NATE CORE EXAM 2026 PRACTICE TEST PAPER
REFRIGERATION PRINCIPLES AND ELECTRICAL
BASICS REVIEW SHEET FULL SOLUTIONS
◉ Why should hacksaws and power saws not be used when cutting
tubing or refrigerant lines? Answer: The small shavings created by
the teeth of the saw can enter the tubing and do damage to the
components of the system.
◉ Why should tube cutters be used? Answer: They produce a
square, clean cut and leave no shavings to contaminate the system.
◉ What can be used to cut capillary tubing? Answer: A triangular file
or a knife edge file.
◉ How should tubing be cut? Answer: It should be scored all the way
around the outside and then snapped to prevent closing of the inside
diameter.
◉ What can be used to remove a burr on the inside of tubing?
Answer: Reamers and deburrers.
,◉ What does burring cause on the inside of tubing? Answer: It can
create turbulence and pressure drop inside the piping.
◉ What can be used on soft drawn copper to provide a bend without
kinking or damaging the tubing? Answer: Tube benders.
◉ Spring-Type benders can only be used on what type of tubbing?
Answer: Soft drawn copper
◉ What is the purpose of a flaring tool? Answer: It allows you to join
soft drawn copper tubing without the use of a coupling.
◉ What is the purpose of a swaging tool? Answer: A method of
joining tubing without a fitting.
◉ After flaring, swaging, and connecting the tubing, what do you do
next? Answer: You either solder or braze the connection.
◉ Describe the glass stem thermometer. Answer: It has a liquid filled
tube marked off with a graduated temperature scale.
◉ What are some characteristics of a dial stem thermometer?
Answer: Not quite as accurate as the glass stem thermometer, but it
is low cost and durable.
,◉ What do the glass stem thermometer and the dial stem
thermometer measure? Answer: Dry-bulb temperature.
◉ What temperature is in relation to human comfort? Answer: Dry-
bulb temperature.
◉ What is a sling psychometer? Answer: It combines glass stem
thermometers to measure both dry-bulb and wet-bulb
temperatures.
◉ What is needed with the sling psychometer to measure
temperatures? Answer: A psychometric chart or slide rule.
◉ What can the dry-bulb and wet-bulb temperatures be used to
determine? Answer: Relative humidity (%RH) The dew points. Other
properties of the air.
◉ What can be used to calculate the relative humidity, dew point,
and other properties of the air? Answer: The difference between the
wet-bulb and the dry-bulb temperature.
◉ Explain the effects of relative humidity. Answer: By increasing the
humidity during the heating season, the evaporation of moisture is
slowed, therefore you feel warmer and vice versa.
, ◉ What is the digital psychrometer able to do? Answer: It is capable
of reading dry-bulb and wet-bulb temperature and %RH.
◉ How do you find absolute pressure? Answer: Gauge pressure +
14.7PSI
◉ What does a pressure gauge use as the operating element?
Answer: A bourdon tube.
◉ Describe the manifold gauge set. Answer: On the right = High
pressure (Liquid) (discharge gauge) (Red) On the left = Compound
or suction gauge (Blue) (Vapor)
◉ What is often used to measure pressure drop? (The difference in
pressure between two points.) Answer: Differential pressure gauges.
◉ What can differential pressure gauges do? Answer: They can
calculate air flow. They can help you determine how clean or dirty a
coil or filter is. Provides simultaneous pressure and flow
measurements
◉ Before you charge a system with refrigerant or after you have
replaced a component or repaired a leak, you should? Answer:
Remove all air and moisture from the system.
REFRIGERATION PRINCIPLES AND ELECTRICAL
BASICS REVIEW SHEET FULL SOLUTIONS
◉ Why should hacksaws and power saws not be used when cutting
tubing or refrigerant lines? Answer: The small shavings created by
the teeth of the saw can enter the tubing and do damage to the
components of the system.
◉ Why should tube cutters be used? Answer: They produce a
square, clean cut and leave no shavings to contaminate the system.
◉ What can be used to cut capillary tubing? Answer: A triangular file
or a knife edge file.
◉ How should tubing be cut? Answer: It should be scored all the way
around the outside and then snapped to prevent closing of the inside
diameter.
◉ What can be used to remove a burr on the inside of tubing?
Answer: Reamers and deburrers.
,◉ What does burring cause on the inside of tubing? Answer: It can
create turbulence and pressure drop inside the piping.
◉ What can be used on soft drawn copper to provide a bend without
kinking or damaging the tubing? Answer: Tube benders.
◉ Spring-Type benders can only be used on what type of tubbing?
Answer: Soft drawn copper
◉ What is the purpose of a flaring tool? Answer: It allows you to join
soft drawn copper tubing without the use of a coupling.
◉ What is the purpose of a swaging tool? Answer: A method of
joining tubing without a fitting.
◉ After flaring, swaging, and connecting the tubing, what do you do
next? Answer: You either solder or braze the connection.
◉ Describe the glass stem thermometer. Answer: It has a liquid filled
tube marked off with a graduated temperature scale.
◉ What are some characteristics of a dial stem thermometer?
Answer: Not quite as accurate as the glass stem thermometer, but it
is low cost and durable.
,◉ What do the glass stem thermometer and the dial stem
thermometer measure? Answer: Dry-bulb temperature.
◉ What temperature is in relation to human comfort? Answer: Dry-
bulb temperature.
◉ What is a sling psychometer? Answer: It combines glass stem
thermometers to measure both dry-bulb and wet-bulb
temperatures.
◉ What is needed with the sling psychometer to measure
temperatures? Answer: A psychometric chart or slide rule.
◉ What can the dry-bulb and wet-bulb temperatures be used to
determine? Answer: Relative humidity (%RH) The dew points. Other
properties of the air.
◉ What can be used to calculate the relative humidity, dew point,
and other properties of the air? Answer: The difference between the
wet-bulb and the dry-bulb temperature.
◉ Explain the effects of relative humidity. Answer: By increasing the
humidity during the heating season, the evaporation of moisture is
slowed, therefore you feel warmer and vice versa.
, ◉ What is the digital psychrometer able to do? Answer: It is capable
of reading dry-bulb and wet-bulb temperature and %RH.
◉ How do you find absolute pressure? Answer: Gauge pressure +
14.7PSI
◉ What does a pressure gauge use as the operating element?
Answer: A bourdon tube.
◉ Describe the manifold gauge set. Answer: On the right = High
pressure (Liquid) (discharge gauge) (Red) On the left = Compound
or suction gauge (Blue) (Vapor)
◉ What is often used to measure pressure drop? (The difference in
pressure between two points.) Answer: Differential pressure gauges.
◉ What can differential pressure gauges do? Answer: They can
calculate air flow. They can help you determine how clean or dirty a
coil or filter is. Provides simultaneous pressure and flow
measurements
◉ Before you charge a system with refrigerant or after you have
replaced a component or repaired a leak, you should? Answer:
Remove all air and moisture from the system.
