Z-51 COMPREHENSIVE EXAM 2025/2026 QUESTIONS WITH
ANSWERS GRADED A+
✔✔The oil collected in an oil separator is generally
A) caused by an oil overcharge.
B) returned to the compressor.
C) filtered and returned to the compressor.
D) drained and replaced by fresh oil. - ✔✔
✔✔Where is emergency power not required according to code?
A) Fire pumps.
B) High rise elevators.
C) Egress illumination.
D) Data centers. - ✔✔D) Data centers.
✔✔Modern compressors usually seal the rotating shaft seal as it exits the compressor
housing a spring-loaded seal made of
A) low-friction plastic.
B) rubber.
C) metal or carbon.
D) graphite-loaded fiber. - ✔✔
✔✔A technician shows up to service the fire alarm panel in your building. What COF
qualifications must he/she have?
A) A Q-01/Q-99 Certificate of Qualification holder who is designated by the building
owner.
B) A certified Fire Safety Director who is designated by the building owner.
C) A S-95 Certificate of Fitness holder who is employed by a FDNY certified company.
D) A S-97/S-98 Certificate of Fitness holder who is employed by a FDNY certified
company. - ✔✔D) A S-97/S-98 Certificate of Fitness holder who is employed by a FDNY
certified company.
✔✔Which statement is correct regarding a fusible plug on a condenser?
A) The melting point is marked on it.
B) Are not allowed by code.
C) Release refrigerant by pressure.
D) Can be back-seated. - ✔✔
✔✔In an office building, the display of cut natural trees (Christmas trees) is
,A) never allowed.
B) allowed provided they are removed once they dry out.
C) always allowed.
D) allowed during the holiday season. - ✔✔A) never allowed.
✔✔Describe the equipment's function in the picture.
A) Control flow of refrigerant to the compressor.
B) Remove non-condensable from the condenser.
C) Relieve excess pressure from the condenser.
D) Relieve excess pressure from the evaporator. - ✔✔B) Remove non-condensable
from the condenser.
✔✔When the expansion valve is operating properly, the end of the evaporator will
contain
A) only superheated vapor.
B) saturated liquid refrigerant
C) only vapor.
D) only liquid refrigerant. - ✔✔A) only superheated vapor.
✔✔How much extra refrigerant con be stored in a machine room?
A) 330 lbs.
B) The amount equal to the design pressure.
C) 20% above normal charge.
D) 220 lbs. - ✔✔C) 20% above normal charge.
✔✔A refrigeration compressor has failed to turn on. The refrigeration engineer on duty
verifies that the electrical circuit to the motor, including all switches and circuit breakers,
is complete according to recommended service practice. The next item to be checked
would likely by the
A) temperature and pressure controls.
B) refrigerant charge.
C) cooling tower operation.
D) liquid-line solenoid valve. - ✔✔A) temperature and pressure controls.
✔✔The use of oil in the refrigeration machine is to
A) Add non-condensates to refrigerant.
B) Mix the oil with liquid refrigerant.
C) Reduce wear and friction in compressor parts.
D) None of the answers are correct. - ✔✔C) Reduce wear and friction in compressor
parts.
, ✔✔The heat removed from the refrigerant condenser is
A) latent heat only.
B) sensible heat only.
C) sensible and latent heat.
D) Radiant heat only. - ✔✔C) sensible and latent heat.
✔✔Which service valve should be installed in a dual pressure release valve while
keeping system in service?
A) Two-way valve.
B) Plug valve.
C) Three-way valve.
D) Stop valve. - ✔✔C) Three-way valve.
✔✔The monthly quick check of a fire extinguisher does NOT include
A) Checking the extinguisher for damage.
B) Confirming its proper location.
C) Discharging the extinguisher.
D) Ensuring it is clear from any obstructions. - ✔✔C) Discharging the extinguisher.
✔✔Several components of a sprinkler system in an office building need to be repaired.
Which of the following are allowed to perform the repair work?
A) A Q-01 refrigeration engineer holding S-12 CoF.
B) A Master Fire Suppression Contractor holding S-12 CoF.
C) Any Master Fire Suppression Piping Contractor.
D) A S-12 CoF holder without any other license. - ✔✔B) A Master Fire Suppression
Contractor holding S-12 CoF.
✔✔A FDNY permit is required to conduct hot work for
A) brazing.
B) welding.
C) use of oxygen and flammable gas.
D) All answers are correct - ✔✔D) All answers are correct
✔✔Which of the following correctly describes the object in the picture below?
A) Carbon dioxide system nozzle, to extinguish electrical fires.
B) Cooling tower makeup valve, to put out fires in case of emergency.
