Refrigeration License Review Exam Questions and Complete Solutions.

Refrigeration License Review Exam Questions and Complete Solutions At the condenser refrigerant enters as - Answer: high pressure gas and leaves as high pressure liquid If you were running three compressors, - Answer: highly superheated vapor describes the state of the refrigerant leaving the third compressor the state of refrigerant as it leaves the compressor is (blank) and as it leaves the condenser is (blank) - Answer: compressor-super heated vapor condenser- warm sub-cooled liquid. if you want to check if a thermometer is working - Answer: you would touch it to a bucket of ice/ice water when changing water to ice - Answer: latent heat must be removed a refrigeration unit is measured in - Answer: btus how many btus would be removed in a 30 ton system @12,000/hr - Answer: 360,000 btus @ 12,000/hr any heat that is boils off is - Answer: latent heat the ratio of actual pressure of water vapor in the atmosphere to the saturation pressure/temperature is called - Answer: relative humidity the dividing line between the highside and lowside of the refrigeration system is - Answer: the compressor outlet and the orifice of the metering device what does oil in a refrigeration system do? - Answer: it reduces wear and friction lubricates bearings, like skateboards in a well designed compressor the percent of the lubricant circulated should not exceed - Answer: 10 percent oil foaming in the compressor is a result of? - Answer: liquid refrigerant in the crankcase Refrigerant oil quality is measured in viscosity,the least desirable quality in the oil would be - Answer: low viscosity/ =flow too easily unloaders are used to - Answer: reduce capacity the cylinder unloader controls? - Answer: controls capacity and another function is that it assists with compressor start up an operator has been assigned to run a reciprocating compressor. what is the achieved action of capacity control? - Answer: opening the suction valves with some form of control is the most likely achieved action of capacity control the solenoid unloaders on a reciprocating compressor are designed to - Answer: unload the clearance spaces in the cylinders what would happen if unloaders were to fail in the unloaded position - Answer: Not enough refrigerant will flow to the evaporator coil, the evaporator will then starve causing high superheat in a system using a reciprocating compressor when a system does not have unloaders - Answer: other capacity control is needed superheated vapor protects the compressor against liquid intake. what may happen if the compressor was recieving liquid refrigerant? - Answer: the RMO would notice frost that may develop in the suction line if the compressor was recieving liquid superheated vapor protects the compressor against liquid intake. One of the problems associated with superheat is that - Answer: it will decrease the capacity of the refrigeration machine an operator has been assigned to run a centrifugal compressor. the capacity control most likely achieved is through - Answer: adjustment of the impeller inlet pre-rotation vanes. a mechanical seal is a - Answer: shaft seal that prevents vapor from leaking out of the compressor efficiency of the refrigeration cycle is affected by the operation of the condenser. A more efficient operation of a centrifugal compressor resulted from - Answer: lower condenser pressure what happens to tip speed of a multistage centrifugal compressor - Answer: increases with each stage in a 3 stage centrifugal chiller, the pressure - Answer: increases as it reaches the final stage. in a centrifugal 3 stage compressor impeller are the same size but - Answer: the pressure increases with each stage Semi-Hermetic Compressors may be better to use than hermetic compressor because - Answer: hermetic compressors are fully enclosed and cannot be serviced on site a pressure relief valve that is installed on a reciprocating compressor using R-12 is normally set according to - Answer: design pressure the centrifugal compressor generates - Answer: high volume and low pressure (relative) inside. compressor motors the operate in the refrigerant atmosphere (atmospheric) must use materials - Answer: compatible with the system refrigerants, motors must be assembled in clean atmosphere and kept dry, and are not worked on in the field. in relation to suction pressure of a compressor the reading of the oil pressure gauge should read - Answer: 15-30 psi higher. Clearance volume effects - Answer: compressor capacity what is the reason for the compressor inlet being larger than the compressor outlet? - Answer: pressure drop in the suction line increases the volume of gas that must be handled by the compressor for a given tonnage. what are the conditions that would cause the greatest heat in btu/hr min absorbed by the condenser water in a refrigerating plant? - Answer: low evaporative and high condenser temperatures are the conditions that would cause the greatest what will cause the greatest btus absorbed by the condenser water? - Answer: high condenser temperature and low condenser water temperature if you subcool the refrigerant it will - Answer: enhance the refrigeration effect if the refrigerant is entering the subcooling tubes of the condenser as a gas then, - Answer: the system is short of refrigerant if a centrifugal