,413 Btu/h
The volume of gas varies inversely with the absolute pressure, provided the temperature remains constant. This is called
Boyles law
______ ft-lb of work is accomplished when an 800-lb condensing unit is lifted to the top of a 40-ft building
32,000
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?
4,848 hp
A liquid material exerts a pressure or force
outward & downward
A solid material exerts a pressure or force
downward only
A material that occupies space and has mass is called
matter
An example of a fossil fuel is hydrogen
false
A vapor material exerts a pressure or force
in all directions
Heat is a form of energy because of the motion of molecules
true
Most of the energy we use comes from something we already have on Earth. The only "new" energy we get comes from the
sun
One horsepower of work energy equals the amount of work done when lifting _ pounds to the height of _ foot in _ minute.
33,000, 1, 1
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
charles law
Matter exists in three states: _, _, and _.
solid, liquid, & gas
Good ventilation is important when working around refrigeration equipment because modern refrigerants
are heavier than air and may displace the oxygen around you
What happens when room temperature soda is poured into a glass of ice?
The ice melts because it is absorbing heat from the soda.
The halide leak detector should be used in well ventilated areas as the resulting blue or green flame indicates that phosgene gas is being produced.
true
The evaporator in a refrigeration system
absorbs heat from the product to be cooled
The evaporator in a refrigeration system must be colder than the refrigerated space in order to absorb heat.
true
The condenser
rejects heat from the refrigerant
Which of the following refrigerants has the lowest boiling temperatures at atmospheric pressure?
R-502
The boiling point of a refrigerant should be low enough at atmospheric pressure to keep the system pressure above 0 psig when operating at low temperatures.
true
The compressor in a refrigeration system
pumps refrigerant through the system
Ice melts in iceboxes 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 icebox
Selected: d.
All of the above.
High temperature refrigeration is that produced by
an air-conditioning system
Modern refrigerators have become state-of-the-art appliances and some models even include automatic beverage and ice dispensers, built in television screens and connections to the World Wide Web.
true
Only liquid refrigerant should enter the metering device.
true
The ____ are used to change the vapor to a liquid and the liquid form back into a vapor, the refrigeration cycle.
condenser and evaporator
A ton of refrigeration is equal to
288,000 Btu/24 h
Refrigeration can be described as
the process of removing heat from a place where it is not wanted to a place where it makes little or no difference
The only location where the refrigerant vapor is superheated is in the evaporator.
false
The law requires technicians to recover refrigerant from all refrigeration systems so that they ____.
all of the above.
When a refrigerant enters the compressor, it is a ____ and when it leaves the compressor, it is a ____.
low pressure low temperature superheated vapor, high pressure high temperature superheated vapor
The discharge gas from the compressor is a high pressure, high temperature, superheated vapor.
true
If a cylinder of R-22 is moved from a 100�F truck body into an 80�F shop, the quantity of liquid refrigerant in the cylinder will remain the same.
false
An expansion valve is the pressure reducing device that controls the flow of liquid refrigerant into the evaporator.
true
The ____ relationship correlates the vapor pressure and the boiling point of water and is the basis for controlling the cooling system's temperatures.
temperature/pressure
The evaporator can be thought of as a "heat sponge.
true
The temperature inside the refrigerator fresh food section should be about ____.
35 f
The refrigerant vapor picks up additional heat as it flows from the evaporator to the compressor. The heat is picked up from the _.
suction line
The _ is another positive displacement compressor and is used for larger air conditioning and refrigeration applications.
screw compressor
The amount of heat a refrigerant contains with -40 degree F as the 0 heat content reference point is called _.
enthalpy
1.
Orchid
Selected: d.
R-502
This answer is correct. The correct answer is:
R-502
2.
Light blue
Selected: h.
R-134a
This answer is correct. The correct answer is:
R-134a
3.
Green
Selected: f.
R-22
This answer is correct. The correct answer is:
R-22
4.
Sil
...
1.
80.5 psig
Selected: a.
R-502
This answer is correct. The correct answer is:
R-502
2.
37 psig
Selected: b.
