RMO Real Engineer Practice Exam

These questions are part of the practice quiz. Start practicing

• What effect does mixing refrigerant with water have in a mechanical system?
• What type of refrigerant is typically found in the feeler bulb of a system?
• What indicates a need for preventive maintenance in refrigeration units?
• What will happen if a low-side float is being used in a refrigeration system?
• In an ammonia absorption system, where is the satellizer located?
• What is a likely cause of oil foaming in the crankcase of an R12 reciprocating system?
• When is damage most likely to occur in a centrifugal pump with a defective vertical check valve?
• If 500 BTUs are removed from 50 lb of water at 60°, what is the final water temperature?
• What is the most likely cause if a condenser water pump is captivating in a refrigeration system using R22 refrigerant?
• If a pressure relief valve is set to unseat at an evaporator pressure of 15 psi, what is the corresponding set pressure in inches of Hg?
• What does raising the condenser liquid level to maximum primarily achieve?
• At what temperature does a fusible plug typically melt?
• What is the effect of superheated vapor on a compressor?
• What is the primary function of a filter drier?
• What is the expected effect if an operator throttles back on the discharge valve of one of two parallel centrifugal condenser water pumps, while one is at maximum pumping rate?
• Which refrigerant system is most likely to leak within buildings being cooled?
• What contributes to the heating of the equipment in an induction motor?
• When running three compressors, how would you best describe the state of refrigerant leaving the third evaporator coil?
• What factor influences the operation of a water regulating valve installed in a water-cooled condenser?
• What material is a reciprocating compressor shaft seal commonly made from?
• How does a solenoid valve function?
• How far must the outlets from a fan or air duct used to ventilate refrigerants be from any air intake or exhaust openings in adjoining buildings?
• Where are the suction and discharge valves located in a reciprocating compressor?
• Which type of refrigerant systems is most likely to experience leaks into building spaces?
• What does not occur when using glycol compared to sodium chloride as a brine?
• What type of refrigerating systems require an automatic purge unit?
• What could be a possible cause for a ruptured breaker on a larger centrifugal package system?
• In what order are accessories on the liquid line arranged?
• Wearing rings are used primarily for what purpose?
• Why is it generally not recommended to use a halide torch outside on a rooftop for leak detection?
• What is the primary function of a water regulating valve connected to the outlet of the condenser?
• What could cause excessive superheat at the evaporator outlet?
• What is the most likely cause of significant drops in crankcase and compressor discharge temperature along with high suction line pressure in a refrigerating unit?
• Which type of bearing is primarily used for turbine rotor shafts?
• What happens to the evaporator if there is a disconnect of the external equalizer line during a 5 lb pressure drop?
• What can compound gauges measure?
• In an induced draft cooling tower, what is the lowest temperature achievable?
• What does a high-side float metering device control in a condenser?
• What typically controls a solenoid valve on a motor?
• After recovering all liquid refrigerant during a system overhaul, what is the next step?
• Quick-connect fittings are considered to be what type of fittings?
• What is one potential disadvantage of using refrigerants that contain chlorine?
• What is a major advantage of using a two-stage centrifugal compressor with impellers back-to-back?
• What is the primary function of a lift pump?
• What is the purpose of the steam jet on a surface condenser?
• In a dual pressure relief valve system, what valve should be installed to work on one pressure relief valve while allowing the other to operate?
• What is the main disadvantage of the suction line filter drier compared to the liquid line filter drier?
• When throttling back on the discharge valve of one of two centrifugal condenser water pumps running in parallel, what is the most likely effect?
• When performing system maintenance, why is it important to monitor the temperature of the compressor?
• Why is copper used in refrigeration systems, particularly in heat exchangers?
• When replacing the gauge on the high side of a refrigeration system, what should the pressure graduation rate be set to?
• What is a potential consequence of low refrigerant levels in a refrigeration system?
• In case of suspecting shorted motor windings, which tool should an operator use for investigation?
• If the resistance in an electric motor is cut in half, what will happen to the motor power, all else being equal?
• In the context of water-type evaporators, what benefit does the automatic expansion valve provide?