compressor is being used in a refrigeration system and is affected by the condenser, the condenser may be improved by? - Answer: increasing the amount of subcooling what is the advantage of shell and tube condensers? - Answer: they have the advantage of being able to remove the heads for cleaning the water side of the tubes and the refrigerant connections does not have to be disrupted. shell and coil condensers have the advantage of? - Answer: having less of a chance of developing leaks. what kind of condenser uses air and water for cooling - Answer: the evaporative type non-condensable vapors collect in? - Answer: the condenser assuming that a refrigeration plant uses a horizontal shell and tube condenser with the water in the tubes and the refrigerant in the shell. In controlling the operation of the condenser, the operator should take into account that most likely the heat transfer rate btu/per sq ft per second in the condenser will? - Answer: increase with the velocity of the water in the tubes. how do you clean the tubes of a shell and tube condenser? - Answer: by punching the tubes manually when the system is shut down. Fan cycling devices, variable speed fan motors, dampers, and hold back valves causing condenser flooding is used on ? - Answer: air cooled condensers in low ambient conditions (winter) air, nitrogen and non-condensables will collect in the - Answer: condenser low condensing pressure is not good because - Answer: expansion valves will not feed properly in addition to regulating the refrigerant flow according to the needs of the system, metering devices also - Answer: serve to restrict flow of refrigerant from the high side to the low side the most common metering device used today in a reciprocating commercial refrigeration system over 3 tons is - Answer: the thermostatic expansion valve (txv) the TEV diaphragm is made of - Answer: metal if the spring in the tev were to break ? - Answer: the evaporator would flood. the purpose of the equalizer line is to - Answer: make up for pressure drop in the evaporator TXV power heads are color coded to match refrigerant charge in the system. what color would be on the power head if the system was charged with R-22? - Answer: green the bulb of the TXV has fallen off and the room is at 85°F. this would cause ? - Answer: the evaporator to flood a thermal bulb is attached to the suction pipe between the evaporator coil and the compressor covered by an insulating line. assuming the matching room is at 85°F. unraveling of the insulation would result in? - Answer: the evaporator to flood. while doing a routine inspection, the RMO noticed the bulb of the TEV on the floor; where should the operator attach the bulb? - Answer: attach the bulb at the end of the coil A constant pressure expansion valve is being used instead of a thermostatic expansion valve. what would happen under various loads? - Answer: it will starve and flood the evaporator AXV maintain constant evaporator pressure, they also - Answer: close when the load increases what closes the (AXV) automatic expansion valve? - Answer: back pressure at the evaporator inlet. in addition to evaporator pressure what other pressure determines the flow through an automatic expansion valve? - Answer: spring pressure the amount of refrigerant that flows through the orifice plate is determined by ? - Answer: the difference between the highside and lowside The metering device used in a condenser is a____________? what does it control ? - Answer: it is a highside float and it controls the amount of refrigerant in the condenser If a lowside float is being used what does it control? - Answer: it controls refrigerant flow. if the evaporator pressure is reduced at the expansion valve what is the result? - Answer: lower boiling point for the refrigerant. copper is used in refrigeration systems, like in heat exchangers, because? - Answer: of it's high thermal conductivity in the refrigeration cycle, heat is absorbed by the refrigerant takes the form of - Answer: latent heat of evaporation During a walk through of the engine room the RMO noticed excessive superheat at the evaporator outlet, this would most likely be caused by? - Answer: a leak in the system, which caused low refrigerant charge, which caused a starved evaporator frost appearing on the suction line and part of the compressor is caused by? - Answer: a flooded evaporator flooded evaporators have high heat transfer per square foot; a disadvantage is that? - Answer: it requires a larger charge a flooded evaporator is more commonly referred to as a ? - Answer: chiller the reason for two low-side floats in parallel would be that? - Answer: each one would feed it's own evaporator if you were running three compressors, what describes the state of the refrigerant leaving the third compressor ? - Answer: superheated vapor when an evaporator is not equipped with an equalizer line, you would most likely find a? - Answer: distributor when there is a 5lb pressure drop across the evaporator, you need an external equalizer line, if it disconnects what would happen? - Answer: the evaporator would starve. A RMO would expect a relief valve to start functioning (for the section of the refrigerating system being protected) at a pressure closest to? - Answer: the design pressure when installing a service valve to isolate a dual pressure device while keeping