FDNY Operating Engineer Practice Test

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• How does a screw compressor generate pressure?
• What can be said about the operating pressures of Ammonia compared to Freon 12?
• What is the specific heat of water in BTUs per degree?
• When is a scale trap most effective in a compression refrigeration system?
• What type of metering device is commonly used in modern centrifugal chillers?
• What effect does a partially blocked orifice have on a thermostatic expansion valve?
• Which refrigerant state is associated with the evaporator inlet condition?
• Which characteristic of the evaporator's first coil section indicates it is absorbing sensible heat?
• Which type of compressor typically has the smallest displacement for a given operating condition?
• If the ball float in a high side float meter is punctured, what will happen to the evaporator?
• In a reciprocating refrigeration system with an evaporative condenser, where should the muffler be installed?
• What common characteristic do Freon-12 and methyl chloride share?
• Which condition indicates the efficiency of the evaporator in a refrigeration system?
• How does shortening the length of a capillary tube affect the refrigeration unit's operation?
• In a double pipe condenser, where is the refrigerant located?
• What are the three methods of heat transfer?
• What is the result of converting 115 degrees Centigrade to degrees Fahrenheit?
• What is the function of the suction valve in a compressor?
• Which of the following is needed to change the state of a substance?
• As the operating pressure of a refrigerant decreases, what happens to its volume?
• When should the finned coils of an evaporator be considered to be functioning efficiently?
• What is the consequence of blocked swirls in a vertical shell and tube condenser?
• What does the number 744 designate in refrigerants?
• In a shell and tube type evaporator, where is the refrigerant contained?
• Which calculation would convert 26 PSIA to PSIG?
• Which of the following best describes the operational characteristics of a centrifugal refrigeration machine?
• Which of the following cannot be used as a desiccant in a refrigerating system?
• In a flooded evaporator with a low side float, what factor determines the operation of the float mechanism?
• What will be the state of the refrigerant at the outlet of an evaporator with a saturation temperature of -10 deg F?
• At what temperature should a silica gel dryer be heated to reactivate it?
• What is the primary role of an evaporator in a refrigeration system?
• Which factor does not change when heat is added or removed during a phase change?
• What color will red litmus paper turn if NH3 is present?
• What does 1 Ton of Refrigeration equal in BTUs per minute?
• How does a liquid-moisture indicator reveal the presence of moisture?
• What effect does a clogged pleated media filter have on an evaporator system?
• Which dye is used to detect leaks in refrigerants?
• What process allows refrigerant to absorb additional heat energy as it passes through the compressor?
• What effect does a high-pressure drop in a refrigeration system typically have?
• What term describes the process of reducing the refrigerant volume to increase pressure?
• What is a key characteristic of the refrigerant in a shell and tube system?
• Which of the following best describes the characteristics of R-22?
• How does the specific heat of water change with temperature?
• Which metering device is designed specifically to maintain a constant superheat level?
• Which component can be removed without impacting the refrigeration process?
• What typical effect would charging an R-12 system with R-22 have on the compressor?
• What can an RMO estimate from the saturation pressure reading at an evaporator?
• What is the state of the refrigerant at the leaving side of the metering device?
• Which of the following names corresponds with the law that states the total pressure of a combined mixture of gases is the sum of the pressures of each constituent gas?
• Which best describes the internal structure of a shell and tube type evaporator?
• In refrigeration systems, what occurs to refrigerant after it completely changes into the liquid state?
• Which of the following arranges refrigeration components in the correct order?
• What happens to refrigerant as it passes through the evaporator coil?
• Which component is likely to cause issues if there is excessive condensation in the evaporator?
• What type of readings does a vacuum gauge display?
• Which instrument detects leaks by measuring the change in the resistance of a refrigerant vapor?
• Which component is responsible for stopping refrigerant flow in a refrigeration system?
• If a barometer shows a pressure reading of 29.40" Hg, what will it read when it increases to 34.4" Hg in pounds absolute?