R-12
This answer is correct. The correct answer is:
R-12
3.
68.5 psig
Selected: d.
R-22
This answer is correct. The correct answer is:
R-22
4.
35.
...
1.
Absorbs heat from the system.
Selected: d.
?Condenser
This answer is incorrect. The correct answer is:
?Evaporator
2.
Is the heart of the refrigeration system.
Selected: a.
?Compressor
This answer is correct. The correct answer is:
?Compressor
3.
Rejec
...
Reciprocating compressors have ____.
piston and cylinder
Vapor is more dense than liquid and, as the liquid refrigerant boils, it has a tendency to sink.
false
When it is necessary to perform electrical work in an area that has a damp or wet floor, which of the following can be done to minimize the chance of electrical shock?
All of the above
In electrical circuits, the _____ wire protects the operator.
grounding
Fires that involve ordinary materials such as paper, cardboard, and wood are classified as Type __________ fires.
A
An example of a pressure vessel is ____.
a cylinder containing refrigerant
A double insulated drill ____.
generally has a plastic case with the electrical connections and motor insulated within the tool
A fusible plug is a metal fitting that has a hole drilled through it and the hole is filled with ____.
material with a low melting point
Fire extinguishers that can be used on any type of fire, A, B, or C generally contain a _____ to extinguish the fire.
dry chemical powder
Aluminum ladders are safe to use around electrical equipment as long as they have insulation pads on the bottom of the rungs.
false
A way to move equipment across a roof is to use rollers and _ for a base.
plywood
Fires that involve electrical equipment are classified as Type _____ fires.
C
Power tools that are not double insulated must have three-prong plugs to ensure that the tool is properly _.
grounded
If you are a refrigeration technician, a warm coat and gloves should be in your truck, even in the middle of the summer.
true
To insure proper operation of an oxygen cylinder regulator, make sure no oil residue is present.
true
As long as the torch is kept moving below the level of the liquid refrigerant in the cylinder so as not to create a hotspot, it is OK to heat the cylinder in this manner.
false
A necessary safety practice for a technician is to lockout the panel with a padlock and keep the key with you.
true
When working in a machine room, safety glasses should not be worn because they can fog up and impede your eyesight.
false
Which of the following statements is correct when referring to large refrigerant or nitrogen tanks?
all of the above
It is possible that your hand would suffer frostbite if it comes in contact with liquid R-22 when accidentally releasing refrigerant into the atmosphere (an illegal procedure).
true
When transferring refrigerants from a cylinder to a refrigeration system or any other container, you should always wear ____.
goggles with side shields and gloves
An R-22 cylinder containing enough refrigerant to have liquid refrigerant in it, is in a truck with a temperature of 120�F. What would be the psig pressure in the cylinder?
259.9 psig
Oil must never be used around a(n) _ cylinder.
oxygen
Fires that involve ordinary materials such as oil and gas are classified as Type __________ fires.
B
A cylinder with 1,500 sq. in. of internal surface contains R-22 and is in a service truck body at 120�F. What is the total outward force of the refrigerant against the inner wall of the cylinder in tons of pressure?
194.92
Refrigerants from a refrigeration system that has a burned out motor-compressor assembly can be dangerous because it could contain a high concentration of _.
acid
Electrical power should always be shut off at the _____ or entrance panel and locked out in an approved manner when installing equipment.
distribution
When required to drill holes on a roof that has no power supply, the best drill for the job would be a(n) _.
battery operated cordless drill.
A sling psychrometer ____.
measures the dry-bulb and wet-bulb temperatures of air
Mercury bulb-controlled thermostats require that they are installed perfectly horizontal. The tool used to accomplish this is called a(n) _.
level
Flare nut wrenches are used to ____.
tighten or loosen nuts on copper tubing
1.
Hacksaw
Selected: b.
Plasterboard / fiberboard
This answer is incorrect. The correct answer is:
Metal stock
2.
Tubing cutter
Selected: a.
Soft-drawn copper tubing
This answer is correct. The correct answer is:
Soft-drawn copper tubing
3.
Utility knife
...
