Test
RMO Exam
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Preguntas del test (89)
1Because of the latent heat load, refrigeration machine operator was instructed to start the reciprocating plant for air conditioning. Of the following according to recommended practice, the first thing to do is:
- ATurn on chilled water pumps and open the bypass to lighten the load
- BInstall larger fuse to take the initial load and then turn on the cooling tower fans
- CTurn on chilled water pump, condenser water pumps and cooling tower fans
- DSet thermostat a few degrees higher
2The most important reason to use 2 compressors in a cascade system is to :
- AAccomplish lower temperature
- BPermit the use of inexpensive lubrication oil
- CAvoid the need for very high compression ratios
- DDivide the cooling load between 2 compressors
3The advantage of forced draft over natural draft cooling tower is
- AThe possibility of lower water out temp
- BThere is no dependence on natural wind velocity
- CUse of a smaller tower size
- DAll of the Above
4what is 29.92" HG in Kpa
- A101.3
- B101.28
- C101.26
- D103.2
5The rupture disk is always piped into the
- AHigh side
- BLow side
- CEither side of the system
- DNeither side of the system
6A fusible plug melts at
- A450 F
- B280 F
- C212 F
- D800 F
7When will the BTUs absorbed by the condensing water be the greatest?
- ALow cond temp, low cond water temp
- BHigh cond temp, High cond water temp
- CHigh Cond temp, Low Cond water temp
- DLow Cond temp, High Cond water temp
8Flooded Evaporators have high heat transfer per square foot, What may be a disadvantage?
- ARequires a smaller charge
- BRequires a larger charge
- CRequires the use of a TXV for proper feed
- DWater has to be drained daily
9Shell and tube condensers have the advantage of
- ARemoving heads for cleaning the water sides of the tubes
- BThe refrigerant connections do not have to be disrupted
- CUsing acid for cleaning
- DBoth A and B are correct
10Shell and coil condensers have the advantage of
- ARemoving the heads for cleaning the water sides of the tubes
- BThe refrigerant connections do not have to be disrupted
- CHas less of a chance of developing leaks
- DBoth A and B are correct
11How many BTUs would be removed in a 30 ton system?
- A12,000 per hour
- B360,000 per minute
- C12,000 per minute
- D360,000 per hour
12If you have 62 psi at 35 F and 70 psi at 45 deg F, what would 38 deg F be?
- A66
- B64.4
- C65
- D62
13Copper is used in refrigeration systems, like in heat ex-changers because?
- AEasy fabrication
- BEasy durability
- CHigh thermal conductivity
- DFlexability
14The accessories on the liquid line are in what order?
- Asolenoid valve, drier, and sightglass
- Breceiver, drier, solenoid valve, and sightglass
- Cmuffler, drier, sightglass, and solenoid valve
- Daccumulator, muffler, drier, sightglass
15A condenser is 20' long and 6' in diameter, what is the volume in gallons if 7.48 gallons is 1 cu/ft?
- A565
- B4227
- C1808
- D1205
16If the low pressure cutout cycles the compressor off, what starts the compressor again?
- ASolenoid valve
- BHigh pressure cut out
- CLow pressure cut out
- DThermostat
17Removing insulation on the suction line with the engine room temp at 85F, what will occur?
- AFlooded evaporator
- BStarved evaporator
- CExcessive superheat
- DLow superheat
18If you were running three compressors, which best describes the state of refrigerant leaving the third evaporator coil?
- AMostly liquid, some vapor
- BMostly vapor, some liquid
- CSuperheated vapor
- DHighly superheated vapor
19An electric motor that is rated at 3 HP will?
- AUse three phase
- BNeed a capacitor
- CUse a single Phase
- DWill run with reduced power output
20In a 3 stage centrifugal chiller, what happens to the pressure as it reaches the final stage?
- AIncreases
- BDecreases
- CSpeed changes not pressure
- DVolume changes not the pressure
21With an induced draft cooling tower, what is the lowest temperature attainable for a cooling tower?
- AWet bulb equal to dry bulb
- BDry bulb slightly lower than wet bulb
- CDry bulb higher than wet bulb
- DWet bulb can never be lower than dry bulb
22When a compressor is running fine at full flow and you throttle down flow causing the compressor to stop running normal (short cycle), why would this happen?
- ADirty filter/ strainer
- BAir getting in seals
- CLow pressure cut out
- DHigh head pressure
23When dry bulb is 75F and wet bulb is 75F?
- ANot possible
- BVery low humidity
- CThermometer is defective
- D100% relative humidity
24When a compressor is said to have a safety head this means :
- ACompressor operates with normal pressures
- BCompressor operates with low pressures
- CCompressor has a pressure relief device
- DCompressor has high pressure cut out
25The cylinder unloader controls capacity, is there any other function it may have?
