Download FDNY Z51 Exam: Refrigeration Systems - 200+ Real Exam Questions with Verified Answers and more Quizzes Refrigeration and Air Conditioning in PDF only on Docsity!
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"The chilled water supply to the building is 55F. if the chiller is being used for human comfort, should you be concerned about this , and why? - CORRECT ANSWER=> Yes, this temperature is too high for human comfort purpose" "The packing gland of a centrifugal pump serves to: - CORRECT ANSWER=> The drip part of the packing gland gives evidence that there is water in the pump" "Capacity control of a reciprocating hermetic compressor is typically achieved through - CORRECT ANSWER=> Operation of the hot gas bypass valve" "The most important reason to sub-cool the refrigerant in the condenser is to ensure that: - CORRECT ANSWER=> A pure liquid refrigerant will enter the metering device" "A refrigeration engineer is logging reading from a reciprocating system. compressor discharge temperature have dropped significantly and the suction line pressure is high. which of the following that may be causing this set of condition. - CORRECT ANSWER=> An expansion valve that is open to wide" "A low side float valve is used to maintain: - CORRECT ANSWER=> The level of the refrigerant in the evaporator" "Regarding fire safety, which ASHARE refrigerant safety classification indicates no flammability and lower the toxicity? - CORRECT ANSWER=> A1" "When an expansion valve is operating properly, at the end of the evaporator will contain: - CORRECT ANSWER=> Only superheated vapor" "What information is not contained in a material safety data sheet-MSDS? - CORRECT ANSWER=> Cost of material"
"In a steam turbine, what is the function of the kingsbury thrust bearing - CORRECT ANSWER=> Maintain axial positioning of the rotor shaft" "A centrifugal water pump is considered to be fully primed when - CORRECT ANSWER=> The pump is full of liquid" "Copper tubing refrigerant lines must be installed for a new system. it is a well known service practice that tubing collapses at bends that must be made, the refrigerant engineer should use - CORRECT ANSWER=> Lever type tubing bender" "A reciprocating compressor is making a knocking sound during operation. if the refrigerant worn parts are not causing the knocking, what is probably the cause - CORRECT ANSWER=> The slugging of the liquid refrigerant" "In order for a refrigerant to become superheated in a section of the lowside refrigerant line: - CORRECT ANSWER=> Where no liquid refrigerant is present" "All liquid has been recovered from a system to be overhauled, the system - CORRECT ANSWER=> Should not be opened until all vapor has been removed" "When a refrigerant engineer uses a portable compressor recovery unit to remove vapor refrigerant from a refrigeration system the removal rate of the refrigerant will gradually slow down because - CORRECT ANSWER=> The vapor density is decreasing" "You are the engineer running a 2000-ton (steam-driven turbine) centrifugal refrigeration system, a refrigeration system supplies chilled water to a college campus with multiple buildings. During the course of making your rounds, you check the 9 cell cooling tower on the roof. You note the water level in all of the cooling tower cells is very low. Which one of the following immediate action would take? - CORRECT ANSWER=> Add additional make up water to cooling tower" "A rooftop water cooling tower is connected to a water pump in the building basement with a 12 inches diameter pipe. with the pump turn off, a pressure gauge at the pumps inlet show a pressure of 140 PSIG the height of the water column, in feet, would be closet to. - CORRECT ANSWER=> 323"
gallons of water do you expect to obtain if this pipe is drained completely? - CORRECT ANSWER=> 440" "A water chilling system uses refrigerant R123. a leak in the evaporator shell mat result in - CORRECT ANSWER=> A higher than normal high side pressure" "Capacitors are used on refrigeration motors. of the following, the function of these devices is to? - CORRECT ANSWER=> Store electrical charges during starting and running the motor" "Of the following, centrifugal refrigerant machine is best characterized by: - CORRECT ANSWER=> High volume low pressure machine" "Which of the following ASHRAE refrigerant safety classification is the most flammable? - CORRECT ANSWER=> A3" "Which of the following correctly describes the object in the picture below? - CORRECT ANSWER=> Standpipe hose outlet to put out fires in cae of emergency" "Modern compressors usually seal the rotating shaft as it exits the compressor housing a spring loaded seal made of - CORRECT ANSWER=> Metal or carbon" "The British Thermal Unit (BTU) is the measurement of heat of energy. if 10 BTU are transferred to 10 pounds of water, the water temperature increase will be closest to: - CORRECT ANSWER=> 1F" "A reciprocating compressor cylinder has a 10 inch bore and 14 inches stroke. the volume of refrigerant, in a cubic inches, will be closer to: - CORRECT ANSWER=> 1099" "An electrically operated control requires 24 volts to operate. to change the available 110 volts to 24 volts - CORRECT ANSWER=> Transformer" "In an indirect refrigerant system, of the following , the one that would not be used as a cooling medium for the building spaces being cooled is: - CORRECT ANSWER=> R22 refrigerant" "On a steam turbine, what would cause the atmospheric valve to open? - CORRECT ANSWER=> low vacuum in the surface condenser, leaking tubes in the surface condenser, dirty tubes n the surface condenser"