• In a refrigeration system, what does the failure of the equalizer line generally indicate?
• What occurs if the equalizer line in a float chamber becomes obstructed?
• Which device is best suited for measuring a deep vacuum between 29.25" Hg and 29.92" Hg?
• What is the capacity of a refrigeration system that absorbs 800 BTUs per minute?
• Which voltage is typically used to operate an electric expansion valve in a refrigeration system?
• What is specific heat defined as?
• What will cause the flame of a halide torch to turn yellow?
• Which statement best describes a vertical shell and tube condenser?
• In the context of indirect refrigeration systems, what is one of the main concerns they address?
• When latent heat is added or removed from a substance, which of the following remains constant?
• What is the typical temperature of the chilled water supplied by an R22 system?
• Of the following pressures, which expresses the greatest value?
• How much water is typically conserved by replacing a shell and coil condenser with an evaporative condenser?
• Having a refrigeration system with three stages implies what about the refrigerant pressure?
• Which refrigerant is commonly used in residential air conditioning systems?
• What is the primary function of an accumulator in a refrigeration system?
• What process is required to change water at 32 degrees F into ice at 32 degrees F?
• A two cylinder single acting vertical compressor has a suction pressure of 45 PSIG. The purpose of the shaft seal is to keep:
• At 86 degrees Fahrenheit, what is the discharge pressure of R-744?
• How many baffles are typically present in a 3-pass horizontal shell and tube condenser?
• Which law describes the relationship observed when a gas is maintained at a constant pressure while its volume varies in direct proportion to the change in absolute temperature?
• If the temperature of 10 pounds of water is increased by 10 BTUs, how much does the temperature increase?
• For one pound of water at 32 degrees Fahrenheit, how many BTUs must be removed to create ice at 17 degrees?
• What type of component is designed to smooth pulsations of high-pressure vapor in a refrigeration system?
• What is the function of eliminators in a shell and tube type evaporator?
• What is one of the disadvantages of using Carbon Dioxide as a refrigerant?
• What is the temperature of water leaving a horizontal shell and tube condenser relative to the discharge gas?
• What determines the pressure developed by a centrifugal compressor?
• Which property is critical for a refrigerant to avoid failure in high pressure systems?
• What aspect of a rotary compressor contributes to its quieter operation compared to other compressors?
• What method is used to find leaks in a low-pressure chiller?
• Which component helps to minimize fluid loss in modern compressors?
• How can a shell and tube condenser compared to a shell and coil condenser be effectively maintained?
• Which of the following refrigerants has the designation R-40?
• What effect do fins have on a DX coil?
• What does the term "gauge pressure" specifically refer to?
• Which of the following units of pressure are considered absolute values?
• In a spray pond condenser, what chemical is commonly used to eliminate algae?
• Why must refrigerant be superheated before entering the compressor?
• Which refrigerant is known to sublimate?
• What type of condenser utilizes swirls to enhance water circulation?
• What can occur if a high side float is not functioning properly?
• How many BTUs per minute is equivalent to one ton of refrigeration?
• What does the crankcase pressure of an operating reciprocating compressor approximate?
• Which component helps prevent moisture and impurities from entering the refrigeration system?
• Which refrigerant is designated as R-718?
• If 1 BTU is added to 1 pound of water, what is the resultant temperature increase in degrees Fahrenheit?
• What is a primary function of baffles in a shell and tube condenser?
• Which of the following compressors uses non-positive (variable) displacement to increase the pressure of a refrigerant?
• Which device regulates refrigerant flow based on the needs of the evaporator?
• In a two-stage centrifugal compressor with an economizer, which stage holds the largest volume of vapor?
• What is the latent heat of fusion for water in BTUs?
• Which instrument is used to measure sensible heat?
• How many BTUs are required to vaporize one pound of water?
• Which form of heat transfer requires physical contact?
• How is heat transferred from air to the refrigerant in an evaporator?
• Why is it important for refrigerant entering the compressor to be 100% dry vapor?
