NATE Air Distribution exam with 100% correct answers

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