"You are the engineer running a 2000-ton (steam-driven turbine) centrifugal refrigeration system, a refrigeration system supplies chilled water to a college campus with multiple buildings. making your rounds, you notice that condenser water pump #1 is making a lot of noise, the discharger gauge reading of the condenser water pump is fluctuating drastically, and motor of the condenser pump #1 is running very hot. which of the following actions would you take: - CORRECT ANSWER=> Turn on pump #2 shut off pump #1, and trouble shot pump #1" "Electric devices may be used to provide built in defrosting of refrigeration machine evaporator units. these devices are classified as - CORRECT ANSWER=> Resistors" "The flash point of compressor lubricating oil: - CORRECT ANSWER=> Should be higher than the compression temperature" "The primary way of achieving capacity control of a centrifugal compressor is by; - CORRECT ANSWER=> Adjustment of the impeller inlet pre-rotation vanes" "Cooling tower water requires the addition of chemical additives in order to: - CORRECT ANSWER=> Reduce the formation of scale and algae" "In the picture below describe the equipment's function? - CORRECT ANSWER=> Remove non condensable from the condenser" "the viscosity of lubrication oil is described by a number. a low viscosity number describes oil that: - CORRECT ANSWER=> Flows easily" "The most likely reason for a refrigeration engineer to use a psychrometer is to measure - CORRECT ANSWER=> Relative humidity level of the atmosphere" "The most important reason to use at least two compressors in a cascade system is to: - CORRECT ANSWER=> Avoid very high compression ratio for each compressor" "The suction service valve of a reciprocating compressor is front seated and the compressor runs until the low pressure cut-out shut the compressor off. when the machine is stopped, the refrigeration engineer notices that the suction pressure increase rapidly. the most probable cause of this pressure rise: - CORRECT ANSWER=> Malfunction of a compressor valve" "Regarding the functioning of a steam turbine, why is it advisable to keep moisture in the inlet low as possible? - CORRECT ANSWER=> Keeps turbine blades wear to minimum"
"A refrigeration system uses jet ejector to raise settled oil mixed with refrigerant to the oil pump if a restriction in the refrigerant flow to the jet ejector develops: - CORRECT ANSWER=> There may be insufficient head to lift the oil" "An indirect ow temperature refrigerant system frequently uses glycol , instead of salt brine, as the intermediate cooling medium. an advantage of this choice is: - CORRECT ANSWER=> The elimination of corrosion" "In relation to the suction pressure of a compressor, the reading on the oil pressure gauge should read in the range, closer to: - CORRECT ANSWER=> 15 to 30 PSI Higher" "Non- condensable gases like air, oil vapor, or nitrogen travel through a refrigerant system with the refrigerant they usually accumulate in the: - CORRECT ANSWER=> Condenser" "The advantage of forced draft cooling tower over natural draft cooling tower is: - CORRECT ANSWER=> Smaller tower size" "The sole refrigeration engineer on duty in a building is permitted to leave the building refrigeration system when it is in operation when: - CORRECT ANSWER=> Relieved by another licensed refrigeration engineer" "A system controlled by a TXV show high discharge pressure and high normal sub-cooling. the cause is most probably a : - CORRECT ANSWER=> Refrigerant overcharge" "Which of the following is a correct statement? - CORRECT ANSWER=> 2.5 gallons of water weighs 20.8 pounds" "Liquid level gauge glasses (except the bull's eye) are generally equipped with: - CORRECT ANSWER=> Automatic shut-off valves only" "Copper and aluminum are frequently used for condenser tubes in refrigeration system. these metals are used because of their: - CORRECT ANSWER=> High heat transfer coefficient" "Assume that a refrigeration engineer has a choice of four valves to select from. which of the following is the most effective type of valve to control pressure? - CORRECT ANSWER=> Plug valve"
