FDNY A-35 | Actual Exam Questions and Answers with complete
Solutions | Updated 2025
Question 1
Air compressors are commonly used to power which two of the following?
A) Hydraulic lifts and electric welders
B) Industrial equipment and construction tools
C) Diesel engines and steam turbines
D) Ventilation fans and water pumps
E) Computer servers and lighting systems
Correct Answer: B) Industrial equipment and construction tools
Rationale: Air compressors provide pressurized air, which is a versatile power source for a
wide range of applications, including pneumatic tools used in construction (like nail guns
and jackhammers) and various types of industrial equipment.
Question 2
Which of the following is an example of equipment that is typically powered by an air
compressor?
A) An electric drill
B) A hydraulic car jack
C) Lifts in auto service stations
D) A soldering iron
E) A microwave oven
Correct Answer: C) Lifts in auto service stations
Rationale: Pneumatic (air-powered) lifts are commonly used in automotive service stations
to raise vehicles. They are powered by the high-pressure air supplied by an air compressor.
Question 3
A Certificate of Fitness (A-35) permit is required to supervise an air compressor that operates at
a pressure above what level?
A) 50 PSI
B) 75 PSI
C) 100 PSI
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D) 125 PSI
E) 150 PSI
Correct Answer: C) 100 PSI
Rationale: The regulations require a permitted and certified individual to supervise the
operation of any air compressor that is capable of compressing air to a pressure greater
than 100 pounds per square inch (PSI).
Question 4
Reciprocating, centrifugal, solar, and rotary are all types of:
A) Air compressor power sources
B) Air compressor safety devices
C) Air compressor cooling systems
D) Air compressors
E) Air compressor maintenance procedures
Correct Answer: D) Air compressors
Rationale: These terms describe the different mechanical methods that air compressors use
to compress air. The most common type is the reciprocating compressor.
Question 5
How does an air compressor work?
A) It heats air to increase its pressure.
B) It forces ambient air into a container under pressure.
C) It mixes air with fuel to create a combustible mixture.
D) It uses a fan to move large volumes of air.
E) It removes moisture from the air to decrease its volume.
Correct Answer: B) It forces ambient air into a container under pressure.
Rationale: The fundamental principle of an air compressor is to take in atmospheric air and
mechanically reduce its volume by forcing it into a storage tank (receiver). As more air is
forced into the fixed volume of the tank, the pressure increases.
Question 6
To prevent the ignition of flammable gases that are heavier than air and may accumulate on the
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floor, an air compressor should be:
A) Placed directly on the floor for stability.
B) Raised at least 5 feet above ground level.
C) Cooled with a water spray system.
D) Operated only in well-ventilated outdoor areas.
E) Encased in a fireproof box.
Correct Answer: B) Raised at least 5 feet above ground level.
Rationale: Flammable vapors from substances like gasoline are often heavier than air and
can collect near the floor. Since air compressors generate heat and potential sparks, they
must be elevated to prevent their air intake from drawing in these explosive vapors.
Question 7
In a reciprocating air compressor, what components make up the compression chamber?
A) A fan and a housing
B) A turbine and a rotor
C) A piston inside a cylinder
D) Two meshing screws
E) A diaphragm and a valve
Correct Answer: C) A piston inside a cylinder
Rationale: The reciprocating compressor, similar to an internal combustion engine, uses a
piston that moves up and down within a cylinder to draw in, compress, and discharge the
air.
Question 8
In a single-stage reciprocating compressor, what happens when the piston moves down?
A) Air is compressed and forced into the receiver.
B) The discharge valve opens.
C) The intake valve opens, and air is drawn into the cylinder.
D) The piston cools down.
E) The motor shuts off.
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Correct Answer: C) The intake valve opens, and air is drawn into the cylinder.
Rationale: The downward stroke of the piston creates a vacuum inside the cylinder, which
causes the intake valve to open and allows atmospheric air to be drawn in, filling the
chamber.
Question 9
What is the function of the discharge valve on an air compressor?
A) It allows air to be drawn into the cylinder.
B) It releases compressed air from the cylinder into the air receiver.
C) It acts as a safety valve to release excess pressure.
D) It drains moisture from the system.
E) It allows the motor to start without a load.
Correct Answer: B) It releases compressed air from the cylinder into the air receiver.
Rationale: After the piston moves up and compresses the air, the pressure inside the
cylinder becomes high enough to force open the spring-loaded discharge valve, allowing the
compressed air to exit the cylinder and enter the storage tank (air receiver).
Question 10
What is a key feature of a multi-stage air compressor?
A) It has only one large piston.
B) It uses an electric motor instead of a gas engine.
C) It has more than one piston and cylinder, and each stage increases the air pressure.
D) It does not require an air receiver tank.
E) It does not generate any heat during compression.
Correct Answer: C) It has more than one piston and cylinder, and each stage increases the
air pressure.
Rationale: A multi-stage compressor achieves higher pressures by compressing the air in a
series of steps. The discharge from the first cylinder is fed into the intake of the second,
smaller cylinder, where it is compressed to an even higher pressure.