Tube cutters are used to ____.
cut copper tubing
A(n) _ is used to measure the percentage of CO in flue products.
carbon monoxide indicator
The halide leak detector ____.
detects refrigerant leaks in a refrigeration system
Evacuating a system is accomplished with a(n) _ and helps to remove air and non-condensable gases from a system.
vacuum pump
The odd shape of the Torx type screw driver is the square shaft used to tighten or loosen set screws.
false
A programmable charging scale measures the volume of refrigerant flow into a refrigeration system.
false
A gauge manifold used in refrigeration work may include ____.
all of the above
A(n) _ is used to measure the amount of O2 in flue products.
oxygen indicator
An instrument called a clamp-on ammeter is so called because the tongs can be clamped around a single wire.
true
Air conditioning and refrigeration reversible ratchet wrenches are used to ____.
open and close refrigerant service valves
Variable speed reversible electric drills can be used to drill holes as well as tighten and loosen screws.
true
A wiring and crimping tool is used to ____.
cut and strip wire
The dial-type meter used to measure the pressure in a heating unit flue pipe is called a(n) _.
draft gauge
Which of the following tools is different from the rest with respect to the shape of the nut or screw that it turns?
hex key
A socket set is an integral part of a technician's tool box because ____.
all the above
A vacuum pump removes _ and air from a refrigeration system.
non-condensables
After brazing a joint in a very tight location, the technician would use a(n) _ to determine if the joint is properly brazed.
inspection mirror
A(n) _ is used to measure the amount of CO2 in flue products.
carbon dioxide indicator
An instrument that can be used to determine the relative humidity of air is the _.
psychrometer.
A clamp-on ammeter is designed to measure only alternating current.
true
In the thread specification 1/2-14 NPT, the NPT stands for _.
National Pipe Taper
The use of flux is always required when soldering or brazing.
False
Brazing is done at ____ soldering.
higher temperatures than
ABS and PVC pipe can be used to carry the new blended refrigerants in low temperature applications.
False
An air-acetylene unit usually consists of a B tank of acetylene gas, a regulator, a hose, and a torch.
true
DWV copper stands for drain, waste and vent and is also a lightweight copper not typically used in the HVACR industry as far as refrigerant-carrying applications are concerned.
true
The maximum temperature at which soft soldering is done is ____.
842�F
M is a lightweight copper and is not commonly used in our industry.
true
When tubing is cut with a tubing cutter, a burr is produced in the process. This slight decrease in the inside diameter of the tube can adversely affect the operation of the system.
true
In the thread specification 1/2-14 NPT, the 1/2 is the _.
thread diameter
Pipe threads are standardized by the A.N.S. A.N.S. stands for ____.
American National Standard
The proper type of flame from an oxyacetylene torch for silver brazing is ____.
neutral flame
When soldering, the technician should heat the solder with the torch to allow it to melt.
false
The size indicated for the diameter of ACR copper tubing is the ____.
outside diameter
If a technician needed 5/8" ACR for an installation and was located near only a plumbing supply house, what size and type of pipe should he ask for?
1/2" ID Copper.
The copper tubing used in the field piping of refrigeration systems is type _.
ACR
L-type copper is considered medium weight and is used most frequently.
true
The abbreviation for the plastic pipe used in systems for water and gas supply lines and irrigation systems is _.
PE
The abbreviation for the plastic pipe used in hot and cold water supply systems is _.
CPVC
When installing a refrigeration system, the piping should be connected with as few joints as possible.
true
95/5 tin-antimony solder can be used in any part of a refrigeration system.
false
The abbreviation for the plastic pipe used in systems for water drains, waste drains, and low-temperature vents is _.
ABS
When soldering, why should flux be used?
All the Above
The size indicated for the diameter of copper tubing used for plumbing is the ____.
inside diameter
When joining steel pipe, a ____ should be applied to the threads before connecting.
pipe dope
Four tools that are needed to properly prepare and thread steel pipe are the pipe cutter, reamer, threader, and _.
vice
One reason for insulation on a suction line is to help maintain the proper _.
temperature
Pipe threads, when used on pipe that will contain liquid or vapor under pressure, ____.