• What is the main effect of a non-feeding expansion valve in a refrigerating system?
• What is a common component of a refrigeration system that splits the workload when multiple units are operating?
• When charging a centrifugal system, what position should the valve be in?
• Which of the following is a sign of potential refrigerant leak in a cooling system?
• What material is the valve plate made of in a compressor that uses a shaft with a mechanical seal?
• In terms of HVAC systems, what does BTU stand for?
• If the pressure at the expansion valve of the evaporator is reduced, what is the main outcome for the refrigerant?
• If a refrigeration unit is short cycling and using a low side float valve, what is indicated?
• What should be checked regularly to ensure optimal performance of a lift pump?
• Why do Cascade systems utilize two compressors?
• What best describes the state of refrigerant leaving the third evaporator coil when running three compressors?
• If refrigeration oil has a low viscosity number, what does this indicate?
• If a centrifugal pump loses water flow when throttled, what is the most accurate assumption?
• How is a wattmeter typically utilized for accurate readings?
• Which refrigerant state indicates that the system is ready to absorb heat?
• What does an electrical wiring schematic show?
• In multistage centrifugal compressors, what is true about each stage?
• What is the function of the crankcase heater in a refrigeration system?
• What is a safety head in a refrigeration system?
• When a thermostat expansion valve is operating properly, what state will the end of the coil contain?
• Where does oil settle after circulating in a centrifugal machine, and how is it extracted?
• What is the function of solenoid unloaders in reciprocating compressors?
• What additional function may a cylinder unloader have besides controlling capacity?
• A compressor with a safety head implies what?
• What is the most likely cause of increased superheat temperature for refrigerating fluid entering a reciprocating compressor?
• How many BTUs are required to raise 10 lb of water by 1 degree Fahrenheit?
• What is the most likely cause of frost on the suction line and compressor during operation?
• In a low-pressure refrigeration system, what is the expected result of a pinhole leak in the evaporator?
• What conditions must be met for a centrifugal water pump to be correctly primed?
• What happens to system efficiency if the refrigerant storage limit is exceeded in a machinery room?
• What is true about compressor motors that operate inside the refrigerant atmosphere?
• Which electrical component is known for its ability to store electricity and is often used to start motors?
• What is the characteristic of an oil with low viscosity in refrigeration applications?
• In a system containing 50 lb of refrigerant, where should stop valves be installed?
• How many BTUs are absorbed by 5 tons of ice?
• How does a sharp drop in outside temperature affect a reciprocating machine's operation?
• What device would you use to convert 110 volts to 24 volts in a system?
• What is the total maximum amount of refrigerant that can be stored in a machinery room apart from the refrigerant in the machine?
• What is the standard practice for checking compressor oil levels in a refrigeration unit?
• What color would the cylinder used to store R22 refrigerant have?
• When starting an additional reciprocating machine, what is the first action an RMO should take?
• Which of the following is considered the most undesirable property in refrigerants?
• What type of valves should liquid level gauge glasses have?
• How do you calculate the cubic feet of a vessel that is 20 feet long and 6 feet wide?
• What occurs when you remove the insulation on the suction line with the engine temperature at 85 degrees Fahrenheit?
• In the absence of an equalizer line, what component would you typically find associated with the evaporator?
• Why are two low side floats placed in parallel?
• Which refrigerant is considered non-flammable and non-toxic?
• What is a common use for quick-connect fittings in HVAC systems?
• If 10 BTUs are transferred to 10 lb of water, what is the closest increase in temperature?
• In a refrigeration system, what is the purpose of using a halide torch?
• What action should an operator take if the wet-bulb temperature drops by 5 degrees while the dry-bulb temperature remains constant?
• If cycling times on a reciprocating refrigerating unit are normal but temperature readings are outside the normal rate, what should be inspected?
• What is the most accurate description of a brazed joint?
• What is used to track the speed of a steam turbine?
• What unit is commonly used to measure refrigeration units?
• What advantage do shell and tube condensers have?
• What is a major disadvantage of using water with refrigerants in systems?
• Which ANSI/ASHRAE refrigerant safety classification is considered the most dangerous?
