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131 Cards in this Set
- Front
- Back
- 3rd side (hint)
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The ability to utilize all types of communication skills is _______________ to the HVACR technician. |
Very important |
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It is important to be _________, ____________, and ____________ in filling out service orders so that office staff, other technicians, and customers know what work you completed on the job. |
Clear Complete Concise |
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When explaining to the customer that you adjusted the system charge, the most appropriate term is ____________. |
Refrigerant. |
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Listening carefully to what a customer is telling you: |
Can help you diagnose the problem. |
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When you arrive at the service call and meet the customer, you should: |
Listen to the customer first, then ask questions. |
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What is the volume of a room that measures 10' x 20' with an 8' ceiling |
1600cu ft |
Volume = L x W x H |
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What is the CFM requirement for an 1800ft2 house with 8' ceilings if 5 air changes are needed per hour? |
1200CFM |
CFM = (Volume x Air Changes) / 60 |
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What is the CFM requirement for an 2400ft^2 house with 8' ceilings if 5 air changes are needed per hour?
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1600CFM |
CFM = (Volume x Air Changes) /
60 |
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What is the cross-sectional area of a 10" round duct? |
79"^2 |
Area = pi x radius^2 |
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How fast does air move through a square or round duct with a velocity pressure of .2" in WC? |
1800feet/minute |
Velocity = 4005 x sqrt(Vp) |
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Customers depend on you to be: |
Honest Loyal Patient |
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Before leaving a service call, you should: |
Be sure to demonstrate system operation and describe basic maintenance procedures to the customer. |
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What are the the advantages of using a tube cutter to cut copper pipe? |
It can be used on hard or soft drawn copper, it leaves no metal shavings to contaminate the system, and it produces a clean, square cut. |
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Spring type tube benders may be used on: |
Soft drawn copper. |
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A flaring tool is used to: |
Make a mechanical joint in tubing. |
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A swagging tool is used to: |
Solder (braze) tubing without the use of couplings. |
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What is one of the advantages of a glass stem thermometer? |
It is very accurate. |
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In discussing human comfort, the temperature most commonly referred to is: |
Dry-bulb |
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A sling psychrometer uses two glass stem thermometers. One measures dry-bulb, the other measures ____________. |
Wet-bulb. |
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A standard refrigerant manifold uses what type of element to measure pressure? |
Bourdon tube. |
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What is the pressure range of a standard compound gauge on a refrigerant manifold? |
30inHg - 500psig (Over pressure or retard scale from 250 - 500psig) |
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What is the best tool for removing moisture and non-condensables from a system before adding refrigerant? |
Vacuum pump. |
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A vacuum gauge reads pressure in: |
Microns. |
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Three types of leak detection are: |
Soap bubbles Electronic Ultrasonic |
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To prevent the release of refrigerant into the atmosphere when removing it from a system, what type of equipment must be used? |
Recovery machine. |
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An anemometer uses a small fan blade to measure: |
Air velocity. |
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What is one of the benefits of using silver brazing rods for copper-to-copper joints? |
No flux is required. |
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"Housekeeping" includes: |
Disposal of waste Fire prevention and protection Proper storage of materials |
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What type of eye protection should you wear when drilling overhead? |
Goggles. |
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What agency regulates cylinders and chemicals transported in a service vehicle? |
DOT (Department of Transportation) |
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Material Safety Data Sheets (MSDS) contain: |
Information about personal protective equipment. |
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When should oxygen be used in a refrigerant system? |
Never. |
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Which classification of fire extinguisher should be used for electrical fires? |
Class C |
A- Standard combustibles (garbage, paper, etc) B- Liquids (oil, grease, solvents) C- Electrical |
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Hazardous atmospheres in confined spaces can be described as one or any combination of: |
Asphyxiating Toxic Flammable |
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"Low oxygen levels" describes a(n): |
Asphyxiating atmosphere. |
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If a ladder is placed against a wall that is 20' tall, what is the proper distance away from the wall for the base of the ladder? |
5 feet |
4:1 Rule |
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When using a ladder you should: |
Always maintain three points of contact. |
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What is the most important safety precaution that you can take when working on electrical equipment? |
Disconnect and lockout power before starting, unless testing requires the power to be on. |
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When does a Ground Fault Curcuit Interrupter (GFCI) open an electrical circuit? |
When current travels through a ground path other than neutral. |
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Proper lockout/tagout procedures state that locks places on a lockout device: |
May be removed only by the person who installed the locks. |
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A natural cooling process produced by moisture on the skin changin to low pressure steam is called: |
Evaporation. |