a system in service you would use a? - Answer: three way valve a spring loaded PRV is better to use than a fusible plug because - Answer: a fusible plug can't be reset information that must be stamped on a fusible plug is the? - Answer: melting point of the alloy. a fusible plug melts at ? - Answer: 280°F the purpose of having a service valve cap is to? - Answer: protect from being inadvertently turned from its position and from being damaged the accessories on the liquid line in the correct order are - Answer: reciever, driver, solenoid valve, and bull's eye sight glass on the highside of the system, where should liquid stop valves be placed? - Answer: in front and after the bull's eye sight glass. a RMO was instructed to charge a 60 ton plant with R-134a refrigerant. the operator would most likely find the charging valve on the? - Answer: low pressure side of the equipment what is a filter drier used for? - Answer: to remove moisture a water regulating valve is installed in a water cooled condenser. the operating force on this valve is respondent to? - Answer: high side pressure a reciprocating system using an evaporative condenser will have the muffler installed between the ? - Answer: compressor and evaporative condenser a RMO needed to vary the flow of refrigerant in a system. a continuous variation in the flow of the system does not include the ? - Answer: solenoid valve after the compressor you have the oil separator, which in general will return the oil to the ? - Answer: crankcase the main disadvantage of the suction line filter-drier compared to the liquid line filter-drier is if - Answer: the suction line filter-drier gets clogged it will reduce more of the capacity of the compressor than the liquid line filter-drier. According to the NYC fire code classification of refrigerant, ammonia would fall under which group classification? - Answer: group 2 refrigerants are characterized by the physical and chemical properties including latent heat, boiling point, refrigeration effect and others. of the refrigerants in commercial industries used today, the one with the highest latent heat and refrigeration effect is? - Answer: Ammonia the most undesirable property in refrigerant is ? - Answer: low latent heat Latent Heat and refrigeration effect are usually listed as refrigerant properties. the refrigeration effect is also always a lower value than the latent heat because? - Answer: the heat required to cool the refrigerant compressor discharge to evaporative temperature is subtracted from latent heat Refrigerants have many characteristics. One that describes R22 is that? - Answer: it is odorless when mixed with air R-11 and R-123 refrigerants are heavier than air, oxygen depleting and are class? - Answer: Class 1 and class 2 substances defined by the EPA Assume an operator is able to observe R-11, water and lubricating oil together at 70°F. Under these conditions, the water , moisture and fluids would settle in the container from top to bottom in what order ? - Answer: oil,water,refrigerant. Oil with low viscosity would ? - Answer: not be used for refrigeration Oil flashpoint temperature in the compressor should be ? - Answer: higher than the heat of compression the most important reason to use 2 compressors in a cascade system is to? - Answer: accomplish lower temperature. An operator has been assigned to a large reciprocating machine without unloaders. the proper safety procedure for starting this machine is ? - Answer: suction valve and discharge valve bypasses both open. what happens if unloaders fail to open when needed? - Answer: Evaporator temperature goes down. Due to a cold front, there was a sharp drop in outside temperature. the most likely effect of this condition on the operation of the reciprocating machine would be? - Answer: that the thermostat causes the solenoid valve to close, the compressor pumps down and shuts down on low pressure. a room thermostat controls the liquid line solenoid valve in this commercial refrigeration system. the compressor is activated by? - Answer: the low side pressure stat if the low pressure cutout cycles the compressor off what cycles the compressor back on? - Answer: the low pressure cutout starts the compressor again in an operating plant using reciprocating compressors, the efficiency of one of the compressors has decreased. the cause of this may be ? - Answer: a leak in the suction valve the suction and discharge valves in a reciprocating compressor are positioned? - Answer: both under and over the valve plate Assume that a new valve plate has been installed while they are repairing a reciprocating compressor in a refrigerating plant. the installation of new valve plate will require? - Answer: the replacement of all valve seats one of the primary reasons for the insulation of a crankcase breather line is to prevent? - Answer: oil slugging in the compressor the RMO wants to get a temperature reading from the suction line, but there are no gauges, the RMO should? - Answer: use a thermometer on the suction line for a reading while operating a reciprocating refrigeration system, the RMO noticed that one of the 4 belts is broken. the most advisable course of action for the RMO would be to? - Answer: replace all 4 belts with a new set an open type compressor is keeping refrigerant from escaping by a? - Answer: seal made of carbon and