C) Standpipe hose outlet, to put out fires in case of emergency.
ANSWERS GRADED A+
✔✔The oil collected in an oil separator is generally
A) caused by an oil overcharge.
B) returned to the compressor.
C) filtered and returned to the compressor.
D) drained and replaced by fresh oil. - ✔✔
✔✔Where is emergency power not required according to code?
A) Fire pumps.
B) High rise elevators.
C) Egress illumination.
D) Data centers. - ✔✔D) Data centers.
✔✔Modern compressors usually seal the rotating shaft seal as it exits the compressor
housing a spring-loaded seal made of
A) low-friction plastic.
B) rubber.
C) metal or carbon.
D) graphite-loaded fiber. - ✔✔
✔✔A technician shows up to service the fire alarm panel in your building. What COF
qualifications must he/she have?
A) A Q-01/Q-99 Certificate of Qualification holder who is designated by the building
owner.
B) A certified Fire Safety Director who is designated by the building owner.
C) A S-95 Certificate of Fitness holder who is employed by a FDNY certified company.
D) A S-97/S-98 Certificate of Fitness holder who is employed by a FDNY certified
company. - ✔✔D) A S-97/S-98 Certificate of Fitness holder who is employed by a FDNY
certified company.
✔✔Which statement is correct regarding a fusible plug on a condenser?
A) The melting point is marked on it.
B) Are not allowed by code.
C) Release refrigerant by pressure.
D) Can be back-seated. - ✔✔
✔✔In an office building, the display of cut natural trees (Christmas trees) is
,A) never allowed.
B) allowed provided they are removed once they dry out.
C) always allowed.
D) allowed during the holiday season. - ✔✔A) never allowed.
✔✔Describe the equipment's function in the picture.
A) Control flow of refrigerant to the compressor.
B) Remove non-condensable from the condenser.
C) Relieve excess pressure from the condenser.
D) Relieve excess pressure from the evaporator. - ✔✔B) Remove non-condensable
from the condenser.
✔✔When the expansion valve is operating properly, the end of the evaporator will
contain
A) only superheated vapor.
B) saturated liquid refrigerant
C) only vapor.
D) only liquid refrigerant. - ✔✔A) only superheated vapor.
✔✔How much extra refrigerant con be stored in a machine room?
A) 330 lbs.
B) The amount equal to the design pressure.
C) 20% above normal charge.
D) 220 lbs. - ✔✔C) 20% above normal charge.
✔✔A refrigeration compressor has failed to turn on. The refrigeration engineer on duty
verifies that the electrical circuit to the motor, including all switches and circuit breakers,
is complete according to recommended service practice. The next item to be checked
would likely by the
A) temperature and pressure controls.
B) refrigerant charge.
C) cooling tower operation.
D) liquid-line solenoid valve. - ✔✔A) temperature and pressure controls.
✔✔The use of oil in the refrigeration machine is to
A) Add non-condensates to refrigerant.
B) Mix the oil with liquid refrigerant.
C) Reduce wear and friction in compressor parts.
D) None of the answers are correct. - ✔✔C) Reduce wear and friction in compressor
parts.
, ✔✔The heat removed from the refrigerant condenser is
A) latent heat only.
B) sensible heat only.
C) sensible and latent heat.
D) Radiant heat only. - ✔✔C) sensible and latent heat.
✔✔Which service valve should be installed in a dual pressure release valve while
keeping system in service?
A) Two-way valve.
B) Plug valve.
C) Three-way valve.
D) Stop valve. - ✔✔C) Three-way valve.
✔✔The monthly quick check of a fire extinguisher does NOT include
A) Checking the extinguisher for damage.
B) Confirming its proper location.
C) Discharging the extinguisher.
D) Ensuring it is clear from any obstructions. - ✔✔C) Discharging the extinguisher.
✔✔Several components of a sprinkler system in an office building need to be repaired.
Which of the following are allowed to perform the repair work?
A) A Q-01 refrigeration engineer holding S-12 CoF.
B) A Master Fire Suppression Contractor holding S-12 CoF.
C) Any Master Fire Suppression Piping Contractor.
D) A S-12 CoF holder without any other license. - ✔✔B) A Master Fire Suppression
Contractor holding S-12 CoF.
✔✔A FDNY permit is required to conduct hot work for
A) brazing.
B) welding.
C) use of oxygen and flammable gas.
D) All answers are correct - ✔✔D) All answers are correct
✔✔Which of the following correctly describes the object in the picture below?
A) Carbon dioxide system nozzle, to extinguish electrical fires.
B) Cooling tower makeup valve, to put out fires in case of emergency.
C) Standpipe hose outlet, to put out fires in case of emergency.
