RMO REVIEW EXAM QUESTIONS WITH CORRECT ANSWERS

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: - ANSWERSLowering the condensing pressure The heat removed from the refrigerant in a condenser is: - ANSWERSSensible and latent heat Which of the following best describes how the cylinder unloader work? - ANSWERSKeep in the suction valve opened while the compressor is in the return stroke The amount of refrigerant that flows through the orifices of a economizar is determined by the: - ANSWERSDifference between the high side and low side pressure A superheated vapor is a: - ANSWERSDry vapor above the saturation temperature A refrigeration engineer verifies thats a condenser water pump is cavitating. Of the following the most likely causef o r this condition is: - ANSWERSA faulty cooling tower water level controller A centrifugal water pump is known as a lift pump when the: - ANSWERSthe water supply t o the pump suction inlet is below the pump level A TXV is used to maintain constant: - ANSWERSEvaporator superheat 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? - ANSWERSYes, this temperature is too high for human comfort purpose The packing gland of a centrifugal pump serves to: - ANSWERSThe drip part of the packing gland gives evidencethat there is water in the pump Capacity control of a reciprocating hermetic compressor is typically achieved through - ANSWERSOperation of the hot gas bypass valve The most important reason to sub-cool the refrigerant in the condenser is to ensure that: - ANSWERSA pure liquid refrigerant will enter the metering device A low side float valve is used to maintain: - ANSWERSThe level of refrigerant ni the condenser Regarding firesafety, which ASHRAE refrigerant safety classification indicates no flammability and lowertoxicity? - ANSWERSA1 When an expansion valve is operating properly, at the end of the evaporator will contain: - ANSWERSOnly superheated vapor In a steam turbine, what is the function of the Kingsbury thrust bearing - ANSWERSMaintain axial positioning of the rotor shaft 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 - ANSWERSLever type tubing bender A reciprocating compressor is making a knocking sound during operation. parts are not causing the knocking, what is probably the cause - ANSWERSThe slugging of the liquid refrigerant In order for a refrigerant to become superheated it must be heated in a section of the low side refrigerant line: - ANSWERSWhere no liquid refrigerant is present All liquid has been recovered from a system to be overhauled, the system - ANSWERSShould not be opened until all vapor has been recovered 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? - ANSWERSAdd additional make up water to cooling tower What device protects the steam turbine from excessive speed? - ANSWERSGovernor assembly Refrigerants are characterized by their physical properties included flashpoint, refrigeration effect, and others. Of the refrigerants in commercial and industrial the highest latent heat and refrigerant - ANSWERSAmmonia On what characteristics is ASHRAE refrigerant safety group classification system: - ANSWERSflammability and toxicity Of the following, an example of an in-line refrigerant cleaning system that may be used with a centrifugal compressor containing R123 refrigerant is: - ANSWERSRefrigerant recycling Information about the physical and chemical properties of a hazardous material can be found in: - ANSWERSMaterial Safety Data Sheet A multi-cylinder reciprocating compressor uses cylinder unloaders to regulate capacity, what would not occur if some of the unloaders fail to operate when needed? - ANSWERSThe discharge pressure wil increase A water chiller system uses refrigerant R123. Aleak in the evaporator shell mat result in - ANSWERSSetting of the refrigerant monitor alarm Capacitors are used on refrigeration motors. Of the following, the function of these devices is to? - ANSWERSStore electrical charges during starting and running the motor Of the following, centrifugal refrigerant machine is best characterized by: - ANSWERSHigh volume low pressure machine Which of the following ASHRAE refrigerant safety classification is the most flammable? - ANSWERSA3 Which of the following correctly describes theobject in the picture below? - ANSWERSStandpipe hose outlet, to put out fires in case of emergency Modern compressors usually seal the rotating shaft as it exits the loaded seal made of - ANSWERSMetal or carbon The British Thermal Unit (BTU) is the measurement of heat ofenergy. 10 pounds of water, If 10 BTU are transferred to the water temperature increase will be closest to: - ANSWERS1F A reciprocating compressor cylinder has a 10inches bore and 14 inches volume of refrigerant,in cubic inches, will be closer to V=3.14xrxrxL V=3.14x5(5)x14 V=1099.3 in3 - ANSWERS1099 An electrically operated control requires 24 volts to operate. to change the available 110 volts to 24volts - ANSWERSTransformer In a n indirect refrigeration system, oft h e following, the one thatwould not be used medium fort h e building spaces being cooled is: - ANSWERSR22 refrigerant On a steam turbine, what would cause the atmospheric valve to open? A. Low vacuum int h e surface condenser B. Leaking tubes in the surface condenser C. All answer are correct D. Dirty tubes in the surface condenser - ANSWERSAll answers are correct Electric devices may be used to provide built in defrosting of refrigeration machine evaporator units. These devices are classified as - ANSWERSResistors The flash point of Compressor lubricating oil: - ANSWERSShould be higher than the compression temperature The primary way of achieving capacity control of a centrifugal compressor is by; - ANSWERSAdjustment of the impeller inlet pre-rotation vanes Cooling tower water requires the addition of chemical additives in order to: - ANSWERSReduce the formation of scale and algae In the picture below describe the equipments function? (Vacuum Pump) - ANSWERSRemove non condensable from the condenser The viscosity of lubrication oil is described by a number. A low viscosity number describes oil that: - ANSWERSFlows easily The most important reason to use at least two compressors in a cascade system is to: - ANSWERSAvoid very high compression ratio for each compressor According to the attached Material Safety Data Sheet (MSDS) R134 is a - ANSWERSClear,odorless liquid and vapor Under normal condition, the refrigerant enters the compressor as a : - ANSWERSLow pressure superheated vapor and leaves as a high pressure vapor While operating an R-22 single acting compressor system, the refrigeration engineer noticed oil foaming in the crankcase. This condition most likely, would have been caused by a - ANSWERSSudden drop in the crankcase pressure Assume that an engineer is able to observe refrigerant water and oil together. The fluids would settle in the container from top to bottom: - ANSWERSOil, water, refrigerant What is the function of the vacuum breaker in a steam turbine ? - ANSWERSTo achieve a faster coast down cycle An equalizer line on a TXV is used to: - ANSWERSCompensate for the pressure drop across the evaporator coil In a multi stage centrifugal compressor, each stage: - ANSWERSIs identical in volume to the other stages A refrigeration engineer notices excessive cycling of the temperature control for a reciprocating compressor refrigeration unit. The crankcase temperature is high, the compressor discharge temperature low, the suction line temperature is high. of the following the one that may be causing this set of condition. - ANSWERSFaulty compressor valves On an operating centrifugal compressor refrigerant unit, the refrigeration engineer notices that the compressor is short cycling. The unit is using a low side float valve as a metering device. Of the following requirements, this would indicate that: - ANSWERSThe system is undercharged with refrigerant The vessel depicted below may be used in connection with - ANSWERSRefrigerant recovery 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: - ANSWERSThere may be insufficient head to lift the oil The advantage of forced draft cooling tower over natural draftcooling towers is: - ANSWERSSmaller tower size The sole refrigeration engineer on duty in a building is permitted to leave the building refrigeration system when it is in operation only when: - ANSWERSrelieved 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: - ANSWERSRefrigerant overcharge Which of following is a correct statement? 1gal of water = 8.33 lb - ANSWERS2.5gallons of water weighs 20.8 pounds 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? - ANSWERSPlug valve Where must the Material Safety Data Sheets be located ? - ANSWERSWhere available to al employees What is the function of gland steam? - ANSWERSseal the turbine rotor carbon rings