Question 11
As air is compressed, it becomes heated. What component is used in a multi-stage compressor to
Solutions | Updated 2025
Question 1
Air compressors are commonly used to power which two of the following?
A) Hydraulic lifts and electric welders
B) Industrial equipment and construction tools
C) Diesel engines and steam turbines
D) Ventilation fans and water pumps
E) Computer servers and lighting systems
Correct Answer: B) Industrial equipment and construction tools
Rationale: Air compressors provide pressurized air, which is a versatile power source for a
wide range of applications, including pneumatic tools used in construction (like nail guns
and jackhammers) and various types of industrial equipment.
Question 2
Which of the following is an example of equipment that is typically powered by an air
compressor?
A) An electric drill
B) A hydraulic car jack
C) Lifts in auto service stations
D) A soldering iron
E) A microwave oven
Correct Answer: C) Lifts in auto service stations
Rationale: Pneumatic (air-powered) lifts are commonly used in automotive service stations
to raise vehicles. They are powered by the high-pressure air supplied by an air compressor.
Question 3
A Certificate of Fitness (A-35) permit is required to supervise an air compressor that operates at
a pressure above what level?
A) 50 PSI
B) 75 PSI
C) 100 PSI
,[Type here]
D) 125 PSI
E) 150 PSI
Correct Answer: C) 100 PSI
Rationale: The regulations require a permitted and certified individual to supervise the
operation of any air compressor that is capable of compressing air to a pressure greater
than 100 pounds per square inch (PSI).
Question 4
Reciprocating, centrifugal, solar, and rotary are all types of:
A) Air compressor power sources
B) Air compressor safety devices
C) Air compressor cooling systems
D) Air compressors
E) Air compressor maintenance procedures
Correct Answer: D) Air compressors
Rationale: These terms describe the different mechanical methods that air compressors use
to compress air. The most common type is the reciprocating compressor.
Question 5
How does an air compressor work?
A) It heats air to increase its pressure.
B) It forces ambient air into a container under pressure.
C) It mixes air with fuel to create a combustible mixture.
D) It uses a fan to move large volumes of air.
E) It removes moisture from the air to decrease its volume.
Correct Answer: B) It forces ambient air into a container under pressure.
Rationale: The fundamental principle of an air compressor is to take in atmospheric air and
mechanically reduce its volume by forcing it into a storage tank (receiver). As more air is
forced into the fixed volume of the tank, the pressure increases.
Question 6
To prevent the ignition of flammable gases that are heavier than air and may accumulate on the
,[Type here]
floor, an air compressor should be:
A) Placed directly on the floor for stability.
B) Raised at least 5 feet above ground level.
C) Cooled with a water spray system.
D) Operated only in well-ventilated outdoor areas.
E) Encased in a fireproof box.
Correct Answer: B) Raised at least 5 feet above ground level.
Rationale: Flammable vapors from substances like gasoline are often heavier than air and
can collect near the floor. Since air compressors generate heat and potential sparks, they
must be elevated to prevent their air intake from drawing in these explosive vapors.
Question 7
In a reciprocating air compressor, what components make up the compression chamber?
A) A fan and a housing
B) A turbine and a rotor
C) A piston inside a cylinder
D) Two meshing screws
E) A diaphragm and a valve
Correct Answer: C) A piston inside a cylinder
Rationale: The reciprocating compressor, similar to an internal combustion engine, uses a
piston that moves up and down within a cylinder to draw in, compress, and discharge the
air.
Question 8
In a single-stage reciprocating compressor, what happens when the piston moves down?
A) Air is compressed and forced into the receiver.
B) The discharge valve opens.
C) The intake valve opens, and air is drawn into the cylinder.
D) The piston cools down.
E) The motor shuts off.
, [Type here]
Correct Answer: C) The intake valve opens, and air is drawn into the cylinder.
Rationale: The downward stroke of the piston creates a vacuum inside the cylinder, which
causes the intake valve to open and allows atmospheric air to be drawn in, filling the
chamber.
Question 9
What is the function of the discharge valve on an air compressor?
A) It allows air to be drawn into the cylinder.
B) It releases compressed air from the cylinder into the air receiver.
C) It acts as a safety valve to release excess pressure.
D) It drains moisture from the system.
E) It allows the motor to start without a load.
Correct Answer: B) It releases compressed air from the cylinder into the air receiver.
Rationale: After the piston moves up and compresses the air, the pressure inside the
cylinder becomes high enough to force open the spring-loaded discharge valve, allowing the
compressed air to exit the cylinder and enter the storage tank (air receiver).
Question 10
What is a key feature of a multi-stage air compressor?
A) It has only one large piston.
B) It uses an electric motor instead of a gas engine.
C) It has more than one piston and cylinder, and each stage increases the air pressure.
D) It does not require an air receiver tank.
E) It does not generate any heat during compression.
Correct Answer: C) It has more than one piston and cylinder, and each stage increases the
air pressure.
Rationale: A multi-stage compressor achieves higher pressures by compressing the air in a
series of steps. The discharge from the first cylinder is fed into the intake of the second,
smaller cylinder, where it is compressed to an even higher pressure.
Question 11
As air is compressed, it becomes heated. What component is used in a multi-stage compressor to