- AAssist with compressor shut down
- BAssist with compressor start up
- CThere is no other function
- DReleases pressure for protection
26An operator suspects that shorted motor windings have caused the motor overloads to trip. In order to investigate this condition, the operator would be most correct to use :
- ACapacitor
- BVoltmeter
- COhmeter
- DAmmeter
27When recovering R22, What color would the cylinder be that you are storing the refrigerant in?
- AYellow tops
- BWhite tops
- CGreen tops
- DGray tops
28If unloaders were to fail in the unloaded position, what happens in a system using reciprocating compressor?
- AThe evaporator will starve
- BCause high superheat
- CNot enough refrigerant to coil
- DAll of the above
29When the temperature and the load increase and you need to add another pump online, you would :
- AClose both suction and discharge
- BOpen both suction and discharge
- COpen suction and throttle discharge
- DOpen discharge bypass and close suction
30When a system does not have unloaders, what is needed?
- AOther capacity control
- BVariable inlet guide vanes
- CAn economizer
- DSolenoid on liquid line
31When an evaporator is not equipped with an equalizer line, you would most likely find
- AFeeder bulb placed in different area
- BA distributor
- CAn automatic expansion valve
- DBoth high and low side pressures identical
32When you plan on overhauling a system and you have recovered all liquid refrigerant, what is next?
- AGo ahead and do the work
- BRecover all vapor, then do the work
- CSend liquid nitrogen through
- DEvacuate system
33When there is a 5lb pressure drop across evaporator, you need an external equalizing line, what happens if it disconnects?
- AExcessive superheat
- BEvaporator would starve
- CEvaporator would flood
- DTEV would not function
34The metering device used in a condenser is a high side float, this device will :
- AControl the amount of water in condenser
- BControl the amount of refrigerant in condenser
- CKeeps a constant pressure
- DKeeps a constant temperature
35If a low side float is being used :
- APressure will be constant
- BIt will control refrigerant flow
- CIt will control water flow
- DTemperature is constant
36The heat that boils off in a condenser is :
- ALatent heat
- BSensible heat
- CSuperheat
- DAll of the above
37The condenser that uses air and water for cooling is the :
- AAir cooled
- BWater cooled
- CEvaporative
- DBoth a and b are correct
38A hermetic compressor is operating with a low refrigerant charge, What is the most likely effect this condition would have on the compressor?
- AHead pressure would rise
- BCompressor would operate at higher temperature
- CHave no effect on the compressor
- DOil pressure would rise
39A centrifugal chiller has a suction pressure of 18" Hg vacuum and discharge pressure of 6 psig. What is the compression ratio of this unit ?
- A3.50
- B2.96
- C1.75
- D2.76
40If 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?
- AStep up transformer
- BStep down transformer
- CAC to DC rectifier
- DRewire circuit with smaller gauge wire
41If you had 38 degrees in the evaporator, what should you suction pressure be for R22?
- A66 Psia
- B66 Psig
- C76 Psig
- D76 Psia
42An oil with low viscosity would :
- ANot be used for refrigeration
- BBe used for engine/motors
- CBe used for air conditioning
- DBoth B and C are correct
43When charging a centrifugal system the position of the valve is :
- AFront seated
- BBack seated
- CCracked off the back seat
- DClosed
44The suction and discharge valves in a reciprocating compressor are positioned :
- AOver valve plate
- BUnder valve plate
- CBoth under and over valve plate
- DNone of the above
45What refrigerants are you not able to dump?
- ACFC
- BHCFC
- CHFC
- DAny refrigerant containing chlorine or flourine
46There is an automatic water regulating valve on a reciprocating chiller. Water is entering the condenser at 85F and leaving the condenser at 88F. You know there is no scale and the tubes are not covered with film. What can be causing this condition?
- AHigh head pressure
- BLow suction pressure
- CWater valve stuck open
- DWater valve stuck closed
47How low can chiller water temperature be?
- A32 degrees F
- B33 degrees F
- C38 degrees F
- D42 degrees F
48While using a halide torch to check for refrigerant leaks, if the flame was to turn yellow, what happened?
- AContainer is empty
- BRestriction in tube
- CRefrigerant is leaking
- DRefrigerant has high moisture content
49What is the cubic feet of a 20' long 6' vessel on the evaporator?
- A120 cubic feet
- B565 cubic feet
- C4,235 cubic feet
- D4,710 cubic feet
50A water regulating valve is installed in a water cooled condenser. The operating force on this valve is respondent to :
- AHigh side pressure
- BChilled water temperature
- CCirculating water pressure through the condenser
- DManual operation
51Compound gauges can measure:
- AAbove atmospheric
- BBelow atmospheric
- CTemperature
- DAll of the above
52A low pressure refrigeration system has a pin hole in the evaporator. What is the most likely result?