metal centrifugal compressors could use what kind of refrigerants? - Answer: CFCs, HCFCs, HFCs high and low pressure refrigerants a low pressure chillers rupture disc is set at? - Answer: 15 psi a rupture breaker on a large centrifugal package system had lifted. a possible cause for this could be a ? - Answer: ruptured tube in the chiller the rupture disk of the rupture guard is constructed as a - Answer: reverse buckling non-fragmentizing nickel alloy. a rupture disc in a centrifugal refrigeration machine is normally located on the? - Answer: evaporator the rupture disc is always piped into - Answer: the lowside the main capacity control on a centrifugal system is ? - Answer: variable inlet vanes speed control can also be used. the bearing used for the turbine rotor shaft is ? - Answer: a kingsbury bearing capacity is controlled on a centrifugal compressor by - Answer: varying the passages of the vanes with the variable guide vanes while operating an R-12 reciprocating system, The RMO noticed the oil foaming in the crankcase. this condition most likely would have been caused by - Answer: a sudden drop in crankcase pressure if an operator was assigned to run a centrifugal compressor. The capacity control is most likely achieved by? - Answer: adjusting the size of the vane passages An automatic purge unit is required for those refrigerating systems that ? - Answer: operate below atmospheric pressure Orifice plates may be used as a metering device component in a centrifugal system the vessel in which they are contained in can also serve as an ? - Answer: economizer A jet ejector is used to raise oil mixed with refrigerant which has collected at the bottom of the evaporator if restricted? - Answer: you will have insufficient head to lift the oil. An inline refrigerant cleaning system is advisable because? - Answer: refrigerant reacts with the lubricating oil. the recovery requirements for low pressure appliances (manufactured before 11/15/93) is ? - Answer: 25 Hg Vac. while using a halide torch to check for leaks, if the flame was to turn yellow, it? - Answer: it has a restriction in the tube The proper way to start a pump is to? - Answer: make sure the suction valve is open , discharge closed and slowly throttle open discharge. A pump affects the pressure of a fluid or gas by ? - Answer: raising pressure. An operator is running two centrifugal condenser water pumps in parallel; one of the pumps is at maximum pumping rate. If the operator throttles back on the discharge valve of the other pump, the most likely effect would be a ? - Answer: reduction in total flow rate to the condenser. a centrifugal pump is considered a ? - Answer: non-positive displacement pump When the temperature and load increases and you need to add another pump online you would? - Answer: open suction and throttle discharge. An operator suspects that a vertical check valve on a discharge of a centrifugal pump is defective; this is a condenser pump and one of the three pumps in parallel. If the suspicion is true and the check valve fails to seat when required the? - Answer: pump and connecting piping will most likely be damaged when starting up an additional pump. An operator confirms that a chiller water pump in a refrigerating system employing R-123 is cavitating. The most likely cause for this condition is ? - Answer: malfunctioning of the water makeup float valve. An operator verifies that a condenser water pump is cavitating in a refrigerating system employing R-22. The most likely cause for this condition is ? - Answer: faulty cooling tower water level controller. An operator notices that a centrifugal pump operates satisfactorily when delivering at full discharge, but loses water flow if throttled. The operator would most accurately assume that this condition is due to a ? - Answer: Clogged strainer in pump inlet. The petcock located on top of the casing of a centrifugal pump is used to? - Answer: remove air. When a centrifugal pump has the suction inlet of the water source below the pump level, this pump is considered a? - Answer: lift pump what does a lift pump do? - Answer: it actually lifts water to the pump suction. On a centrifugal water pump the conditions are fully primed when it? - Answer: is full of water and all air has been purged out. The pump seal prevents water from leaking on a centrifugal water pump when under positive pressure. It also prevents air from entering when the pump is? - Answer: under negative pressure As an RMO in charge you are requested to replace the gauge on the highside of the refrigeration system. The pressure graduation rate should be at least ? - Answer: 1.2 of design pressure. The most correct way to describe a brazed joint is ? - Answer: gas tight fitting Quick Connect fittings are considered? - Answer: Low-loss fittings When installing a pipeline and you need to make a 90° elbow, you should? - Answer: Use factory made 90° elbows and braze. You are using copper tubing to replace a part of a refrigeration system, what would be used to bend the tubing ? - Answer: the spring type tube bender would be used to bend the tubing Assume that the operator has a choice of 4 valves to select from and wants to minimize pressure drop. the operator should avoid use of a ? - Answer: globe valve Concerning leakage, a gate valve ? - Answer: causes more leakage. To prevent against structural