• Which metering devices are designed without any adjustable features?
• A compound gauge reading of 10 inches of mercury (Hg) is equivalent to how many pounds absolute?
• If an automatic expansion valve is used in a variable load system, what is a likely outcome during high load conditions?
• At what pressure does water boil at 212 degrees Fahrenheit?
• Where is the most effective location for a refrigeration muffler to be installed?
• What is the main drawback of using soap and water for leak detection?
• What happens when there is an undercharge of refrigerant in a system using a thermostatic expansion valve?
• Which condenser type is known for requiring less water circulated compared to conventional systems?
• What design feature characterizes a screw compressor?
• What advantage do semi-hermetic compressors have compared to hermetic compressors?
• In addition to monitoring operating pressures, what task does the gauge manifold assist in?
• Which of the following refrigerants has a higher operating pressure at the same temperature compared to R-12?
• Which of the following sequences properly arranges liquid line components?
• What type of refrigeration system is likely to leak refrigerant into occupied spaces?
• Which cleaning solution is recommended for scale deposits in a shell and coil condenser?
• What is the best method for detecting leaks in a CO2 system?
• Where is the metering device's orifice typically located within a refrigeration system?
• Convert one PSI to the corresponding pressure in kilopascal (kPa):
• Which thermal property is considered undesirable for a refrigerant?
• What is -34 degrees Centigrade in degrees Fahrenheit?
• How does a correctly operating evaporator coil contribute to air conditioning?
• What pressure value is not equivalent to atmospheric pressure?
• How can you convert a measurement of 10 PSIG to PSIA?
• Which feature is characteristic of a manual metering device compared to a globe valve?
• What measurement unit is indicated for vacuum on a compound gauge?
• What is one of the primary concerns when maintaining refrigerant levels in an HVAC system?
• What is responsible for regulating the flow of refrigerant through an orifice plate?
• What is the function of eliminators within an evaporative condenser?
• What is the purpose of insulating the suction line of a compression system?
• Convert the vacuum pressure of 28" Hg to the corresponding absolute pressure:
• Which of the following pressure values does not indicate a perfect vacuum?
• What defines the cooling method of an evaporative condenser?
• Which of the following best describes how a "positive displacement" compressor increases the pressure of a refrigerant?
• Which of the following statements about a horizontal shell and tube condenser is true?
• In which type of compressor are both the motor and compressor enclosed within a welded housing?
• If the high side float in a refrigeration system fails to rise due to a puncture, what system operation is affected?
• In terms of leak detection, how is a soap and water solution applied?
• What temperature condition should the refrigerant maintain inside the evaporator?
• What effect will moving to a higher elevation have on barometric readings?
• What is one of the main uses of a hermetic compressor?
• Why is it essential to run the suction and liquid lines in physical contact with one another?
• Which device is commonly utilized to filter out moisture in a refrigeration system?
• If ammonia has leaked into the brine, what color will Nessler's solution turn?
• Aside from regulating refrigerant flow, what other function does a metering device perform?
• What is the purpose of using a heat exchanger between the liquid and suction lines?
• What type of compressor is typically used in systems operating under vacuum conditions?
• What is the state of the refrigerant as it enters and exits a condenser?
• How does the temperature of condenser water affect the rate of heat transfer?
• What force, alongside evaporator pressure, influences the operation of an automatic expansion valve?
• Which type of condenser can operate without water in winter conditions?
• What type of gauge should be used when a system's operating pressure will not exceed atmospheric pressure?
• What condition can cause frost to form on the top of a coil while the bottom remains dry?
• What is the main distinction between a water-cooled and air-cooled condenser?
• What is a common characteristic of orifice plates in refrigeration systems?
• When using a halide torch, what color will the flame turn when it detects a Freon leak?
• What could be the consequence of an expansion valve allowing excess refrigerant into a DX coil?
• What is the method to determine if a thermometer is indicating temperature accurately?
• What is one primary function of a compressor in a refrigeration system?
