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FDNY Z51 TEST EXAM ,Z51 WRITTEN TEST TAURIS
AND A STUDY GUIDE EXAM 2024 VERSION 200
QUESTIONS WITH DETAILED VERIFIED ANSWERS
AND RATIONALES /A+ GRADE ASSURED
In a steam turbine, what is the function of a Kingsbury thrust bearing? A) Maintain first stage steam pressure. B) Compensate for coupling misalignment. C) Adjust shaft torque at start up. D) Maintain axial positioning of the rotor shaft. - CORRECT ANSWER-D) Maintain axial positioning of the rotor shaft. Hot work authorizations are issued by A) a Responsible Person designated by the Building Owner. B) a Building Department inspector. C) a FDNY inspector. D) the Building owner's insurance company. - CORRECT ANSWER-A) a Responsible Person designated by the building owner. Insecticidal fogging operations are hazardous because chemicals A) are corrosive. B) are water-reactive. C) may be toxic. D) are highly unstable. - CORRECT ANSWER-C) may be toxic. What is a compressor safety head? A) Rupture disc. B) A pressure relief valve on the low side. C) Cylinder head with a low pressure relief on the high side. D) A spring on the valve plate. - CORRECT ANSWER-
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. - CORRECT ANSWER- Where is emergency power not required according to code? A) Fire pumps. B) High rise elevators. C) Egress illumination. D) Data centers. - CORRECT ANSWER-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. - CORRECT ANSWER- 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.
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. - 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 A) temperature and pressure controls. B) refrigerant charge. C) cooling tower operation. D) liquid-line solenoid valve. - CORRECT ANSWER-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. - CORRECT ANSWER-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. - CORRECT ANSWER-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. - CORRECT ANSWER-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. - CORRECT ANSWER-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. - CORRECT ANSWER-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 - CORRECT ANSWER-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. D) Water chemistry supply station, for condenser water. - CORRECT ANSWER-C) Standpipe hose outlet, to put out fires in case of emergency.
B) Air-limiting device. C) Heater coil. D) Resistor. - CORRECT ANSWER-B) Air-limiting device. An engineer observes a gauge that reads saturation pressure of a refrigerant. If chilled water is circulated as the cooling medium, this reading can best be used to estimate the A) chilled water return from building spaces being pumped to the spaces being cooled. B) cooling tower efficiency. C) pressure of chilled water being pumped to spaces being cooled. D) temperature of chilled water being pumped to the spaces being cooled. - CORRECT ANSWER-D) temperature of chilled water being pumped to the spaces being cooled. The purpose of wear rings in a centrifugal pump is to A) act as a bearing to reduce axial motion after wear occurs. B) prevent wearing of the pump housing and impeller. C) center the impeller in the pump casing. D) minimize water leakage around the shaft. - CORRECT ANSWER-B) prevent wearing of the pump housing and impeller. Of the follow, an example of an in-line refrigerant cleaning system that may be used with a centrifugal compressor containing R123 refrigerant is: A) Refrigerant reclaiming. B) Refrigerant disposal. C) Refrigerant recycling. D) Refrigerant recovery. - CORRECT ANSWER-C) Refrigerant recycling. Refrigerating system refrigerant detection systems must be tested at least
A) annually. B) monthly. C) daily. D) weekly. - CORRECT ANSWER-B) monthly. Capacitors are used on refrigeration motors. Of the following, the function of these devices is to A) store electrical charges during starting and running the motor. B) act as inductive devices to cause the motor current to lag the voltage. C) convert electrical to magnetic and then to mechanical energy. D) defrost refrigerant cooled motors. - CORRECT ANSWER-A) store electrical charges during starting and running the motor. Liquid refrigerant that has passed through a metering device is a A) high-pressure liquid. B) low-pressure saturated liquid. C) subcooled liquid. D) low-pressure vapor. - CORRECT ANSWER-B) low-pressure saturated liquid. Why are mirrors prohibited to be placed on exit doors? A) It will be difficult to keep the mirrors clean. B) The mirrors will cause major obstructions for the first responders. C) The mirrors will break easily. D) The mirrors will confuse the direction of exit. - CORRECT ANSWER-D) The mirrors will confuse the direction of exit.
