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NATE CORE STUDY GUIDE – COMPLETE GUIDE
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NATE CORE STUDY GUIDE – COMPLETE GUIDEWhich of the following is not the product of incomplete combustion: ✔️Ans
- Oxides of nitrogen
An oil trap is required at the base of the discharge line of the vertical riser is
_____ or above ✔️Ans - 8 feet
A diode allows current to flow in one direction: ✔️Ans - True
1 Watt = _____ Btu ✔️Ans - 3.41
Current in a closed circuit is limited by which of the following: ✔️Ans -
resistance
An oil separator is located in the _____: ✔️Ans - Discharge line
______ is the heat that is absorbed or extracted when a substance changes its
state: ✔️Ans - Latent heat
_______ is the temperature at which oil starts to produce a waxy substance that
may interfere with the refrigeration system: ✔️Ans - Floc Point
1 kWh of electric power is equivalent to ______ Btu per hour: ✔️Ans - 3412
What will be the resistance in the circuit if the supply voltage is 30V and
current flowing through the circuit is 5A: ✔️Ans - 6 OHM
Gas valves operate at _____ voltage: ✔️Ans - 24V
_______ use two special helical rotors that introduce suction vapors then
compress them: ✔️Ans - Screw Compressor
A high pressure steam boiler operates at a pressure greater than ______ :
✔️Ans - 15 PSIG
In Fire tube boiler, which of the following pass through the tubes: ✔️Ans -
Flue Gas
,1 kilo watt = ______ Btu ✔️Ans - 3140 BTU
Turning the TXV valve stem in _______ direction increases super heat: ✔️Ans
- Clockwise
Which of the following compressor uses pistons, cylinders and valves to
compress the refrigerant gas: ✔️Ans - Reciprocating Compressor
Most of the heat transfer from the heat exchanger is by which of the following:
✔️Ans - Convection
Relays and contactors are ____ control switches: ✔️Ans - 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: ✔️Ans -
Daltons Law
At 32°F, 1 lb of ice can be changed to 1 lb of water by adding ____ Btu ✔️Ans
- 144 BTU
Which of the following circuit does not have multiple paths for current flow:
✔️Ans - series
Dual voltage three phase motor has _____ number of terminals ✔️Ans - 9
Which one of the following is known as the line that connects between the
metering device and the evaporator: ✔️Ans - Inlet line
Approximately _____ voltage is required for creating a spark on a spark ignition
system: ✔️Ans - 15,000V
Which one of the following in the refrigeration cycle changes the refrigerant
from low pressure gas to high pressure gas: ✔️Ans - Compressor
Heat transfer that takes place in liquids and gases in which of the following:
✔️Ans - Convection
,Which of the following is used to measure the pressure drop across the air
filter: ✔️Ans - Manometer
What will be typical range of the current sensor: ✔️Ans - 4-20 mA
RTD which measure temperature have a positive temperature coefficient:
✔️Ans - True
______ temperature is the temperature is the temperature below which
moisture condense out of air ✔️Ans - Dew Bulb
Curved boundary In Psychrometric chart indicates which of the following:
✔️Ans - Dew point temperature line
_____ is a combination of both sensible heat and latent heat: ✔️Ans -
Enthalpy
The heat energy change that is associated with a change in the phase (state)
is: ✔️Ans - Latent Heat
In water-tube boilers, pressures range from ______ : ✔️Ans - 50 to 5,000
psig
Which one of the following is used in systems for pressurizing the building:
✔️Ans - Exhaust or relief dampers
The temperature-resistance characteristic of a thermistor is _________ :
✔️Ans - Non linear
At _________ this superheated refrigerant vapor pressure and temperature is
added: ✔️Ans - Compressor
For every 1000 feet above sea level,the capacity of a natural gas furnace is de-
rated by _______ ✔️Ans - 4%
If the surrounding air is colder than the skin temperature, the body gains heat:
✔️Ans - False
, The power developed by the centrifugal pump is proportional to _________ its
speed: ✔️Ans - CUBE
Mineral oils are not to be used with HFC alternate refrigerants: ✔️Ans -
True
Flue gas temperatures at which the high-efficiency furnaces operate typically
is: ✔️Ans - 100 to 275 degrees
Which of the following type of controllers are used in HVAC applications:
✔️Ans - PI
According to ASME, safety valve of the boiler should be tested for every _____
days: ✔️Ans - 30
In Psychrometric ________ indicates which of the following: Dew point
temperature line: ✔️Ans - Chart curve boundary
1 horsepower = _________ watts: ✔️Ans - 746
Dew point temperature is the temperature at which web bulb temperature is
_________ the dry bulb temperature: ✔️Ans - Equal to
The speed of 4 pole motor is about ______ rpm: ✔️Ans - 1800
A suction line accumulator is used for which of the following purpose:
✔️Ans - 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: ✔️Ans - 5 to 7 times
Which of the following motor is best suited for speed control applications:
✔️Ans - DC Shunt motors
Square cut or butt joints are not permitted on corners of ductboard sections:
✔️Ans - True
A thermostatic expansion valve modulates to maintain suction _____: ✔️Ans
- Super Heat
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