A-35 Air Compressor and Certificate of
Fitness Practice Exam – Updated 2026
(Graded A+)
Subject: Air Compressor Operations and Safety (A-35 Certificate of Fitness)
Subtopic: Safety Regulations, Pressure Vessel Components, and Operational Standards
Question 1: Which of the following is the primary responsibility of the holder of an A-35
Certificate of Fitness regarding the daily operation of an air compressor system?
A) Conducting a complete hydrostatic pressure test of the receiver tank every 24 hours.
B) Verifying that all safety devices, including pressure relief valves and gauges, are functional
and within inspection limits.
C) Replacing the compressor piston rings and seals to maintain optimal volumetric efficiency.
D) Calibrating the digital programmable logic controller (PLC) to automate shutdown
procedures.
Correct Answer: B - Verifying that all safety devices, including pressure relief valves and
gauges, are functional and within inspection limits.
Rationale: The A-35 certificate holder is tasked with the safe operation and routine monitoring
of the system. Ensuring safety devices (like pressure relief valves) are operational is critical for
preventing catastrophic vessel failure. Option A is incorrect because hydrostatic tests are
periodic, not daily. Option C is a maintenance task for a qualified technician, not an operational
daily requirement. Option D is beyond the scope of a standard A-35 operator.
Question 2: An air compressor receiver tank is rated for a Maximum Allowable Working
Pressure (MAWP) of 150 PSI. At what pressure should the safety relief valve be set to discharge
to ensure the safety of the vessel?
A) Exactly 150 PSI.
B) Slightly above 150 PSI, but not to exceed the vessel's design limitations.
C) 200 PSI to allow for operational spikes during heavy tool usage.
D) 125 PSI to provide a safety buffer.
Correct Answer: B - Slightly above 150 PSI, but not to exceed the vessel's design limitations.
,Rationale: Safety valves are designed to prevent the pressure from exceeding the MAWP. Setting
it exactly at 150 PSI could cause nuisance tripping due to normal operating fluctuations, but
setting it too high (Option C) creates a significant explosion risk. Option D would cause the
valve to vent prematurely during normal operation.
Question 3: During a routine inspection, you observe that the pressure gauge needle is oscillating
rapidly. What is the most likely cause, and what action should be taken?
A) This is normal behavior for compressors; no action is required.
B) The compressor is undersized for the load; increase the RPM to compensate.
C) It indicates a potential issue with the dampening mechanism or pressure fluctuations; report it
for immediate inspection or repair.
D) The receiver tank is over-pressurized; bleed the tank manually.
Correct Answer: C - It indicates a potential issue with the dampening mechanism or
pressure fluctuations; report it for immediate inspection or repair.
Rationale: A rapidly oscillating needle (chatter) indicates either a mechanical issue with the
gauge or instability in the air line pressure. Ignoring this (Option A) is unsafe. Increasing RPM
(Option B) could cause mechanical failure, and bleeding the tank (Option D) does not address
the faulty instrumentation.
Question 4: Where must the A-35 Certificate of Fitness be kept during the operation of an air
compressor?
A) Secured in the central office safe.
B) Posted at the primary location where the air compressor is being operated or kept readily
available for inspection.
C) Kept in the operator's personal vehicle.
D) It only needs to be produced if an accident occurs.
Correct Answer: B - Posted at the primary location where the air compressor is being
operated or kept readily available for inspection.
Rationale: Regulatory compliance dictates that certificates of fitness must be readily available at
the site of operation to demonstrate the competence of the person currently in charge of the
equipment.
Question 5: What is the primary purpose of the condensate drain valve located at the bottom of
the air receiver tank?
, A) To maintain constant tank temperature.
B) To allow the compressor to cycle faster.
C) To remove accumulated water and oil to prevent corrosion and tank explosion.
D) To lubricate the internal walls of the receiver tank.
Correct Answer: C - To remove accumulated water and oil to prevent corrosion and tank
explosion.
Rationale: Compressed air contains moisture. If not drained, this moisture accumulates at the
bottom of the tank, causing internal corrosion (thinning the metal), which significantly weakens
the structural integrity of the pressure vessel.
Question 6: If an air compressor is being used in an area where flammable vapors may be
present, which of the following is a mandatory precaution?
A) The compressor must be fitted with an explosion-proof motor and specialized intake
filtration.
B) The compressor must be operated only at night.
C) The compressor should be kept running continuously to ensure air turnover.
D) No special precautions are needed if the compressor is outdoors.
Correct Answer: A - The compressor must be fitted with an explosion-proof motor and
specialized intake filtration.
Rationale: Standard electric motors can produce sparks during startup or operation, which can
ignite flammable vapors. Using standard equipment in a hazardous environment is a major
fire/explosion risk.
Question 7: A fusible plug is sometimes found on air compressor systems. What is its function?
A) To regulate the flow of compressed air to the distribution manifold.
B) To melt at a predetermined high temperature, releasing pressure if a fire occurs or the
compressor overheats.
C) To act as a secondary check valve for the oil lubrication system.
D) To measure the vibrations of the compressor head.