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During the heating season, human comfort can be enhanced without changing the temperature by: |
Adding moisture. |
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Using the cooling season, dampers on bypass humidifiers should be: |
Fully closed. |
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All matter can exist as a: |
Solid Liquid Gas |
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Stored energy is called _________ energy |
Potential |
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Heat you can feel and measure directly with a thermostat is called: |
Sensible heat. |
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The heat energy exchange associated with a pressure (state) change is called: |
Latent heat. |
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The amount of heat (BTU) needed to raise the temperature of 1lb of a substance 1 degree Fahrenheit is called the _______________ of the substance. |
Specific heat |
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The latent heat of fusion is the amount of energy required to change 1lb of a substance from the __________ phase to the __________ phase. |
Liquid Solid |
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At 32 deg F, 1lb of ice can be changed to 1lb of water by adding ___________ |
144 BTU |
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At 212 deg F, 1lb of water can be changed to 1lb of steam by adding ___________ |
970 BTU |
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When liquid and vapor phases of a substance exist together, and no more liquid can vaporize without more energy being added, the vapor is said to be: |
Saturated. |
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When a vapor is heated to a temperature higher than its saturation point, both the added heat and the temperature above saturation are called _____________ |
Super heat. |
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The process of molecules escaping from the surface of a liquid is called ____________ |
Evaporation. |
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The process of a solid turning directly into a gas without going through the liquid state is called____________ |
Sublimation. |
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The continuous movement of molecules within a liquid or a gas is called ____________ energy. |
Kinetic |
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___________ includes both latent and sensible heat energy. |
Enthalpy |
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The measurement of the force that gravity exerts is called __________ |
Weight. |
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The amount of matter in a substance is called: |
Mass. |
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The weight per unit of volume, or mass per unit of volume is called __________ |
Density. |
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Volume per unit of mass of weight is called: |
Specific volume. |
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Under standard conditions, air weighs approximately ___________ |
0.075 lbs/cu ft |
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What is the formula for converting Fahrenheit to Celsius? |
C = (F - 32) x 5/9 |
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What is the formula for converting Celsius to Fahrenheit? |
F = (C x 9/5) + 32
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Solve to find the Fahrenheit temperature corresponding to 30C |
86F |
F = (C x 9/5) + 32
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Solve to find the Fahrenheit temperature corresponding to 20C |
68F |
F = (C x 9/5) + 32
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Solve to find the Celsius temperature corresponding to 80F |
26.7C |
C = (F - 32) x 5/9
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Solve to find the Celsius temperature corresponding to 60F |
15.6C |
C = (F - 32) x 5/9
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What is the formula used to determine air volume as heat is added? |
Vf = Vi x (Tf / Ti) Where: T = Temp in F + 460 |
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What is the new volume of 1ft3 of air at 0F when heated to 100F? |
1.2ft3 |
Vf = Vi x (Tf / Ti)
Where: T = Temp in F + 460 Vf = 1 x (560 / 460) Vf = 1 x (1.2173....) Vf = 1.2 |
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The law that applies to the total pressure exerted by a mixture of gasses or vapor is: |
Dalton's Law
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A coulomb of charge is ______________ electrons. |
6.28 x 10^8 |
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A(n) _________ is a measurement of electron flow. |
Ampere |
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Voltage is best described as: |
The force that moves electrons through a circuit. |
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A substance that permits the free movement of electrons is called: |
A conductor. |
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Which conductors have the least resistance? |
Short, large diameter conductors. |
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If the voltage in a circuit is doubled, and the resistance remains the same, the current will: |
Double. |
I = E/R |
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What is th voltage of a curcuit if the resistance is 5 ohms and the current is 5A? |
25v |
E = I x R |
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A circuit has a voltage of 10v and a current of 5A. What is the resistance? |
2 ohms |
R = E/I |
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Total resistance of a series curcuit is: |
Equal to the sum of all resistances in the circuit. |
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The total current in a parallel curcuit is: |
The sum of the currents through the individual paths. |
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The rate of doing work is called __________ |
Power. |
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One Kw is equal to: |
1,000 watts |
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What is the power in a circuit that has a current of 10A and a resistance of 10ohms? |
1Kw (1,000w) |
P = I^2 x R |
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The voltage induced in each turn of the secondary coil of a transformer is: |
The same as the voltage per turn of the primary coil. |
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The load rating of a transformer is stated in: |
Volt-amperes |
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An AC induction motor consists of a stationary part called the ___________ and a rotating part called the ___________. |
Stator Rotor |
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What is the formula used to determine synchronous speed of a three phase motor? |
RPM = (Hz x 120) / # of poles |
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What is the synchronous speed of a three phase motor that has 6 poles and is operating on a 60Hz alternating current? |