• How do automatic expansion valves respond when the load increases in a refrigeration system?
• If a compressor is receiving liquid refrigerant, what is a noticeable consequence?
• Why cannot a flare fitting be used for sizes 3/4 inch or larger?
• In systems with a safety head, what is the main purpose of the pressure relief valve?
• What is a common indicator of a clogged filter in a refrigeration system?
• If a motor pulley has a diameter of 3 inches and runs at 1400 RPMs, what is the RPM of a fan pulley with a diameter of 5 1/4 inches?
• In which circumstance would a reciprocating compressor typically experience pump-down operation?
• If 1000 BTUs are removed from 100 lb of water at a temperature of 55 degrees Fahrenheit, what is the final water temperature?
• Which type of recovery machine is used to recover refrigerant from the system without utilizing the system compressor?
• When adjusting refrigerant flow, what should be monitored to ensure efficiency?
• What is the primary purpose of the condenser in a refrigeration system?
• What state of the refrigerant is expected when leaving the third evaporator coil in a system with three compressors?
• What essential information must be stamped on a fusible plug?
• What is a primary reason for installing a crankcase breather line in a refrigeration system?
• What is the best method to increase the pressure of a centrifugal compressor?
• What is the maximum water temperature recommended when charging an R12 reciprocating refrigeration system?
• What role does superheat play in the refrigerant cycle?
• Ventilation in the machine room depends on what factor?
• Why is copper commonly used in heat exchangers within refrigeration systems?
• When an evaporator is not equipped with an equalizer line, what component would you most likely find?
• To prevent structural collapse in pipe work when installing bent copper tubing, what should be done?
• Which of the following is NOT a problem associated with excessive superheat?
• When assessing refrigerant oil quality, which characteristic is the least desirable in the oil?
• According to ANSI/ASHRAE fire safety classifications, which classification indicates the least toxicity and latest flammability?
• What occurs to the pressure in a three-stage centrifugal chiller as it reaches the final stage?
• What type of valve would you install to isolate a dual pressure device while keeping the system operational?
• What formula best describes the true power consumed by an induction motor?
• In shell and tube condensers, what does not have to be disrupted for cleaning?
• Why is adjusting the size of the vane passages important in a centrifugal compressor?
• What system component regulates refrigerant flow in a system requiring continuous variation?
• What type of vapor treatment is typically avoided in refrigeration systems?
• If a compressor is operating normally but short cycles due to throttling down, what is a likely cause?
• Orphus plates in a centrifugal system serve as a metering device, but what additional function does the vessel provide?
• What component is not included in varied refrigerant flow systems?
• What is the primary function of a recovery machine in refrigeration applications?
• Besides preventing water from leaking, what other function can a pump seal serve in a centrifugal water pump?
• In a reciprocating system using an evaporative condenser, where is the muffler typically installed?
• At what pressure would the relief valve typically start functioning in a refrigerating system?
• What component is necessary when a system does not have unloaders?
• At which point in operation does a pump seal primarily prevent air from entering?
• What should be monitored in the cooling system to ensure optimal performance during temperature fluctuations?
• How is the capacity of a centrifugal compressor controlled using variable guide vanes?
• Why is copper commonly used in refrigeration systems, particularly in heat exchangers?
• What is the maximum percentage of refrigerant that can be stored in a cylinder?
• When is a centrifugal water pump considered a lift pump?
• What does the evaporator's performance depend on in refrigeration cycles?
• In a swirl condenser, what direction does water flow through the tubes?
• What types of refrigerants are prohibited from being dumped?
• On a valve plate, where are the suction and discharge valves located?
• In refrigeration, what does the term "vapour" primarily refer to?
• What is one of the primary functions of a mechanical seal in a compressor?
• What is the minimum height level required for exhaust inside a machinery room?
• What is the usual pressure setting for a pressure relief valve installed on a reciprocating compressor using R12?
• At what pressure would a relief valve in a refrigerating system typically start functioning?
• What is the potential issue when using a constant pressure expansion valve instead of a thermostatic expansion valve under various loads?
• What should be done with bent copper tubing to maintain integrity during installation?