• In comparing air-cooled and water-cooled refrigeration systems, which statement is true regarding head pressure?
• What condition can occur if a suction line is not insulated?
• What factor influences the effectiveness of sub-cooling in a refrigeration system?
• R-22 is predominantly classified as which type of refrigerant?
• If the ball float of a low side float metering device sinks, what will happen to the suction pressure?
• When is frost formation likely to occur on evaporator coils?
• Convert a barometric pressure of 28" Hg to the corresponding absolute pressure:
• What is the purpose of installing a filter drier in the liquid line?
• What is true about the operation of a spray pond and evaporative condenser?
• Where is the water box located on a vertical shell and tube condenser?
• Which processor is utilized in high-pressure refrigerant leak tests?
• What is the correct formula for converting barometric pressure to PSIA?
• If an R-12 system is mistakenly charged with R-22, what effect could this have?
• When is a condenser most efficient at heat transfer?
• What type of compressor valves need the most clearance space when used on vertical compressors?
• What color change indicates the presence of CO2 when using Bromothymol blue?
• How does an evaporator primarily absorb heat from air or water?
• What type of process is done when vapor condenses into liquid?
• Which metering device requires the refrigeration system to be maintained at a critical charge?
• What best describes the temperature of a sub-cooled refrigerant?
• Which type of compressor uses rollers to compress refrigerant?
• What is the primary purpose of a Halide torch?
• Which of the following best describes the specific heat of water?
• What is the main purpose of baffles in the cooling coil of a direct expansion system?
• Where does the low-pressure side of a compression refrigeration system start and end?
• What is the state of the refrigerant when it enters and exits the compressor?
• How do you convert 87 degrees Fahrenheit into degrees Centigrade?
• What would be the heat transfer rate of a 30 ton refrigeration system?
• What does a compound gauge measure?
• What is the metric equivalent of barometric pressure expressed in millimeters of mercury for atmospheric pressure (29.92 "Hg)?
• What does loss of the liquid seal indicate in a refrigeration system?
• In a two-stage centrifugal compressor with an economizer, in which stage is the refrigerant pressure greatest?
• Which of the following best describes the state of the refrigerant at the inlet and outlet of the compressor?
• What type of heat is rejected from a condenser?
• Modern compressors use what type of material at their shaft seals?
• What is the primary function of a high side float in a refrigeration system?
• The performance of which component is indicated by the amount of sub-cooling in a refrigeration system?
• How much heat must be removed from water at 32 degrees F to reach the freezing point?
• Where does low pressure liquid refrigerant enter a horizontal shell and tube type evaporator?
• If five pounds of water are at 50 degrees F, how many BTUs must be removed to freeze it completely?
• How can the amount of superheat produced in an evaporator be determined?
• Which gas law relates the volume of a gas to its temperature at constant pressure?
• What is a significant advantage of indirect refrigeration systems?
• In an air-cooled condenser, what does the outside air do?
• What distinguishes a centrifugal compressor from a reciprocating compressor?
• What is a key characteristic of an open type compressor?
• At which point in an evaporator coil are the pressure-temperature chart values indicated?
• If the outside temperature drops by 10 degrees Centigrade, how many degrees does it drop in Fahrenheit?
• In a refrigeration system, which process occurs within the evaporator?
• What is the absolute pressure at sea level typically considered in PSIA?
• How is the refrigerant discharged in a double acting compressor?
• What is the main drawback of an open type compressor?
• What condition applies to high pressure refrigerant entering a shell and tube condenser?
• What happens to the refrigerant flow if an orifice plate is partially blocked?
• A double acting compressor has which of the following operational characteristics?
• What happens to the evaporator in a refrigeration system with low condenser pressure?
• Which refrigerant has operating pressures that exceed 1000 PSIG?
• What is the primary function of hydrostatic testing?
• How does the suction pressure change when the evaporator load decreases in a continuously running compressor?
• What is the primary role of a capillary tube in a refrigeration system?