1200RPM |
RPM = (Hz x 120) / # of poles
RPM = (60 x 120) / 6 RPM = 7200 / 6 RPM = 1200 |
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How does the power factor of an inductive motor affect efficiency? |
The lower the power factor, the less efficient the motor is. |
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Which single phase AC motor does not have a start winding? |
Shaded-pole |
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A centrifugal switch opens the start winding curcuit when a capacitor-start motor reaches _________ of full speed. |
75-80% |
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A run capacitor is always connected to the _______ and ________ terminals. |
Start Run |
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Terminal number 1 on all potential relays is always connected to the _____________. |
Start capacitor. |
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The coil of a voltage relay is located between terminals _____________ of the relay. |
2 and 5 |
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What type of AC motor has the highest starting torque and the greatest efficiency? |
Three phase |
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How many terminals does a dual-voltage three phase motor have? |
9 |
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The primary function of any wiring diagram is: |
To aid the technician in finding the problem. |
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How many functions is an individual circuit in a control system designed to control? |
One |
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The five basic components of all schematics are: |
A power supply A path A load A switch A legend |
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The intention of the overall schematic is: |
To show how the curcuit functions. |
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The type of schematic that provides the most helpful troubleshooting information for the service technician is a: |
Ladder diagram. |
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Devices that consume power and convert it to some other form of energy, such as motion or heat, are called: |
Loads. |
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The normal dividing lines for voltage changes in a schematic is the: |
Transformer. |
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The part of the schematic that lists and explains the system components is called the _________. |
Legend. |
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Relays and contractors are ______________ control switches |
Electrically controlled |
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A _____________ allows the same current to flow through all of the components. |
Series circuit |
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A _______________ has multiple paths for current flow. |
Parallel circuit |
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That types of circuits are primarily used in control and safety applications? |
Series. |
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When testing with a voltmeter, you should: |
Place the meter in parallel with the curcuit being tested. |
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What does a resistance of 0 ohms across a circuit indicate? |
There is a short. |
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When you use an ohmmeter, the circuit being tested: |
Must be isolated from all energy sources. |
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When you test a switch with an ohmmeter, a reading of 0 ohms indicates the switch is ________. |
Closed. |
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On all meters, digital and analog, the scale used should indicate the measurement: |
Close to the middle of the range. |
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When testing across a closed switch in an energized circuit, you should read: |
0VAC |
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When using a standard clamp on ammeter, you should: |
Make sure the jaws are closed before taking a reading. |
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When testing compressor windings, you take the following readings: C to R: 2 ohms C to S: infinite resistance C to R: infinite resistance What is the diagnosis? |
Start winding is open. |
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Capacitance meters must be used on capacitors that: |
Have been removed from the circuit. |
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When testing a thermostat wire that has been removed from the curcuit, you measure 0 ohms between red and white. |
This indicates that there is a short. |
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When testing with an ammeter, you should place the meter: |
In series with the circuit being tested. |
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How do you calculate PSIA? |
PSIG + 14.7 |
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In Ohm's law, the variables P, I, E, and R, are used to represent different electrical terms. What does each represent? |
P - watts I - amperes E - volts R - resistance |
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How do you calculate the cross sectional area of a rectangular or square duct? |
Length (in feet) x Width (in feet) |
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How do you calculate the cross sectional area of a round duct?
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Area = pi x radius^2 |
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How do you determine the required CFM for a building or room based on number of air changes needed per hour? |
(Volume x #of air changes needed) / 60 Volume = L x W x H |
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How do you determine duct air velocity (in FPM) using velocity pressure as a known variable? |
Velocity = 4005 x sqrt Vp |
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How do you calculate CFM using duct air velocity and duct cross sectional area as known variables? |
CFM = V x A |
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How do you maintain consistent duct cross sectional area in scenarios where the width or height must be adjusted, such as to fit through an obstacle? |
H1 x W1 = H2 x W2 H1 and W1 are the dimensions of the original duct. |
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Which schematic is useful for quickly visualizing each component? |
Pictorial schematic. |
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In order for an agreement to be legally binding, it must be ___________. |
In writing. |
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To change the direction of a fan run by a three phase induction motor, you must _____________. |
Switch two of the leads into opposite positions. If the system has a "high leg" only switch the two "low legs". |
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