• What action should be taken if the compressor discharge temperature is excessively high?
• What function does the automatic expansion valve serve in a refrigeration system?
• After detecting a leak using a mixture of nitrogen and trace R22, what should be done with the mixture?
• In a commercial refrigeration system, the liquid line solenoid valve is controlled by which device?
• What can the RMO do to obtain a temperature reading from the suction line if no gauges are available?
• What is the preferred solder for joining copper, iron, or steel?
• What is the consequence of a restricted jet ejector raising oil mixed with refrigerant?
• Which refrigerant is not used as a cooling medium in an indirect refrigeration system?
• When the piston is at top dead center, what is the position of the valves?
• The role of a filter drier in a refrigeration system includes which of the following?
• If unloaders fail in the unloaded position in a reciprocating compressor system, what is the expected outcome?
• What is the advantage of charging a refrigeration system with vapor?
• What action should be taken when the temperature and load increase, requiring another pump to be added online?
• Which type of refrigeration system is most likely to leak refrigerant into cooled building spaces?
• How does a reciprocating compressor typically vary its capacity?
• Which of the following is NOT a property of an ideal refrigerant?
• What type of pump is commonly used in chilled water systems?
• What is a disadvantage of flooded evaporators?
• What happens when an operator throttles back on the discharge valve of a centrifugal condenser water pump running in parallel with another pump?
• When using a clamp-on ammeter to read the HP of a 3-phase motor, what does the ammeter read?
• Under what conditions is the heat absorbed by the condenser water in a refrigeration plant usually greatest?
• How does a compass affect the pressure of a fluid or gas?
• What is the first evidence of failure to maintain water treatment in a condenser?
• How does the strength of the strong liquor in an absorption system change with evaporator load?
• What safety procedure should an operator follow before starting a large reciprocating machine without unloaders?
• How does the heat transfer rate in the condenser behave with respect to the velocity of water in the tubes?
• How is capacity control typically achieved in a reciprocating compressor?
• Where should the bulb of the thermostatic expansion valve be attached during a routine inspection?
• What is the main function of the evaporator in a refrigeration system?
• Which type of condenser utilizes both air and water for cooling?
• What does it indicate when both dry bulb and wet-bulb temperatures are at 75 degrees Fahrenheit?
• Where is the heat finally rejected in a refrigeration system with a draft cooling tower and an economizer?
• What characteristic is crucial for the operation of a low side float valve in a refrigeration system?
• What is the auxiliary oil pump mainly used for?
• During the purging process, what is the correct procedure?
• What potential issue could arise if a refrigeration system is not properly evacuated before charging?
• What is the purpose of a service valve stem cap?
• What would likely happen if an automatic water regulating valve is malfunctioning?
• During an inspection, what is the first evidence of insufficient water treatment in the condenser water?
• What is one characteristic of the globe valve?
• Which component is primarily responsible for heat absorption in a refrigeration system?
• When will the BTUs absorbed by the condensing water be the greatest?
• When a refrigeration unit experiences short cycling, what is the most likely service requirement?
• What happens to pressure in a three-stage centrifugal compressor?
• In a system without unloaders, what is necessary to manage the capacity?
• What is a refrigeration accessory primarily used for?
• Where is the rupture disk always piped into?
• What type of heat is released in a condenser as refrigerant boils off?
• What is the typical warm-up period for a steam turbine?
• Which type of brine is not recommended for use in indirect cooling systems?
• What is a common characteristic of a low-viscosity refrigeration oil?
• What is a potential consequence of insufficient airflow over the evaporator?
• If you have 62 PSI at 35 degrees Fahrenheit and 70 PSI at 45 degrees Fahrenheit, what would be the pressure at 38 degrees Fahrenheit?
• What is one method to reduce water treatment issues in a condenser system?
• In a 3-line cable supplying energy to equipment, which line should not be used if only two lines are fused?
• What is the primary purpose of solenoid unloaders on reciprocating compressors?
• What is the primary capacity control mechanism in a centrifugal system?
• What happens to the latent heat of evaporation if an external equalizer line disconnects during operation?
• What component starts the compressor again if the low-pressure cutout cycles it off?