collapse in pipe work, when installing bended copper tubing use? - Answer: a large radius. The middle port on a manifold gauge will be connected to the? - Answer: recovery cylinder or charging cylinder After recovering liquid, you should then ? - Answer: recover vapor After leak detecting with a mixture of nitrogen and a trace of R-22, the RMO can ? - Answer: Vent the mixture into the atmosphere a halide torch is a device not generally used outside because ? - Answer: you will not be able to detect the change in color due to the brightness outside. A reciprocating refrigeration compressor cylinder has a 12" bore and 16" stroke, the volume of the refrigerant in cubic inches would be close to ? - Answer: volume of a cylinder is equal to V= π r□dXh 3.14×36×16= 1808 A condenser is 20' long and 6' in diameter, the volume in gallons if 7.48 gallons is one cubic/ft is ? - Answer: 4227 ??? The cubic feet of a 20ft long 6ft vessel on the evaporator is? - Answer: volume of a cylinder is equal to V= π r□dXh 3.14×9×20=565 You have been informed that the outside temperature has dropped to 10°C. the temperature in degrees F is ? - Answer: 50°F conversion of F to C = F-32 ÷1.8 conversion of C to F = 1.8×C +32 1.8×10+32=50 An operator observes a reading of 60°C on a refrigeration unit. The same reading in Fahrenheit scale would be closer to - Answer: 140°F conversion of F to C = F-32 ÷1.8 conversion of C to F = 1.8×C +32 1.8×60+32=140 when you convert 18" HG vacuum to psia you will get? - Answer: 5.9 psia ??? a centrifugal chiller has a suction pressure of 18" Hg vacuum and the discharge pressure of 6 psig. the compression ratio of this unit is? - Answer: 3.47 ( round off to 3.50:1) ??? If the suction pressure is 60 psig and the discharge pressure is 180 psig, what is the compression ratio? - Answer: 2.6:1 A vertical 12" water pipe from the roof has a pressure gauge reading of 120 psi. how tall would the pipe be? - Answer: 277 feet tall. 1000 btus are removed from 100 pounds of water at a temperature of 55°F. what would be the final temperature? - Answer: The final water temperature would be 45°F what is 29.92 Hg (absolute) In KPA? - Answer: 101.3 An operator reads the valve tag on a pressure relief valve and notices the valve is set to unseat at an evaporator pressure of 15 psi, what is the corresponding set pressure in inches of HG? - Answer: 30.3 If you have 62 psi at 35°F and 70 psi at 45°F, 38°F would be? - Answer: 64.4 psi 500 BTUs are removed from 50lbs of water at 60°F. what is the final water temperature? - Answer: 50°F When operating a refrigeration machine condenser using R-22 refrigerant, under normal conditions the operator observes that the cooling water is being supplied at 85°F and leaving at 95° F. Given this information, the corresponding compressor head pressure in psi should be most nearly ? - Answer: 213 If you had 38°F in the evaporator, what would your suction pressure be for R22? - Answer: 66 psig A centrifugal pump operates at 92 feet head. the corresponding pressure will be close to ? - Answer: 40 psig to raise 10 lbs of water 1 degree how many btus do you need to add? - Answer: 10 btus are needed to add How many KW for a 4 HP motor are needed to run for 10 hours? - Answer: It would take 53.64 KW In a refrigeration plant, a small induction refrigeration motor is running on AC current. In order for the operator to determine the true power consumption, assuming that if every eligible characteristics have been met, the power consumption is determined by the application of which formula? - Answer: V×A×P volts ×amps× power factor if an electric motor is rewound to cut resistance by 1/2, all other factors being equal, the motor would? - Answer: increase by a factor of 2. In a compressors electrical box one of the hot wires is touching the metal box what is most likely to happen? - Answer: An RMO worker can receive electric shock if the touch it. a bimetal disk or klixon is used to? - Answer: protect the wiring and components against excessive current draw. A rectifier converts? - Answer: AC to DC voltage an electric motor that is rated at 3 HP will use how many phases? - Answer: 3 phase power An operator suspects that a shorted motor windings have caused the motor overload to trip. In order to investigate this condition the operator would most likely ? - Answer: use an ohmmeter If a compressor motor went out on an overload, the meter the engineer would use to check the overload would be? - Answer: An ohmmeter If you had to install a solenoid valve to a system which uses 110 volts and needed to convert it to 24 volts, what would you use? - Answer: step down transformer a watt meter requires how many connections? - Answer: four connections, one reading is for voltage (2 connections) and the other is for current (2 connections) A watt meter takes 1 reading using how many leads? - Answer: 4 leads 2 for volts and 2 for amps/current electric devices may be used to provide built in defrosting of refrigerating machine evaporator units. These devices are classified as? - Answer: Resistors..because it generates heat. Capacitors are used in refrigeration motors to? - Answer: store energy for starting and running motors. In an electrical box, you have 3 wires and 2 are insulated and capped, the other wire would be used as a? - Answer: ground wire and insulated. if you have 3 line cable supplying