Which of the following personnel is qualified to supervise the inspection, testing and maintenance of emergency power systems? A) A F-01 CoF holder. B) A S-95 CoF holder. C) A Q-01 CoF holder. D) Anyone who is designated by the building owner. - CORRECT ANSWER-C) A Q-01 CoF holder. The most important reason to use at least two compressors in a cascade system is to A) avoid the need for a water-cooled condenser. B) divide the cooling load between the compressors. C) accomplish higher temperature. D) avoid very high compression ratio for each compressor. - CORRECT ANSWER-D) avoid very high compression ratio for each compressor. Where must the Material Safety Data Sheets be located? A) Where any toxic material is used. B) Near the entrance to the machine room. C) Where flammable liquids are used. D) Where available to all employees. - CORRECT ANSWER-D) Where available to all employees. If a sprinkler system is offline for two days, how often do you need to inspect until it is returned to service? A) 12-hours a day until system is restored. B) Continuously, 24-hours a day until system is restored. C) Only in the evening, until restored.
D) Only in the morning, until restored. - CORRECT ANSWER-B) Continuously, 24-hours a day until system is restored. Where is the muffler located? A) After the condenser. B) Before the compressor. C) Between the evaporator and condenser. D) Between the compressor and condenser. - CORRECT ANSWER-D) Between the compressor and condenser. On an operating centrifugal compressor refrigerant unit, the refrigeration engineer notices that the compressor is short-cycling. The unit is using the low-side float valve as a metering device. Of the following requirements, this would indicate that A) the system is undercharged with refrigerant. B) the system is overcharged with refrigerant. C) an inspection should be made for a dirty and partially plugged discharge line. D) the compressor wiring should be inspected. - CORRECT ANSWER-A) the system is undercharged with refrigerant. What should be done to prevent accidental activation of smoke detectors during hot work operation? A) Place fire alarm system out of service, notify the Central Watch Station and provide fire watch. B) Remove the batteries from the smoke detectors. C) Cover the smoke detectors with plastic bags. D) Inform the Central Station to ignore any fire alarm signal during the hot work operation. - CORRECT ANSWER-A) Place fire alarm system out of service, notify the Central Watch Station and provide fire watch. Under normal conditions, the refrigerant enters the compressor as a
A chilled water system uses refrigerant R134a, a leak in the evaporator shell may result in A) higher than normal high-side pressure. B) a foam of ice around the point of the leak. C) low-pressure shutdown. D) set off the refrigerant monitor alarm. - CORRECT ANSWER-D) set off the refrigerant monitor alarm. The packing gland of a centrifugal pump serves to A) All of the answers are correct. B) keep the air out of the pumps when the impeller housing is under negative pressure. C) the drip part of the packing gland gives evidence that there is water in the pump. D) keep the bearing cooled. - CORRECT ANSWER-C) the drip part of the packing gland gives evidence that there is water in the pump. The installation of an inline refrigerant cleaning system is advisable A) to purge non-condensables. B) for high-pressure refrigerant systems. C) for systems using toxic refrigerant. D) to remove impurities from the system. - CORRECT ANSWER-D) to remove impurities from the system. A refrigeration engineer is running two centrifugal water pumps in parallel. One of the pumps is running at maximum pumping rate. If, by mistake, the refrigeration engineer throttles back on the discharge valve of the other pump, the most likely effect will be A) for the pump components to maintain both the flow rate and the discharge pressure. B) a reduction in the water pressure at the condenser inlet. C) a reduction on the total flow rate to the condenser.