• How can a brazed joint be accurately described?
• Which valve is most likely to cause leakage?
• If the machine does not start and the electrical components are functioning properly, what should be the next check?
• What is typically done to avoid frost formation on suction lines?
• What is the primary function of the evaporator in refrigeration systems?
• What is the first step to add another pump online?
• What process occurs when water turns to ice?
• What is the significance of measuring suction pressure in refrigeration systems?
• If evaporator pressure is reduced at the expansion valve, what is the result for the refrigerant?
• In a three-stage centrifugal chiller, what happens to the pressure as it reaches the final stage?
• What should the size of a ventilation system for refrigerant removal be based on?
• How is electric power delivered to a liquid line solenoid valve measured?
• If the suction pressure is 60 PSIG and the discharge pressure is 180 PSIG, what is the compression ratio?
• What might indicate that a compressor is receiving liquid refrigerant?
• R11 and R-123 refrigerants are categorized as?
• How does high thermal conductivity benefit refrigeration systems?
• Why might a refrigeration system need to have an equalizer line?
• How is the proper water level maintained in the hot well?
• How can the efficiency of the refrigeration cycle be improved with regard to the operation of the condenser?
• In commercial refrigeration, what does the thermostat primarily control?
• How does the operation of a condenser affect the efficiency of a refrigeration cycle?
• At an evaporator temperature of 38 degrees Fahrenheit, what should be the suction pressure for R22 refrigerant?
• Which statement is true regarding the usage of capacitors in electrical systems?
• What result may occur if the Eliminator plates in an induced draft cooling tower become clogged?
• To produce a colder water supply in an assembly room experiencing increased temperature, what should an operator do?
• What occurs if an external equalizer line disconnects and there is a 5 lb pressure drop across the evaporator?
• What would happen if the unloading fails to operate when needed in a refrigeration system?
• What does the combination of current and voltage yield in electrical terms?
• What is the outcome of unraveling the insulation on a thermal bulb attached to a discussion pipe in a refrigeration system?
• Which type of valve should be used to minimize pressure drop?
• After the compressor, what role does the oil separator play?
• What is the primary purpose of the gland steam in mechanical systems?
• In refrigeration systems, what does the term "back seated" refer to?
• What might cause uneven temperature distribution in a refrigeration system?
• Where do non-condensable vapors and moisture typically collect?
• What safety procedure should be followed when starting a larger reciprocating machine without unloaders?
• In a reciprocating chiller, if the water is entering the condenser at 85 degrees Fahrenheit and leaving at 88 degrees Fahrenheit, what could be causing the change if there are no other issues?
• An open type compressor keeps the refrigerant from escaping by using what type of seal?
• In a system with a 150 lb refrigerant charge, where would stop valves typically be found?
• During an engine-room walk-through, excessive superheat at the evaporator outlet could most likely be caused by?
• If a chemical treatment is temporarily unavailable, what adjustment can be made to the cooling tower?
• What could be a cause of decreased efficiency in reciprocating compressors working in an operating clamp?
• What are recovery requirements for low-pressure appliances?
• How is capacity control most likely achieved in a centrifugal compressor?
• What happens to refrigerant as it moves through the system under proper operating conditions?
• Which condition could lead to flooding in the evaporator?
• If a centrifugal chiller has a suction pressure of 18 in HG vacuum and a discharge pressure of 6 PSIG, what is the compression ratio?
• What should a refrigeration unit operator do if the motor compressor is short cycling and using a low side float valve?
• When converting 20 PSIG to absolute pressure in inches of Hg, what is the resulting value?
• How does a low refrigerant charge affect a hermetic compressor?
• What condition could lead to excessive cycling of the temperature control in a reciprocating compressor refrigeration unit?
• When water is mixed with refrigerant in a reciprocating system, what is the consequence?
• What likely cause would result in frosting on the suction line and part of the compressor?
• If a low-side float is being used, what is its main function?
• Unloaders are primarily used to achieve which of the following?
• Why is the refrigerating effect always a lower value than the latent heat?
• What is a critical aspect of maintaining compressor efficiency?
