NATE Air Distribution Review QUESTIONS WITH COMPLETE VERIFIED SOLUTIONS 2024/2025, Exams of Physics

Download NATE Air Distribution Review QUESTIONS WITH COMPLETE VERIFIED SOLUTIONS 2024/2025 and more Exams Physics in PDF only on Docsity!

NATE Air Distribution Review QUESTIONS WITH

COMPLETE VERIFIED SOLUTIONS 2024/

<question: The density of air is A: How much air weighs per cubic foot B: How much volume one pound of air occupies C: The ratio of the weight of water to that of the same volume of water D: The ratio of the amount of water vapor contained in a cu. ft. of air to the amount of moisture held at saturation A: How much air weighs per cubic foot The specific volume of air is A: How much air weighs per cubic foot B: How much volume one pound of air occupies C: The ratio of the weight of water to that of the same volume of water D: The ratio of the amount of water vapor contained in a cu. ft. of air to the amount of moisture held at saturation B: How much volume one pound of air occupies The relative humidity of air is A: The percent of moisture air is holding as opposed to the amount it could hold if it were saturated B: Always less than 100%

C: The most accurate measurement of how much water vapor is in a given body of air D: Used as a multiplier to size humidifiers A: The percent of moisture air is holding as opposed to the amount it could hold if it were saturated As air is heated it A: Contracts B: Expands C: Does not change its volume D: Becomes more dense B: Expands The air pressure in a sealed balloon is A: Static pressure B: Velocity pressure C: A combination of static and velocity pressures D: None of the above A: Static pressure A blower connected to a length of duct A: Creates static pressure which is then converted to velocity pressure B: Creates velocity pressure directly

C: Creates resistance to the flow of air D: None of the above A: Creates static pressure which is then converted to velocity pressure Velocity pressure is determined by A: Subtracting static pressure from total pressure B: Subtracting total pressure from static pressure C: Dividing the total pressure by the static pressure D: Subtracting the traverse pressure from the velocity A: Subtracting static pressure from total pressure Velocity pressure can be mathematically converted to A: CFM B: FPM C: Relative humidity D: Inches of mercury vacuum B: FPM fpm = 4005 x (sqrt of Vp) An inclined manometer is basically A: A U-tube manometer tilted at a steep angle

B: A hygrometer on a stand C: A digital micron gauge D: A type of sling psychrometer A: A U-tube manometer tilted at a steep angle A duct measures 24 inches by 18 inches. The air velocity is 600 FPM. How many CFM are being delivered through the duct? Round the number to the nearest whole number A: 1600 CFM B: 1800 CFM C: 2000 CFM D: 2200 CFM B: 1800 CFM V = cfm/A V = velocity in fpm AV = (cfm/A)A A = Area in sqft AV = cfm 3 x 600 = 1800 The static pressure of a duct is 1.76 inches and the total pressure is 2 inches. What is the velocity pressure? A: .024 inches B: .24 inches

C: 3.76 inches D: zero B: .24 inches Tp = Sp + Vp A pitot tube can directly measure A: Total and velocity pressures B: Total and static pressures C: Velocity and static pressures D: None of the above B: Total and static pressures Which of the following is the best description of a duct traverse? A: A series of carefully spaced velocity pressure readings which may be converted to fpm using an equation B: A series of carefully spaced velocity pressure readings which may be converted directly to cfm using an equation C: A series of carefully spaced static pressure readings which may be converted to fpm using an equation D: A series of carefully spaced static pressure readings which may be converted to cfm using an equation A: A series of carefully spaced velocity pressure readings which may be converted to fpm using an equation How many holes must be made in a round duct in order to take a series of traverse readings?

A: One B: Two C: Three D: Four B: Two A thermo-anemometer measures A: CFM directly B: FPM directly C: Total and static pressures directly D: Temperature and humidity B: FPM directly The dew point temperature is A: The temperature at which water vapor in the air will condense into a liquid B: The temperature at which air gives up its moisture C: The saturation temperature of water vapor in a body of air D: All of the above D: All of the above Dehumidification occurs when an air conditioning coil

A: Operates at or below the dew point of the air moving across it B: Operates above dew point C: The cooling coil always removes moisture as long as it is operating D: Cooling coils do not dehumidify air A: Operates at or below the dew point of the air moving across it Who usually determines if a duct leakage test is to be performed and the test pressure at which it will be performed? A: The design engineer B: The installing contractor C: The TAB technician D: The sheet metal foreman A: The design engineer When testing a duct system to determine its leakage rate, why is a special test stand necessary? A: It contains a calibrated orifice and matching flow chart for that orifice B: It is manufactured to accepted testing standards C: Test results can be traced to the specific test stand used for the test if there are concerns about accuracy D: All of the above D: All of the above

Why are two manometers mounted on a duct leakage test stand? A: To use one as a spare in case something happens to the other B: To be checked for accuracy against each other C: To speed up the testing procedure D: None of these are correct D: None of these are correct When the dry bulb temperature increases, the relativity humidity of air A: Increases B: Decreases C: Remains the same D: None of these B: Decreases When the dry bulb temperature increases, the wet bulb temperature A: Increases B: Decreases C: Remains the same D: None of these A: Increases

When the dry bulb temperature increases, the dew point temperature A: Increases B: Decreases C: Remains the same D: None of these C: Remains the same When the dry bulb temperature increases, the specific humidity A: Increases B: Decreases C: Remains the same D: None of these C: Remains the same When the dry bulb temperature increases, the specific volume of the air A: Increases B: Decreases C: Remains the same D: None of these A: Increases

When the dry bulb temperature increases, the density of air A: Increases B: Decreases C: Remains the same D: None of these B: Decreases There are _________ grains of water vapor per pound of water. A: 0. B: 13. C: 3. D: 7000 D: 7000 There are _________ pounds per cubic foot of air. A: 0. B: 13. C: 3. D: 7000 A: 0.

