Z-51 Written Test Newest 2025 Actual Exam

pg. 1 Z-51 Written Test Newest 2025 Actual Exam| Complete 150 Real Exam Questions and Correct Detailed Answers (Verified Answers) Already Graded A+|| New!!

How much extra refrigerant con be stored in a machine room?

• 330 lbs.
• The amount equal to the design pressure.
• 20% above normal charge.
• 220 lbs. - Correct Answer - 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

• temperature and pressure controls.
• refrigerant charge.
• cooling tower operation.
• liquid-line solenoid valve. - Correct Answer - A) temperature and

pressure controls.

The use of oil in the refrigeration machine is to

• Add non-condensates to refrigerant.
• Mix the oil with liquid refrigerant. 1 / 4

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• Reduce wear and friction in compressor parts.
• None of the answers are correct. - Correct Answer - C) Reduce wear

and friction in compressor parts.

The heat removed from the refrigerant condenser is

• latent heat only.
• sensible heat only.
• sensible and latent heat.
• Radiant heat only. - Correct Answer - C) sensible and latent heat.

Which service valve should be installed in a dual pressure release valve while keeping system in service?

• Two-way valve.
• Plug valve.
• Three-way valve.
• Stop valve. - Correct Answer - C) Three-way valve.

The monthly quick check of a fire extinguisher does NOT include

• Checking the extinguisher for damage.
• Confirming its proper location.
• Discharging the extinguisher.
• Ensuring it is clear from any obstructions. - Correct Answer - C)

Discharging the extinguisher.

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pg. 3 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 Q-01 refrigeration engineer holding S-12 CoF.
• A Master Fire Suppression Contractor holding S-12 CoF.
• Any Master Fire Suppression Piping Contractor.
• A S-12 CoF holder without any other license. - Correct Answer - B) A

Master Fire Suppression Contractor holding S-12 CoF.

A FDNY permit is required to conduct hot work for

• brazing.
• welding.
• use of oxygen and flammable gas.
• All answers are correct - Correct Answer - D) All answers are correct

Which of the following correctly describes the object in the picture below?

• Carbon dioxide system nozzle, to extinguish electrical fires.
• Cooling tower makeup valve, to put out fires in case of emergency.
• Standpipe hose outlet, to put out fires in case of emergency.
• Water chemistry supply station, for condenser water. - Correct

Answer - C) Standpipe hose outlet, to put out fires in case of emergency.

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pg. 4 While on duty, a refrigerant engineer notices that the suction line to the compressor and part of the compressor is frosted. Of the following, the most likely reason for this condition is

• the TEV is almost closed.
• overcharge.
• there is a blockage in the liquid line
• low condenser water temperature. - Correct Answer - B) overcharge.

You find that the check valve on a centrifugal pump is leaking. When will the most damage be caused to the pump?

• When another pump is turned on.
• On shutdown.
• When servicing the pump.
• On startup. - Correct Answer - D) On startup.

What is the lowest temperature the water in the cooling tower can be?

• Ambient.
• Between wet and dry bulb.
• Dry bulb.
• Wet bulb. - Correct Answer - B) Between wet and dry bulb.

The most important reason to subcool the refrigerant in the condenser is to ensure that

• liquid slugs will not enter the compressor.
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