"Where must the material safety data sheet be located? - CORRECT ANSWER=> Where available to all employees" "The oil collected in an oil separator is generally: - CORRECT ANSWER=> Returned to the compressor" "What is the function of the gland steam? - CORRECT ANSWER=> Seal the turbine rotor carbon rings" "Regarding the functioning of steam turbine, how is the water level controlled in the surface condenser hot well? - CORRECT ANSWER=> Operation of the recirculation and overboard valves" "The cause of a starved evaporator might be: - CORRECT ANSWER=> Low refrigerant charge" "A refrigeration engineer is running two centrifugal condenser water pumps in parallel. one of the pumps is a 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: - CORRECT ANSWER=> A reduction on the total flow rate to the condenser" "The total amount of heat to be removed from the refrigerant in a condenser equals the heat picked up in the: - CORRECT ANSWER=> Evaporator plus the heat of compression" "The amount of electrical power used to operate a solenoid valve or a motor is measured in: - CORRECT ANSWER=> Volts" "Of the following, the most common metering device used today in reciprocating commercial refrigeration system under three tons capacity is: - CORRECT ANSWER=> TEV" "The purpose of wear rings in a centrifugal pump is to: - CORRECT ANSWER=> Prevent wearing of the pump housing and impeller" "You are the engineer running a 2000-ton (steam-driven turbine) centrifugal refrigeration system, a refrigeration system supplies chilled water to a college campus with multiple buildings. while making rounds, you notice that the condenser water coming back down from the 9-cell cooling tower on the roof is at a temperature of 90F. you want to make a adjustment to bring the temperature of the condenser water down to 85F. which of the following immediate actions would you take? - CORRECT ANSWER=> Increase the speed of the cooling tower fans"
"What are steam ejector used for on the surface condenser of a system with a turbine: - CORRECT ANSWER=> To create a proper opening exhaust system" "Water and moisture is serious problem in a refrigerant system how to avoid: - CORRECT ANSWER=> Proper evacuation at the charging of the system" "The most important requirements for a good evaporator is that: - CORRECT ANSWER=> It must have enough cooling surface to absorb the required heat" "While on duty a refrigeration engineer notice that the suction line to the compressor and part of the compressor itself is frosted of the following, the most likely reason for this condition would be: - CORRECT ANSWER=> There is not enough refrigerant in the system" "While doing a routine line inspection, the engineer notices the bulb of the TXV on the floor refrigerant engineer should attach bulb at the : - CORRECT ANSWER=> The outlet end of the coil" "To convert water 32F to ice at the same temperature a refrigeration system must remove: - CORRECT ANSWER=> The latent heat of fusion" "The use of oil in the refrigeration machine is to: - CORRECT ANSWER=> Reduce wear and friction in the compressor parts" "The following is a desirable property in a refrigeration - CORRECT ANSWER=> High latent heat" "The cooling medium for an evaporative condenser is: - CORRECT ANSWER=> Air and water" "The ratio of the actual pressure of water vapor in the atmosphere to the saturated pressure of give temperature is: - CORRECT ANSWER=> Relative humidity" "The only refrigerant/ temperature chart available to a refrigerant engineer list the temperature is degrees Celsius if the chart indicates a Celsius temperature of 4 degrees to equivalent to F: - CORRECT ANSWER=> 39.2 degrees" "A refrigerant engineers was instructed to charge of 60 ton plant with R134A refrigerant. the refrigerant engineer will most likely find the charging valve on the - CORRECT ANSWER=> Low pressure side of the system"
"A refrigerant engineer verifies that a chilled water pump is cavitating. of the following the most likely cause for this condition is: - CORRECT ANSWER=> Water leaks through the mechanical seals" "There is a decrease in the efficiency of a reciprocating compressor. this most likely caused by: - CORRECT ANSWER=> Leaking suction valve" "The suction and discharge valve of the reciprocating compressor are mounted as follows: - CORRECT ANSWER=> Discharge valves on top of the valve plate and suction valve below" "You are the engineer running a 2000-ton (steam-driven turbine) centrifugal refrigeration system, a refrigeration system supplies chilled water to a college campus with multiple buildings. while making your rounds you notice that the discharge pressure of your condenser water pumps is significantly lower than normal. which of the following action would you avoid taking: - CORRECT ANSWER=> Put on an additional surface condenser pump and lower the chilled water set point" "A water pump is discharge against head 92 feet of water, this is approximately to a pressure of:
- CORRECT ANSWER=> 40 psi" "Which of the following will connect to the middle port on a gauge manifold? - CORRECT ANSWER=> Vacuum pump" "The most important reason for installing a muffler in a reciprocating refrigerant machine is: - CORRECT ANSWER=> To contain the compressor pulsation noise" "Of the following, the statement that most accurately characterize a hermetic compressor is that it: - CORRECT ANSWER=> Will have both the compressor and motor enclosed is gas tight housing" "In the picture the valve is in what position (45 degree angle to the left) - CORRECT ANSWER=> The valve is crack open" "What is the order of components on the liquid line of a reciprocating system from the condenser to the TEV? - CORRECT ANSWER=> King valve, filter drier, solenoid valve, sight glass" "A high-side float valve is used to maintain: - CORRECT ANSWER=> Constant level of refrigerant in the evaporator"
"What is the advantage of a shell and tube condenser, as opposed to a shell and coil condenser?