energy to your equipment, and only two lines have fuses, the unfused line would be the ? - Answer: neutral line of a 120/240 circuit. what will energize the solenoid valve in a reciprocating chilled water system? - Answer: The chilled water return from the conditioned space from the thermostat will energize the solenoid valve. where are FLOW switches located? - Answer: on inlet and outlet of chilled water system. what device would be used to vary the capacity of a refrigerating compressor? - Answer: the solenoid valve unloaders Machine room safety standards have been established by? - Answer: ASHRAE 15 What is the most dangerous safety group determined by ASHRAE ? - Answer: B3 Regarding fire safety ANSI/ASHRAE, A1 classification indicates the? - Answer: least flammability and the least toxicity. with respect to the fire safety, the ANSI/ASHRAE refrigerant safety classification that is the most dangerous is? - Answer: A3 Ammonia belongs to which group ? - Answer: 2 B2 safety group The minimum height level inside the machine room exhaust is less than? - Answer: 5' According to the NYC fire code classification of refrigerants, which group does ammonia and sulfur dioxide belong to? - Answer: group 2. Regardless of safety classification of the refrigerant in use. what should the RMO be aware of ? - Answer: Oxygen deprivation Butane requires the approval for use by the ? - Answer: NYC fire Dept. in an emergency if you must dump refrigerant in the sewer, you will dump only when you discharge under the supervision of? - Answer: The fire dept. Any refrigerant containing fluorine or chlorine should Not? - Answer: be dumped The maximum percentage that a refrigerant can be stored in a cylinder is ? - Answer: 75% At the plant where you are employed a refrigerating unit is being taken out of service for major repairs and you have been assigned to withdraw refrigerant for storage in a 40 gallon container. According to the NYC fire law handbook, the maximum quantity of refrigerant in gallons that you may legally fill each container with under any circumstances is? - Answer: 30 According to the safety handbook 45 lbs of refrigerant can be recovered into what size container? - Answer: 60lb When recovering R-22, what color cylinder would you use to store refrigerant in? - Answer: yellow top cylinder The outlet from a fan or duct used to ventilate refrigerants must be ? - Answer: at least 20 feet from any air intake or exhaust or any openings in an adjoining building the refrigeration unit which you have been assigned to is being taken out of service for major repairs. You have been assigned to withdraw refrigerant for storage in suitable containers. According to the NYC fire law handbook you must ensure that containers are approved by ? - Answer: the U.S Department of transportation. As the RMO assigned to the facility you are instructed to store additional refrigerant drawn in the machinery room,during cold weather to eliminate the need for drum warm up prior to recharging the refrigerating unit. If there is a total of 1000 lbs of refrigerant that has been charged to the refrigeration machine, according to the NYC fire law handbook, the maximum quantity in lbs you may legally store in the room is ? - Answer: 200 lbs 20% which systems are the most likely to leak refrigerant in building spaces that are being cooled? - Answer: Direct systems which refrigerant would not be used in an indirect system? - Answer: R-22 one disadvantage in using brines as a cooling medium is corrosion. In commercial practice corrosion and the amount of rust formed is reduced by the addition to the brine solution of? - Answer: Di-chromates An RMO observers a gauge that reads the saturation pressure of a refrigerant. If chilled water is being circulated as a cooling medium, this reading can best be used to ? - Answer: estimate the temperature of the chilled water being pumped to the building spaces that are being cooled Given a refrigeration system which includes a forced draft cooling tower, an economizer and chilled water as the cooling medium, the heat that is removed from the building is finally rejected as ? - Answer: heat of evaporation in the cooling tower if the eliminator plates located below the fan in an induced draft-cooling tower have been clogged, it would most likely result in ? - Answer: An increase in cooling water temperature being returned. the advantage of forced draft over natural draft cooling tower is the ? - Answer: Possiblity of lower water temperature, no dependence on natural wind velocity and the use of a smaller tower size With induced draft cooling tower, what is the lowest temperature attainable? - Answer: dry bulb higher than wet bulb If an outdoor cooling tower is used when there are low outside temperatures what is needed to prevent freezing? - Answer: heater coil When drybulb is 75°F and wetbulb is 75° it results in ? - Answer: 100%RH Because of the latent heat load, the RMO was instructed to start the reciprocating plant for air-conditioning. As far as recommended practice is concerned, the first thing to do is ? - Answer: Turn on chilled water pump, condenser water pumps, start cooling water tower fans. During a hot weekend, an RMO is instructed to start an additional reciprocating machine. The sequence of actions on start up would most likely be? - Answer: Start chiller and condenser water