D) a reduction in both the water flow rate and pressure to the condenser. - CORRECT ANSWER-C) a reduction on the total flow rate to the condenser. When entering Phase 2 fireman's service, which statement is correct? A) Can only be used by a firefighter. B) Must be tested semi-annually. C) Does not need a special key. D) The elevator operator is the only person that could control the elevator. - CORRECT ANSWER-D) The elevator operator is the only person that could control the elevator. In a building with a multizone standpipe system, how is each zone supplied water? A) It will supply only the highest standpipe zone. B) Each zone will have its own automatic water supply. C) Each zone will be connected to the main water supply. D) It will supply only the lowest standpipe zone. - CORRECT ANSWER-B) Each zone will have its own automatic water supply. The amount of electrical power used to operate a solenoid valve or motor is measured in A) amperes. B) ohms. C) foot pounds. D) volts. - CORRECT ANSWER-D) volts. The suction service valve of a reciprocating compressor is front-seated and the compressor runs until the low-pressure cut-out shuts the compressor off. When the machine is off, the refrigeration engineer notices that the suction pressure increases rapidly. The most probable cause of the pressure rise is
A) Place the thermometer in a cup of hot water. B) Place the thermometer in superheated steam. C) Place the thermometer in a cup of ice water. D) Compare temperature to another thermometer. - CORRECT ANSWER-C) Place the thermometer in a cup of ice water. An equalizer line on a TXV is used to A) Compensate for the pressure drop across the evaporator coil. B) Eliminate the pressure across the evaporator. C) Equalize the pressure across the TXV diaphragm or bellow. D) correct for pressure drop in the thermal bulb capillary lines. - CORRECT ANSWER-A) Compensate for the pressure drop across the evaporator coil. Transfer switches of the emergency power system must be tested semi-annually. Which is the correct statement regarding the testing procedure? A) Manually operate the switch from the standard position to the alternate position and then to return back to the standard position, B) Manually operate the switch from the standard position to the alternate position and leave it in the alternate position until the next test. C) Electrically operate the switch from the standard position to the alternate position and the return back to the standard position. D) Electrically operate the switch from the standard position to the alternate position and leave it in the alternate position until the next test. - CORRECT ANSWER-C) Electrically operate the switch from the standard position to the alternate position and the return back to the standard position. A __________ system is piping installed in a building that serves to transfer water to hose connections located within the building for firefighting purposes. A) sprinkler
B) standpipe C) hydrant D) water mist - CORRECT ANSWER-B) standpipe The cause of a starved evaporator might be A) low refrigerant charge. B) high refrigerant charge. C) superheat that is too low. D) high condenser water temperature. - CORRECT ANSWER-A) low refrigerant charge. When charging refrigerant on the low-pressure side of a reciprocating machine with manifold gauges, what is the position of the manifold? A) High-side and low-side front-seated. B) High-side, front-seated and low-side, back-seated. C) High-side, back-seated and low-side, front-seated. D) High and low back-seated. - CORRECT ANSWER-B) High-side, front-seated and low-side, back-seated. A reciprocating compressor cylinder has a 10-inch more and a 14-inch stroke. The volume of the refrigerant, in cubic inches, will be close to A) 1808 B) 1406 C) 1099 D) 1002 - CORRECT ANSWER-C) 1099 If R134a comes in contact with a refrigeration engineer's skin, what first aid should be applied from the MSDS?
When is a chemical fire extinguisher system needed? A) Where water is not sufficient. B) High-rise office buildings. C) Deluge systems. D) Pre-action systems. - CORRECT ANSWER-A) Where water is not sufficient. The standpipe certificate should be available for A) FDNY and OSHA. B) FDNY and Building Inspector. C) FDNY and EPA. D) FDNY and NFPA. - CORRECT ANSWER-B) FDNY and Building Inspector. As an engineer, you notice that the pressure drops across the evaporator. You check and notice the external equalized line is disconnected. What will occur in the evaporator? A) The evaporator will stabilize. B) The evaporator will flood. C) The evaporator will be unaffected. D) The evaporator will starve. - CORRECT ANSWER-B) The evaporator will flood. A water pump is discharging against head 92-feet of water. This is approximately to a pressure of A) 20 psi. B) 95 psi. C) 40 psi. D) 180 psi. - CORRECT ANSWER-C) 40 psi.
A refrigerant engineer verifies that a chilled water pump is cavitating. The most likely cause of this condition is A) too long a period between pump servicing. B) operating at sustained high loads. C) a faulty cooling tower water level controller. D) water leaking through mechanical seals. - CORRECT ANSWER-B) operating at sustained high loads. Capacity control of a reciprocating hermetic compressor is typically achieved through A) regulating the opening of the discharge valve. B) regulating the opening of the TXV. C) variation of the condenser water temperature. D) operation of the hot gas bypass valve. - CORRECT ANSWER-D) operation of the hot gas bypass valve. You are performing hot work near a sprinkler head. What can be done to prevent the fire alarm from going off? A) Drain the sprinkler system in that area. B) Use a noncombustible barrier to protect the sprinkler head. C) Perform hot work in service area. D) Take the building offline. - CORRECT ANSWER-B) Use a noncombustible barrier to protect the sprinkler head. Which of the following does not require flame resistant treatment? A) Decorations in a building lobby. B) Artwork in a museum. C) Decorations in a hotel lobby.