- CORRECT ANSWER=> Better heat transfer" "Fusible plugs on a condenser: - CORRECT ANSWER=> The melting point is marked on it" "How much extra refrigerant can be stored in a machine room? - CORRECT ANSWER=> 330 lbs." "What is used on an outside pipe to prevent it from freezing? - CORRECT ANSWER=> Resistor" "Of the following centrifugal chillers are best characterized as? - CORRECT ANSWER=> High tonnage, low pressure machines" "As an engineer you notice pressure drops across the evaporator. you check and notice the external equalizer line is disconnected. what will occur in the evaporator? - CORRECT ANSWER=> Evaporator will flood" "When entering phase 2 fireman's service, what statement is correct? - CORRECT ANSWER=> The elevator operator is the only person that could control the elevator" "A FDNY permit is required to conduct hot works for? - CORRECT ANSWER=> Use of oxygen and flammable gas" "FDNY is most concerned with which ASHRAE refrigerant classification? - CORRECT ANSWER=> A3" "How long must a fire alarm log book be kept? - CORRECT ANSWER=> 3 years" "What is the minimum requirement an engineer needs to log readings? - CORRECT ANSWER=> Once per shift" "You are the only engineer on duty with a machine running. a vice president tells you to shovel snow. what should you do? - CORRECT ANSWER=> Do not leave the building" "How often must you do an emergency power testing? - CORRECT ANSWER=> Monthly" "What is the responsibility of a B29 COF holder? - CORRECT ANSWER=> Inspect the battery system"
"Why is refrigerant gauge called a compound gauge? - CORRECT ANSWER=> It reads positive pressure and vacuum" "Which of the following does not require flame resistant treatment? - CORRECT ANSWER=> ART work in a museum" "An engineer observes a gauge that reads saturation pressure of a refrigerant. if chilled water s circulate as the cooling medium this reading best be used to estimate the? - CORRECT ANSWER=> Temperature of chilled water being pumped to the space being cooled" "Regardless of the ASHRAE refrigerant classification in use, in the event of a refrigerant escape the engineer should be aware of? - CORRECT ANSWER=> Asphyxiation" "What type of refrigerant is found inside the machines Gauges? - CORRECT ANSWER=> Same type of refrigerant inside the machine" "If resistance is cut in half, what happens to the power factor? - CORRECT ANSWER=> Increases by a factor of two" "What are pre hot works procedures performed prior to hot works? - CORRECT ANSWER=> Check area once a day leading up to hot works" "A chilled water system has an air cooled condensing unit on a roof during cold weather ha what type of protection? - CORRECT ANSWER=> Air limiting device" "What is a compressor safety head? - CORRECT ANSWER=> A spring on the valve plate" "Stand pipe certificate should be available for? - CORRECT ANSWER=> FDNY and building inspector" "When is a chemical fire extinguisher system needed? - CORRECT ANSWER=> Where water is not sufficient" "What is most accurate about fire alarm books? - CORRECT ANSWER=> Must be kept in the fire alarm panel" "What is the volume of a box 12" x12" x12" measure? - CORRECT ANSWER=> 1 cubic foot"
"What does a wiring diagram display? - CORRECT ANSWER=> Wiring of components" "Filter driers remove - CORRECT ANSWER=> Moisture and particles" "Show a picture of an insulated pump and ask what is this pump? - CORRECT ANSWER=> Centrifugal chill water pump" "IF 29.92'HG is equal to 14.7 Psia then 26"HG converts to what in Psia? - CORRECT ANSWER=> 12.77" "When charging refrigerant on the low side of a reciprocating machine with manifold gauges, what is the position of the manifold? - CORRECT ANSWER=> High side frontseated low side backseated" "You are the engineer running a 2000 ton steam-driven turbine centrifugal refrigeration system, a refrigeration system supplies chilled water to a college campus with multiple buildings. you are supplying 46 degree chilled water. all the buildings are satisfied except one building. what action should the engineer do? - CORRECT ANSWER=> Put an additional chilled water pump online" "The cooling medium for a cooling tower is? - CORRECT ANSWER=> Air" "The charge in a TEV sensing bulb is? - CORRECT ANSWER=> Similar to refrigerant in system" "When you finished leak testing with R22 and nitrogen the next step should be? - CORRECT ANSWER=> Vent refrigerant and nitrogen to open air" "What is the device used to measure the speed of a turbine? - CORRECT ANSWER=> Tachometer" "The condenser pump is on the first floor and not running. the pressure gauge shows 55 psi. there is 15 feet for each floor. what floor is the cooling tower on? - CORRECT ANSWER=> 8" "There is 7.48 gallons per cubic foot. how many gallons of water are in a pipe 8 feet in diameter and 10 feet long? - CORRECT ANSWER=> 3758" "A technician had been asked to estimate the cost of operating a 5 horse power motor. because the plant is build by energy consumed as kiliowatt-hours, the technician will have to calculate