pumps, start cooling water tower fans, check compressor oil levels, check that valves are in the correct position, and turn the machine on. It is possible for chiller water temperature to drop as low as? - Answer: 33°F Refrigerant recycling is an example of? - Answer: inline refrigerant cleaning system which may be used with a centrifugal compressor containing R-123 refrigerant Upon being assigned to a facility during inspection of the facility, you find there has been failure to maintain water treatment. Inspecting the condenser water, the first evidence would most likely be? - Answer: An increase in compressor head pressure During a particular round an operator notices that the suction line and part of the compressor are frosted, the most likely cause of this condition is the ? - Answer: expansion valve open too wide. ( causing more refrigerant to enter flood????) An over charged system can cause ? - Answer: High pressure and evaporator flooding. when operating a refrigeration unit, the operator notices that the motor compressor is short cycling; the unit is using a lowside float valve. The following service requirements would indicate that? - Answer: additional refrigerant should be charged When a compressor is running fine at full flow and you throttle down flow causing the compressor to stop running normal (short cycle), This would happen because of the ? - Answer: Low pressure cutout. When conducting a routine tour of plant operation a RMO observes a significant increase in superheat temperature for the refrigerating fluid entering a reciprocating compressor. The most likely cause for this condition is? - Answer: Scale particles lodged in the TEV valve the disadvantage of having a low head pressure is that? - Answer: the expansion valve will not feed properly While monitoring the operation of a reciprocating refrigeration unit you oversee that the cycling times are normal, compressor compression and temperature are the only reading that are outside the normal rate. Under these conditions service requirements would indicate? - Answer: Inspecting for poor condenser operation/dirty tubes. An RMO is logging readings from a reciprocating compressor refrigeration unit. The crankcase and compressor discharge temperature have significantly dropped and the suction line pressure is high. what may cause this condition is an? - Answer: Expansion valve which is open too wide. An RMO notices excessive cycling of the temperature control for a reciprocating compressor refrigeration unit. The crankcase temperature is high and the compressor discharge temperature is low and the suction line is high, with these set of conditions what would cause this? - Answer: Faulty compressor valves A hermetic compressor is operating with low refrigerant charge. The most likely effect this condition would have on the compressor is it ? - Answer: would operate at a higher temperature. An RMO notices a knocking reciprocating compressor. The RMO is assured the compressor has no worn parts. the most probable cause of this would be? - Answer: Liquid slugging in the compressor Assuming all conditions remain constant, the HP per ton of refrigerating effect would most likely decrease as the? - Answer: suction pressure increases Removing insulation on the suction line, with the engine room temperature at 85°F will cause? - Answer: excessive superheat will occur. a low pressure refrigeration system has a pinhole in the evaporator. the most likely result is ? - Answer: high head pressure Bubbles in the sight glass are most likely cause by a ? - Answer: partially plugged Filter drier liquid level gauge glasses except bulls eye type shall have? - Answer: Shut off valves that are manual and automatic 20 psig would equal about? - Answer: 70 "HG absolute You can't use a flare fitting 3/4 or a larger because? - Answer: it can't tighten to get a good seal For systems containing 50lbs of refrigerant stop valves are required at? - Answer: inlet of each compressor the amount of ventilation for refrigerant removal purposes in a machine room shall be sized according to? - Answer: The amount of refrigerant in the largest machine. You are a RMO and you want to work on the machines pressure relief valve on a dual pressure relief valve system. what valve would you install to be able to work on one pressure relief valve while allowing the other one to operate? - Answer: the three way valve is the valve you would install. what valve is connected to the outlet of the condenser to maintain a constant condenser pressure? - Answer: a water regulating valve You are an RMO and you start the machine and the machine doesn't start. Your fuses, circuit breakers and electrical components are all good. what would you check next? - Answer: check low pressure cutout, pressure switch next superheated vapor is ? - Answer: dry vapor above its boiling point The solenoid valve works by ? - Answer: Opening a plunger and allowing refrigerant in. On a valve plate, the suction valves are on the________________ and the discharge valves are on the _____. - Answer: suction on bottom, discharge on top Glycol is better than brine such as sodium chloride because it? - Answer: causes no corrosion Filter driers remove? - Answer: particles, moisture, and acid A safety head is a ? - Answer: Valve plate being held down with a spring When water turns to ice which latent heat