• What is likely to occur if the thermal bulb is improperly insulated in a refrigeration system?
• Which type of pump is commonly used in a refrigeration system for circulating water?
• At 70 degrees Fahrenheit, if R11, water, and lubricating oil are mixed in a container, in what order will they settle from top to bottom?
• What is the main purpose of the condenser in a refrigeration system?
• How many BTUs would be removed in a 30-ton system per hour?
• What is the main reason for regular maintenance of refrigeration systems?
• What would most likely happen if there is a sharp drop in outside temperature affecting a reciprocating machine?
• If an evaporator is not equipped with an equalizer line, what component is likely present?
• If an electric motor is rewound to cut its resistance by half, what effect does this have on motor power?
• What is the function of the overspeed trip in mechanical systems?
• If 1000 BTUs of heat is added to 100 lb of water, how much does the temperature of the water increase?
• The center part of the gauge manifold is connected to which of the following?
• How would capacity control be achieved in a reciprocating compressor?
• What is the primary role of a suction line filter drier in an HVAC system?
• What is a feature of the automatic expansion valve used instead of a thermostatic expansion valve?
• Which metering device is most commonly used in commercial refrigeration systems over 3 tons?
• What consequence could result from freezing water in the tubes of a refrigeration system?
• What is the most probable cause of knocking in a reciprocating compressor?
• What is the most likely cause for a chiller water pump malfunctioning in a refrigeration system using R123?
• What does a high-side float in a condenser primarily control?
• Before using a voltmeter, a technician should always set the range selector to what?
• Where should liquid stop valves be placed in the high side of a refrigeration system?
• Why is glycol considered a better brine than sodium chloride?
• What component is critical for balancing pressures in refrigeration systems without an equalizer?
• What is the operating force on a water regulating valve installed in a water-cooled condenser?
• Which of the following is an important consideration when assessing suction line filter drier functionality?
• What type of seal prevents vapor from leaking out of a compressor?
• Under what conditions is the heat absorbed by the condenser water in a refrigerating plant the greatest?
• Ideal conditions for a suction line in a refrigeration system require which temperature monitoring?
• What is the primary way to achieve capacity control in a centrifugal compressor?
• What best describes the refrigerant in the last evaporator coil?
• What component needs to be replaced after installing a new valve plate on a reciprocating compressor?
• An electric motor rated at 3 horsepower will use which type of power system?
• If a condenser is 20 ft long and 6 ft in diameter, what is the volume in gallons?
• In relation to valve applications, which kind is typically used for throttling?
• Which condition is likely to increase compressor wear?
• What is the pressure of R22 at 41° Fahrenheit?
• What effect does clearance volume have on a compressor?
• If a compressor is said to have a safety head, what does this imply?
• If the suction service valve on a reciprocating machine is front seated and the low side pressure rises immediately after shutting off the can pump, what is likely the cause?
• Under what conditions is the heat absorbed by the condenser water in a refrigerating plant usually greatest?
• What happens if a reciprocating compressor constantly receives liquid refrigerant?
• How does increasing the speed of a motor affect a centrifugal compressor?
• Which safety measure is crucial when working with refrigerants?
• What would be the approximate volume of refrigerant in a reciprocating refrigeration compressor with a 12-inch bore and 16-inch stroke?
• What can result if the solenoid valve malfunctions in a refrigeration cycle?
• When replacing the gauge on the high side of a refrigeration system, what is the minimum pressure graduation rate recommended?
• Centrifugal compressors typically use which type of refrigerant?
• What is the key reason for using a vapor-based refrigerant charging method?
• What impact does clearance volume have in a compressor?
• In a mixture of water and lubricating oil at 70°F, which would settle first in a container?
• What is one consequence of high crankcase temperature in a refrigeration unit?
• After leak testing with nitrogen and R22, what should be the next step?
• If a centrifugal pump operates at 92 feet head, what would be the corresponding pressure in PSIG?
• What is the primary reason for ensuring proper refrigerant recovery?
• Why is a low condensing pressure problematic in a refrigeration system?
• In addition to evaporator pressure, what is another force that determines the flow through an automatic expansion valve?