the conversion. the equivalent in energy of a 5 horse power motor operating for 9 hours in kiliowatt-hours is closest to: - CORRECT ANSWER=> 33.6" "A standpipe system will be out of service for two days. how long should there be a fire watch? - CORRECT ANSWER=> The entire time the standpipe is out of service" "A circuit breaker has a similar function as what? - CORRECT ANSWER=> A fuse" "How do you start a centrifugal chiller? - CORRECT ANSWER=> Start the chilled water pump, start the condenser water pump, check oil, start cooling tower, start compressor" "If a sprinkler system is offline for two days how often do you need to inspect it until it is returned back to service? - CORRECT ANSWER=> Continuously 24 hours a day until system is restored" "The only refrigerant/temperature chart available to a refrigerant engineer lists the temperature in degrees Celsius. if the chart indicates a Celsius temperature of 5 degrees the equivalent in Fahrenheit is? - CORRECT ANSWER=> 41 degrees" "In the picture below what does the equipment detect? - CORRECT ANSWER=> Refrigerant leaks" "In building with a multizone standpipe system, how does each zone get supplied with water? - CORRECT ANSWER=> Each zone will have its own automatic water supply" "Which service valve should be installed to isolate a dual pressure relief valve while keeping system in service? - CORRECT ANSWER=> Three way valve" "When will the BTU's exchanged be the greatest? - CORRECT ANSWER=> low evaporator temperature, high condenser temperature" "You find that the check valve on a centrifugal pump is leaking. when would the most damage be caused to the the pump? - CORRECT ANSWER=> On startup of the pump" "A motor winding is touching the inside of the motor housing. this could result in: - CORRECT ANSWER=> Shock may occur to personnel"
"What happens when a steam turbine reaches critical speed? - CORRECT ANSWER=> Turbine will vibrate violently" “The efficiency of the refrigerant cycle is affected by the operation of the condenser. of the following. a more efficient centrifugal compressor operation results from: - CORRECT ANSWER=> Lowering the condensing pressure" "The heat removed from the refrigerant in a condenser is: - CORRECT ANSWER=> Sensible and latent heat" "The refrigerant unit that you have been assigned to is being taken out of service for a major repair. you have been assigned to withdraw refrigerant for storage in suitable containers. according to the new York city fire code, you must ensure that the containers: - CORRECT ANSWER=> Are approved by the US department of transportation" "Which of the following best describes how the cylinder unloader work? - CORRECT ANSWER=> Keep in the suction valve opened while the compressor is in the return stroke" "In most semi hermetic compressors, the suction vapor is used to: - CORRECT ANSWER=> Cool the motor" "The amount of refrigerant that flows through the orifices of a economizer is determined by the: - CORRECT ANSWER=> Difference between the high side and load side pressure" "The installation of an inline refrigerant cleaning system is advisable: - CORRECT ANSWER=> To remove impurities from the system" "The type of refrigerant system that is least likely to leak refrigerant into the building space that are cooled - CORRECT ANSWER=> The indirect system" "The suction pressure of a reciprocating compressor is 65PSIG. the discharge pressure of this compressor is 120PSIG. the atmospheric is 14.7 PSI. the compression ratio for the given condition is closet to: - CORRECT ANSWER=> 1.69" "A super heated vapor is a? - CORRECT ANSWER=> Dry vapor above the saturation temperature"
"A refrigerant engineer verifies that a condenser water pump is cavitating. of the following the most likely cause for this condition is: - CORRECT ANSWER=> A faulty cooling tower water level controller" "A centrifugal water pump is known as a lift pump when the: - CORRECT ANSWER=> The water supply to the pump suction inlet is below the pump level" "A TXV is used to maintain constant: - CORRECT ANSWER=> Evaporator superheat"
