NATE CORE STUDY GUIDE(correct answers)to pass

NATE CORE STUDY GUIDE(correct answers)to passWhich of the following is not the product of incomplete combustion: Oxides of nitrogen An oil trap is required at the base of the discharge line of the vertical riser is _____ or above 8 feet A diode allows current to flow in one direction: True 1 Watt = _____ Btu 3.41 Current in a closed circuit is limited by which of the following: resistance An oil separator is located in the _____: Discharge line ______ is the heat that is absorbed or extracted when a substance changes its state: Latent heat _______ is the temperature at which oil starts to produce a waxy substance that may interfere with the refrigeration system: Floc Point 1 kWh of electric power is equivalent to ______ Btu per hour: 3412 What will be the resistance in the circuit if the supply voltage is 30V and current flowing through the circuit is 5A: 6 OHM Gas valves operate at _____ voltage: 24V _______ use two special helical rotors that introduce suction vapors then compress them: Screw Compressor A high pressure steam boiler operates at a pressure greater than ______ : 15 PSIG In Fire tube boiler, which of the following pass through the tubes: Flue Gas 1 kilo watt = ______ Btu 3140 BTU Turning the TXV valve stem in _______ direction increases super heat: Clockwise Which of the following compressor uses pistons, cylinders and valves to compress the refrigerant gas: Reciprocating Compressor Most of the heat transfer from the heat exchanger is by which of the following: Convection Relays and contactors are ____ control switches: Electrically Operated Which of the following law states that the total pressure of a confined mixture of gases is the sum of pressures of each of the gases in the mixture: Daltons Law At 32°F, 1 lb of ice can be changed to 1 lb of water by adding ____ Btu 144 BTU Which of the following circuit does not have multiple paths for current flow: series Dual voltage three phase motor has _____ number of terminals 9 Which one of the following is known as the line that connects between the metering device and the evaporator: Inlet line Approximately _____ voltage is required for creating a spark on a spark ignition system: 15,000V Which one of the following in the refrigeration cycle changes the refrigerant from low pressure gas to high pressure gas: Compressor Heat transfer that takes place in liquids and gases in which of the following: Convection Which of the following is used to measure the pressure drop across the air filter: Manometer What will be typical range of the current sensor: 4-20 mA RTD which measure temperature have a positive temperature coefficient: True ______ temperature is the temperature is the temperature below which moisture condense out of air Dew Bulb Curved boundary In Psychrometric chart indicates which of the following: Dew point temperature line _____ is a combination of both sensible heat and latent heat: Enthalpy The heat energy change that is associated with a change in the phase (state) is: Latent Heat In water-tube boilers, pressures range from ______ : 50 to 5,000 psig Which one of the following is used in systems for pressurizing the building: Exhaust or relief dampers The temperature-resistance characteristic of a thermistor is _________ : Non linear At _________ this superheated refrigerant vapor pressure and temperature is added: Compressor For every 1000 feet above sea level,the capacity of a natural gas furnace is de-rated by _______ 4% If the surrounding air is colder than the skin temperature, the body gains heat: False The power developed by the centrifugal pump is proportional to _________ its speed: CUBE Mineral oils are not to be used with HFC alternate refrigerants: True Flue gas temperatures at which the high-efficiency furnaces operate typically is: 100 to 275 degrees Which of the following type of controllers are used in HVAC applications: PI According to ASME, safety valve of the boiler should be tested for every _____ days: 30 In Psychrometric ________ indicates which of the following: Dew point temperature line: Chart curve boundary 1 horsepower = _________ watts: 746 Dew point temperature is the temperature at which web bulb temperature is _________ the dry bulb temperature: Equal to The speed of 4 pole motor is about ______ rpm: 1800 A suction line accumulator is used for which of the following purpose: Prevent liquid refrigerant from entering compressor Locked Rotor Ampere (LRA) current of a motor will be typically ________ times the normal running current of the motor: 5 to 7 times Which of the following motor is best suited for speed control applications: DC Shunt motors Square cut or butt joints are not permitted on corners of ductboard sections: True A thermostatic expansion valve modulates to maintain suction _____: Super Heat An amperage is the measurement of which of the following: Current A ______ is used to control the flow of refrigerant in an air conditioning or refrigeration system: Solenoid valve Which of the following is not available in heat pump: low pressure sensing switch Which of the following will never get energized during defrost mode in a heat pump: Outdoor Fan _______ is the cubic feet of the mixture per pound of dry air: Specific Volume Which of the following motors are more rugged and can handle more load: Ball bearing type motors ________ compressors operate most efficiently with a high molecular weight, high specific volume refrigerant: Centrifugal The minimum Annual Fuel Utilization Efficiency (AFUE) available is set by federal law for most furnace types at _______ : 78% ______ of a fan is the total pressure diminished by the fan velocity pressure: Static Pressure Suction pressure at the ________ is governed by the design of the evaporator: Compressor Which of the following compressors have pulsations: Reciprocal Compressors When a system is circulating an excessive amount of oil, the oil indicator may become saturated. This results in the indicator to appear in _______ color Brown The horsepower required for any fan or blower varies directly as the ______ of the speed: Cube With increase in evaporator load, the liquid refrigerant evaporates at _____ rate: Faster The purpose of an accumulator is to prevent ______ damage due to slugging of refrigerant and oil: Compressor Higher the suction pressure, the greater the efficiency of the _______: Compressor The refrigerant holding capacity of the accumulator is based on an average conditions of ______ percent fill under running conditions: 65%