All the above
When soldering or brazing, the solder is ____.
melted by heat from the tubing and fitting
For cleaning ACR copper tubing before soldering, a material that can be used is ____.
sand cloth
K-type copper is heavy duty with a thick tubing wall.
True
Filler materials used in the high temperature connection of copper joints are composed of ____.
15%-60% silver
1.
Operation that causes one end of a copper tube to expand at an angle for flare nut connection to system.
Selected: g.
flaring
This answer is correct. The correct answer is:
flaring
2.
Operation of heating and cooling tubing to make it softer.
Selected:
...
The tubing or pipe for natural gas supply to a gas heating unit is _.
steel
When soldering, flux should be applied to ____.
the male part of the joint only
In the thread specification 1/2-14 NPT, the 14 stands for _.
thread per In
The abbreviation for the plastic pipe used in high pressure systems at low temperature is _.
PVC
The end of a piece of a steel pipe is reamed after it is cut with a pipe cutter to make it easier to start the thread die.
false
In order to thread steel pipe, _ is applied so friction and heat do not damage the pipe and/or cutting dies.
cutting oil
Molten solder flows between the two base metals being soldered because ____.
of capillary attraction
If a conductor carrying electrical current is formed into a coil, the magnetic field around the wire will ____.
increase
A PTC thermistor causes the resistance of the thermistor to increase when its temperature rises.
true
If two light bulbs are wired in series and one bulb burns out, the other bulb will ____.
go out
A solid state device that allows electrical energy to flow through in only one direction is called a(n) _.
diode
What type of charge does an electron have?
negative
If three bulbs are wired in parallel and one bulb burns out, the total current of the circuit will decrease.
true
The unit of measure for the current flow of electrical energy is the _.
ampere
In a circuit with two or more resistances in parallel, the total resistance in the circuit is the sum of the resistances in the circuit.
false
Copper wire sizes are measured in circular mils.
true
Ohmmeters are to be used only on circuits that are de-energized.
true
The unit of measure for resistance is the _.
ohm
Typical insulators are: ____.
glass, rubber, plastic
_ are used to measure the intensity of current flow in a circuit or a particular branch in a circuit, so they are wired in series with the circuit being evaluated.
ammeters
As loads are added in a parallel circuit, the total resistance of the circuit ____.
will decrease
A single diode can be connected as a full wave rectifier.
false
The unit of measure for the electrical pressure forcing electrical energy through a conductor is the _.
volt
If five electrons combine with three protons, the net charge will be ____.
negative
As the diameter of a wire increases, its resistance will also increase.
false
The ampere is ____.
a measure of the quantity of electrons flowing past a point in the electrical circuit in a given time
The main purpose of a rectifier is to convert direct current (DC) to alternating current (AC).
false
If a conductor carrying electrical current is formed into a coil, the strength of the magnetic field generated by the wire will increase.
true
An element in an electric heating unit is connected to a 232-V power supply. The current flow through the element is 19 A. What is the resistance of the element?
12 ?
A good conductor of electricity has few _ electrons which can move easily from one atom to another.
valence
One kilowatt of electrical energy is equal to 1,000,000 watts.
false
If there was a current flow of 6 A in a 120-V circuit, the resistance of the circuit would be _ ?.
20
What part of an atom moves from one atom to another?
electron
When checking a diode with an ohmmeter and the meter shows a resistance, if the meter leads are reversed, it should show infinity.
true
When calculating the total resistance of a parallel circuit, the result will always be lower than the lowest resistance.
true
The unit of measurement for the charge a capacitor can store is called a Joule.
false
A transformer has 10,000 turns of wire in the secondary and 100 turns in the primary. The transformer is connected to a line voltage of 120 V. The output voltage will be _ volts.
12,000
What happens to the current in a circuit if the resistance is increased?
The current decreases.
A heat sink is a device to improve the purity of the electrons in an electrical circuit.
false
In a circuit with two or more resistances in series, the total resistance in the circuit is the sum of the resistances.
true
To find the watts of electrical power in an electrical circuit, you multiply ____ together.
volts and amperes