The cfm per ton rate for normal comfort cooling is approximately A: 250 cfm/ton B: 300 cfm/ton C: 400 cfm/ton D: 500 cfm/ton C: 400 cfm/ton Cooling air raises its A: Specific humidity B: Relative humidity C: Dew point D: None of these B: Relative humidity Air with a dry bulb temperature of 60 degrees and a wet bulb temperature of 60 degrees has a relative humidity of A: 0% B: 50% C: 100% D: The answer cannot be determined without a psychrometric chart

C: 100%

Air with a dry bulb temperature of 60 degrees and a wet bulb temperature of 60 degrees has a dew point temperature of A: 50 degrees B: 60 degrees C: 70 degrees D: The answer cannot be determined without a psychrometric chart C: 60 degrees A sensible heat factor of 1.0 means that ________ are (is) being removed. A: Grains B: Water vapor C: Moisture D: None of these D: None of these Decreasing the CFM over an evaporator will _______ the moisture removal from the air. A: Increase B: Decrease C: Not change

D: None of these A: Increase A rotating Velometer measures A: CFM B: FPM C: RPM D: Feet D: Feet Return air grilles are not to be installed in A: Bedrooms B: Bathrooms or kitchens C: Hallways D: Living rooms B: Bathrooms or kitchens The proper amount of air in CFM for each room is determined by A: Rules of thumb B: A detailed room-by-room heat load calculation C: The size of the ducts

D: Local building code B: A detailed room-by-room heat load calculation On residential duct installations the accepted method of attaching duct sections to each other is A: Welding them B: Using the slip and drive method C: The bolted flange method D: Slip fit with a suitable sealant B: Using the slip and drive method Which of the following is not an acceptable location for a thermostat? A: Five feet off the floor on an inside wall B: Five feet off the floor on an outside wall C: Near a return air register D: In the most central location of the home B: Five feet off the floor on an outside wall What is the difference between "accuracy" and "precision" when applied to instruments? A: Accuracy means the instrument gets the same reading each time it is used to measure the same value. Precision means the instrument is correctly calibrated. B: Accuracy is a measure of how close the measurement is to being correct. Precision is the measure of how small a value the instrument can detect. C: Accuracy is a measure of how small a value the instrument can detect. Precision is a measure of the

ability of the instrument to obtain the same reading when taking the reading a second or third time. D: Accuracy and precision mean exactly the same thing. B: Accuracy is a measure of how close the measurement is to being correct. Precision is the measure of how small a value the instrument can detect. The range of an instrument is A: The difference between the lowest and highest readings the instrument can measure B: The smallest increment of measurement the instrument is capable of measuring C: The difference between the cut-in and cut-out D: The highest value the instrument can measure without damage to the instrument A: The difference between the lowest and highest readings the instrument can measure A duct with an inside area of 4 square feet has a velocity of 1000 feet per minute. How many CFM of air are moving through that section of the duct? A: 1000 CFM B: 2000 CFM C: 4000 CFM D: 6000 CFM C: 4000 CFM CFM = V x A CFM = 1000 X 4 = 4000 A 32-inch by 32-inch square duct is to be changed to a height of 28 inches so it will fit around an obstruction in a boiler room. How wide must the duct be in order to maintain the same area? Round

the number off to the nearest whole number of inches. A: 36 inches B: 37 inches C: 38 inches D: 39 inches B: 37 inches 32 X 32 = H X 28 1024 = H 1024/28 = H28/ 36.57 = H Which of the following is not a sheet metal duct fitting? A: Register boot B: End boot C: 90 degree half union D: Starting collar C: 90 degree half union Which of the following is a true statement? A: The greater the velocity, the more resistance there is to a change in direction B: If the duct area decreases, the velocity increases C: When a fitting creates turbulence, the turbulence continues for several feet down the duct

D: All of these are correct statements D: All of these are correct statements Which of the following is not a duct system type? A: Radial duct system B: Parameter duct system C: Extended plenum system D: Equal friction system D: Equal friction system A 24-inch by 8-inch rectangular duct has an aspect ratio of A: 1:1 ratio B: 2:1 ratio C: 3:1 ratio D: 4:1 ratio C: 3:1 ratio The most efficient method of air balancing a duct system is A: The equal temperature method B: The sequential method C: The proportional method

D: The flow hood method C: The proportional method Which of the following types of turning vanes produce the least dynamic system loss? A: Single wall vanes B: Double wall vanes C: Heel and cheek vanes D: Not using turning vanes at all A: Single wall vanes Which of the following equations is used to determine the actual operating capacity of a system? A: BTUH = 1.08 x CFM x TD between the return and supply air B: BTUH = 4.5 x CFM x The difference in enthalpy between the return and supply air C: BTU = specific heat of air x pounds of air x TD D: None of these B: BTUH = 4.5 x CFM x The difference in enthalpy between the return and supply air