- AHigh head pressure
- BFrost around leak area
- CHigh condenser water pressure
- DLow condenser water pressure
53What does the centrifugal compressor generate inside?
- AHigh pressure, low velocity
- BHigh volume, low pressure
- CLow velocity, Low pressure
- DHigh velocity, high pressure
54Oil flashpoint temperature in the compressor should be :
- ALower than the heat of compression
- BHigher than the heat of compression
- CEqual to the heat of compression
- DEqual to the heat absorbed
55Compressor motors that operate inside the refrigerant atmosphere (atmospheric) :
- AMust use materials compatible with the system refrigerants
- BMotors must be assembled in clean atmosphere and kept dry
- CAre not worked on in the field
- DAll of the above
56In a centrifugal three stage compressor:
- APressure increases with each stage
- BImpellers are same size
- CImpellers increase with each stage
- DBoth A and B are correct
57An operator suspects that a vertical check valve on a discharge of a centrifugal pump is defective, this is a condenser pump and one of three pumps in parallel. If the suspicion is true and the check valve fails to seat when required, the pump and connecting piping will most likely be damaged when :
- ALubricating the pump
- BAfter having bled air from the pump casing petcock
- CStarting an additional pump
- DShutting the pump down
58In relation to the suction pressure of a compressor, The reading in the oil pressure gauge should read :
- A15-30 psi lower
- B60-90 psi higher
- C15-30 psi higher
- D30-60 psi lower
59The following most accurate statement regarding compressor motors that run in a refrigerant atmosphere is that they :
- AMay use internal rubber cushions
- BMay be repaired on site when they malfunction
- CUse materials tailored to the refigerant
- DUse same materials as a pump in air
60The following is an example of an "inline" refrigerant cleaning system which may be used with a centrifugal compressor containing R123 refrigerant is :
- ARefrigerant recovery
- BRefrigerant disposal
- CRefrigerant reclaiming
- DRefrigerant recycling
61Regarding fire safety ANSI/ASHRAE, which classification indicates the latest flammability and least toxicity?
- AA1
- BB2
- CA2
- DB1
62Bubbles in the sight glass are most likely caused by :
- AAn overcharged system
- BNon-condensable gases
- CLight load on the plant
- DPartially plugged filter/drier
63In addition to regulating the refrigerant flow according to the needs of the system, metering devices also serve to :
- AIncrease compressor capacity
- BHold system to a constant load
- CRestrict flow of refrigerant from the high side to low side
- DShed load as load increases
64Regardless of safety classification of the refrigerant in use, in the event of refrigerant escape, the RMO should be aware of :
- AA refrigerant fire
- BRefrigerant poisioning
- COxygen deprivation
- DAtmospheric superheating
65The 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 :
- AAre approved by the US department of transportation
- BAre approved by the facilities manager
- CDo not weigh more than 200lbs when filled
- DDo not exceed 55 gallon capacity
66An operator confirms that a chiller water pump in a refrigeration system employing R123 is cavitating, of the following, the most likely cause for this condition is :
- AMalfunctioning of the water makeup float valve
- BToo much time in between pump servicing
- COperating at sustained high loads
- DLowering the chilled water temperature
67An RMO is logging readings from a reciprocating compressor-refrigerating unit. The crankcase and compressor discharge temp have dropped significantly and suction line pressure is high. Of the following the one that may cause this set of conditions is:
- ACompressor cycling
- BAn expansion valve which is closed too much
- CAn expansion valve which is open too wide
- DFaulty compressor valves
68The Ratio of actual pressure of water vapor in the atmosphere to the saturation pressure / temp is called :
- AAbsolute humidity
- BHumidity effect
- CPartial pressue
- DRelative humidity
69The dividing line between the high and low sides of the refrigeration system is :
- AThe connection between the compressor and condenser
- BNeedle valve mechanism
- CCompressor outlet and the orifice of the metering device
- DCenter plate of the refrigeration mechanism
70An RMO verifies that a condenser water pump is cavitating in a refrigeration system employing R22 refrigerant. Of the following the most likely cause for this condition is:
- AAir leaks through the pump packing
- BOperating at sustained high loads
- CFaulty cooling tower water level controller
- DToo long a period between pump servicing
71An 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:
- AWater hammer
- BClogged strainer in pump inlet
- CPoor bearing lubrication
- DAir leaks in the pump
72Assuming 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 :
- AShow the least benefit for descaling tubes at high water velocity
- BIncrease with the velocity of water in the tubes
- CIncrease with lower log mean temperature difference
- DShow only a small increase if the tubes are descaled
73Electric devices may be used to provide built in defrosting of refrigeration machine evaporator units. These devices are classified as:
- ARelays
- BInduction coils
- CCapacitors
- DResistors
74Latent heat and refrigeration effect are usually listed as refrigerant properties. The refrigerating effect is also always a lower value than the latent heat because the :
- AHeat required to cool the refrigerant from compressor discharge to evaporative temp is subtracted from the latent heat
- BRefrigerant latent heat is divided by specific gravity of the refrigerant
- CRefrigerant critical temperature is factored into the calculation of the refrigerating effect
- DRefrigerant latent heat is divided by the refrigerant circulation rate
75Superheated vapor flowing into a reciprocating compressor protects the compressor parts against liquid intake. Of the following, one of the problems associated with superheat is that:
- ANon-condensables are more prone to collect in the system
- BFrost may develop in the suction line
- CIt will decrease the capacity of the compressor and the refrigeration machine
- DThe compressor head pressure drops too low
76An operator observes a reading of 60c on a refrigerating unit. The same reading in F scale would be closer to: (x1.8+32)
- A140
- B185
- C155
- D170
77What is the state of refrigerant as it leaves the compressor and as it leaves the condenser:
- ASuperheated vapor and superheated liquid
- BSuperheated vapor and warm subcooled liquid
- CSaturated Vapor and cold sub cooled liquid
- DSaturated vapor and warm sub cooled liquid
78Clearance volume:
- AAffects compressor capacity
- BIs the space that traps liquid refrigerant
- CVaries, depending on compressor speed
- DIs the same on all compressors
79A Thermal is attached to the suction pipe between the evaporator coil and the compressor covered by an insulating line. Assuming the machine room is 85F unraveling of the insulation would result in:
- AAdequate superheat
- BStarved evaporator
- CExcessive superheat
- DFlooded Evaporator
80Of the following one of the primary reasons for the insulation of a crankcase breather line is :
- AIncrease the compressor efficency
- BTo prevent oil slugging in the compressor
- CKeep the shaft packing lubricated
- DTo prevent refrigerant from entering the compressor suction
81A RMO notices excessive cycling of the temp control for a reciprocating compressor refrigeration unit. The crankcase temp is high, the compressor discharge temp is low and the suction line is high, of the following the one that may be causing this set of conditions is:
- APurge unit operation
- BAn expansion valve that is open too wide
- CFaulty compressor valves
- DCondenser operation, dirty tubes, or cooling water control
82A reciprocating system using an evaporative condenser, the muffler is installed between:
- AEvaporator and Compressor
- BReceiver and expansion valve
- CCompressor and evaporative condenser
- DReceiver and condenser
83While operating an R12 reciprocating system, the RMO noticed the oil foaming the in the crankcase. This condition most likely would have been caused by:
- AAddition of liquid freon
- BSudden drop in oil Temp
- CSudden drop in crankcase pressure
- DAddition of oil to the crankcase
84Assume that a new valve plate has been installed while they are repairing a reciprocating compressor in a refrigeration plant. The installation of a new valve plate will require the replacement of:
- AAll valve plates, springs and some valve seats
- BAll valve and valve seats
- CValve seats only
- DSuction Valves only
85During a hot weekend, RMO is instructed to start additional reciprocating machine. The sequence of actions on startup would most likely be:
- Acheck compressor oil, start cooling towers, check valves are in correct position, turn on machine, start chiller and condenser water pumps
- Bstart chiller and condenser water pumps, start cooling water tower fans, check compressor oil levels, check that valves are in correct position, turn machine on
- Cturn machine on, check valves are in correct position, start tower fans, check compressor oil levels, start chiller and condenser water pumps
- Dcheck valves are in correct position, start cooling water tower fans, start machine, start chiller and condenser water pumps, check compressor oil levels
86While doing a routine inspection, the RMO noticed the bulb of the TEV on the floor, the operator should attach the bulb at:
- Acenter of the coil
- Bexpansion valve outlet
- Cend of coil
- D3/4 away towards the end of the coil
87When operating a reciprocating refrigeration system with a belt driven compressor, an RMO notices that one of the 4 belts is broken. Of the following, the most advisable course of action for the RMO would be to:
- APut more grease on the remaining belts
- BReplace all 4 belts with a new set
- CReplace the broken belt only
- DOperate with the remaining 3 belts
88An operator reads the valve tag on a pressure relief valve and notices that the valve is set to unseat at an evaporator pressure of 15 psi, The corresponding set pressure in inches of HG is :
- A18
- B14
- C20
- D30.3
89What is the maximum percentage that a refrigerant can be stored in a cylinder?
- A75%
- B80%
- C90%
- D100%
Información
- Descripción
- Test sobre RMO Exam , creado por mst915 el 01/07/2015.
- Autor
- mst915
- Idioma
- English
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