Fitness Practice Exam – Updated 2026
(Graded A+)
Subject: Air Compressor Operations and Safety (A-35 Certificate of Fitness)
Subtopic: Safety Regulations, Pressure Vessel Components, and Operational Standards
Question 1: Which of the following is the primary responsibility of the holder of an A-35
Certificate of Fitness regarding the daily operation of an air compressor system?
A) Conducting a complete hydrostatic pressure test of the receiver tank every 24 hours.
B) Verifying that all safety devices, including pressure relief valves and gauges, are functional
and within inspection limits.
C) Replacing the compressor piston rings and seals to maintain optimal volumetric efficiency.
D) Calibrating the digital programmable logic controller (PLC) to automate shutdown
procedures.
Correct Answer: B - Verifying that all safety devices, including pressure relief valves and
gauges, are functional and within inspection limits.
Rationale: The A-35 certificate holder is tasked with the safe operation and routine monitoring
of the system. Ensuring safety devices (like pressure relief valves) are operational is critical for
preventing catastrophic vessel failure. Option A is incorrect because hydrostatic tests are
periodic, not daily. Option C is a maintenance task for a qualified technician, not an operational
daily requirement. Option D is beyond the scope of a standard A-35 operator.
Question 2: An air compressor receiver tank is rated for a Maximum Allowable Working
Pressure (MAWP) of 150 PSI. At what pressure should the safety relief valve be set to discharge
to ensure the safety of the vessel?
A) Exactly 150 PSI.
B) Slightly above 150 PSI, but not to exceed the vessel's design limitations.
C) 200 PSI to allow for operational spikes during heavy tool usage.
D) 125 PSI to provide a safety buffer.
Correct Answer: B - Slightly above 150 PSI, but not to exceed the vessel's design limitations.
,Rationale: Safety valves are designed to prevent the pressure from exceeding the MAWP. Setting
it exactly at 150 PSI could cause nuisance tripping due to normal operating fluctuations, but
setting it too high (Option C) creates a significant explosion risk. Option D would cause the
valve to vent prematurely during normal operation.
Question 3: During a routine inspection, you observe that the pressure gauge needle is oscillating
rapidly. What is the most likely cause, and what action should be taken?
A) This is normal behavior for compressors; no action is required.
B) The compressor is undersized for the load; increase the RPM to compensate.
C) It indicates a potential issue with the dampening mechanism or pressure fluctuations; report it
for immediate inspection or repair.
D) The receiver tank is over-pressurized; bleed the tank manually.
Correct Answer: C - It indicates a potential issue with the dampening mechanism or
pressure fluctuations; report it for immediate inspection or repair.
Rationale: A rapidly oscillating needle (chatter) indicates either a mechanical issue with the
gauge or instability in the air line pressure. Ignoring this (Option A) is unsafe. Increasing RPM
(Option B) could cause mechanical failure, and bleeding the tank (Option D) does not address
the faulty instrumentation.
Question 4: Where must the A-35 Certificate of Fitness be kept during the operation of an air
compressor?
A) Secured in the central office safe.
B) Posted at the primary location where the air compressor is being operated or kept readily
available for inspection.
C) Kept in the operator's personal vehicle.
D) It only needs to be produced if an accident occurs.
Correct Answer: B - Posted at the primary location where the air compressor is being
operated or kept readily available for inspection.
Rationale: Regulatory compliance dictates that certificates of fitness must be readily available at
the site of operation to demonstrate the competence of the person currently in charge of the
equipment.
Question 5: What is the primary purpose of the condensate drain valve located at the bottom of
the air receiver tank?
, A) To maintain constant tank temperature.
B) To allow the compressor to cycle faster.
C) To remove accumulated water and oil to prevent corrosion and tank explosion.
D) To lubricate the internal walls of the receiver tank.
Correct Answer: C - To remove accumulated water and oil to prevent corrosion and tank
explosion.
Rationale: Compressed air contains moisture. If not drained, this moisture accumulates at the
bottom of the tank, causing internal corrosion (thinning the metal), which significantly weakens
the structural integrity of the pressure vessel.
Question 6: If an air compressor is being used in an area where flammable vapors may be
present, which of the following is a mandatory precaution?
A) The compressor must be fitted with an explosion-proof motor and specialized intake
filtration.
B) The compressor must be operated only at night.
C) The compressor should be kept running continuously to ensure air turnover.
D) No special precautions are needed if the compressor is outdoors.
Correct Answer: A - The compressor must be fitted with an explosion-proof motor and
specialized intake filtration.
Rationale: Standard electric motors can produce sparks during startup or operation, which can
ignite flammable vapors. Using standard equipment in a hazardous environment is a major
fire/explosion risk.
Question 7: A fusible plug is sometimes found on air compressor systems. What is its function?
A) To regulate the flow of compressed air to the distribution manifold.
B) To melt at a predetermined high temperature, releasing pressure if a fire occurs or the
compressor overheats.
C) To act as a secondary check valve for the oil lubrication system.
D) To measure the vibrations of the compressor head.