takes place? - Answer: latent heat of fusion An oil separator returns oil to the? - Answer: Crankcase If refrigeration oil is measured to have viscosity and the viscosity number is low, it means? - Answer: It flows easily and smoothly. If you need to add another pump online, you would? - Answer: Open suction side valve and put discharge valve in the throttle position. The automatic expansion valve (aev) is used instead of a tev. It maintains constant pressure on the evaporator. Another function it has on water type evaporators is? - Answer: freezing will not occur. The order of components on the liquid line of a reciprocating system from the king valve is? - Answer: filter drier, solenoid valve, sight glass, and TEV to the evaporator. The unit used to measure the amount of electrons flowing past a certain point in a electrical circuit is called an? - Answer: ampere. Before using a voltmeter, the Technician should always set the range selector to a setting ? - Answer: higher than the voltage expected to be read. As an RMO you enter a system of a reciprocating refrigeration unit. the system has a 150 charge; you would expect to find stop valves on? - Answer: The inlet line on the condenser recieving. Regardless of safety classification of the refrigerant in use, in the event of refrigerant escape, The RMO should be aware of? - Answer: Oxygen deprivation When you are finished leak testing with nitrogen and R-22, the next step would be to? - Answer: Vent Refrigerant and nitrogen into the open air. When oil leaves the sump in a centrifugal refrigeration system, the oil - Answer: travels back to the oil sump after leaving the bearings. The pressure of R-22 at 42°F is? - Answer: 70 psig Flow switches are located in? - Answer: The chilled water and condenser water lines Outdoor cooling towers used during cold seasons require? - Answer: Heaters An intercleaning system can be used on a - Answer: Centrifugal system using R-123 refrigerant. Cooling towers require chemicals to reduce? - Answer: The formation of scale and algae If the chemical treatment would be temporarily unavailable, you would change the bleeding setting of the tower water so? - Answer: more bleeding would take place. An electrical wiring schematic diagram shows? - Answer: The path of electricity in a circuit. 1000 btus of heat is added to 100 lbs of water. the temperature of the water will increase by ? - Answer: 10°F how many btus does it take to melt 5,000 lbs of ice at 0°F and produce 50°F? - Answer: 890,000 BTUs how many BTUS to absorb 5 tons of ice? - Answer: 1,440,000 btus A motor pulley has a diameter of 3" and runs at 1,400 rpms. The fan pulley has a diameter of 5 1/4", the fan pulley will revolve at? - Answer: 800 RPMS If a reciprocating refrigeration compressor cylinder has a 10" bore and 14"stroke, the volume of ref6in cubic inches would be closest to? - Answer: 1,100 cubic inches An atmospheric relief valve can lift from ? - Answer: dirty tubes,low water flow, and hole in tubes The purpose of a gland steam is to create a ? - Answer: positive pressure to eliminate leakage at the end of the shaft The purpose of the jet ejector is to create a - Answer: vacuum for the steam exhaust it takes about how long to warm up a steam turbine? - Answer: 15-20 minutes. The auxiliary oil pump is used during? - Answer: startup? The overspeed trip is a gimble valve that will stop ? - Answer: turbine in the event of the RPMs reaching over the maximum speed a tachometeris used to track ? - Answer: speed of a steam turbine the governor is for? - Answer: automatic speed control the level control in the surface condenser will control? - Answer: recirculation valve Aside from venting refrigerant from your hose connections, never? - Answer: discharge refrigerant. The maximum total amount of refrigerant you can store in the machinery room apart from your refrigerant in your machine is - Answer: 300lbs or 20% Ventilation in the machine room depends on the amount of ? - Answer: refrigerant in the machine the center port of the gauge manifold can be connected to a ? - Answer: recovery machine, charging cylinder or vacuum pump the suction service valve on a reciprocating machine is fronseated. You have evacuated down to 25"HG. You shut the vacuum pump off and low side pressure rises immediately. the cause of rising pressure is a? - Answer: faulty compressor suction valve. the cascade system is needed to obtain? - Answer: low temperatures. The strength of the strong liquor in the absorber of an absorption system ____________ as the evaporator load decreases. - Answer: decreases In an ammonia absorption system the analyzer is located between the? - Answer: generator and rectifier The true power consumed by an induction motor can best be described by the formula:? - Answer: current×voltage×power factor amps×volts ×watts The over speed trip is a gimble safety valve to stop the turbine in the event of the rpms reaching over ? - Answer: the maximum speed Wearing rings are used to? - Answer: prevent wearing on impeller and casing. It also increases efficiency by decreasing the tolerance between the impeller and casing. The main disadvantage of the suction line filter-drier compared to the liquid line filter-drier is? - Answer: If it gets clogged the suction line filter-drier reduces the capacity of the compressor more than the liquid line filter-drier.