3018743
Pregunta 1
Pregunta
Because 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:
Respuesta
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Turn on chilled water pumps and open the bypass to lighten the load
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Install larger fuse to take the initial load and then turn on the cooling tower fans
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Turn on chilled water pump, condenser water pumps and cooling tower fans
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Set thermostat a few degrees higher
Pregunta 2
Pregunta
The most important reason to use 2 compressors in a cascade system is to :
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Accomplish lower temperature
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Permit the use of inexpensive lubrication oil
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Avoid the need for very high compression ratios
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Divide the cooling load between 2 compressors
Pregunta 3
Pregunta
The advantage of forced draft over natural draft cooling tower is
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The possibility of lower water out temp
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There is no dependence on natural wind velocity
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Use of a smaller tower size
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All of the Above
Pregunta 4
Pregunta
what is 29.92" HG in Kpa
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101.3
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101.28
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101.26
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103.2
Pregunta 5
Pregunta
The rupture disk is always piped into the
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High side
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Low side
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Either side of the system
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Neither side of the system
Pregunta 6
Pregunta
A fusible plug melts at
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450 F
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280 F
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212 F
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800 F
Pregunta 7
Pregunta
When will the BTUs absorbed by the condensing water be the greatest?
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Low cond temp, low cond water temp
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High cond temp, High cond water temp
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High Cond temp, Low Cond water temp
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Low Cond temp, High Cond water temp
Pregunta 8
Pregunta
Flooded Evaporators have high heat transfer per square foot, What may be a disadvantage?
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Requires a smaller charge
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Requires a larger charge
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Requires the use of a TXV for proper feed
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Water has to be drained daily
Pregunta 9
Pregunta
Shell and tube condensers have the advantage of
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Removing heads for cleaning the water sides of the tubes
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The refrigerant connections do not have to be disrupted
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Using acid for cleaning
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Both A and B are correct
Pregunta 10
Pregunta
Shell and coil condensers have the advantage of
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Removing the heads for cleaning the water sides of the tubes
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The refrigerant connections do not have to be disrupted
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Has less of a chance of developing leaks
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Both A and B are correct
Pregunta 11
Pregunta
How many BTUs would be removed in a 30 ton system?
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12,000 per hour
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360,000 per minute
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12,000 per minute
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360,000 per hour
Pregunta 12
Pregunta
If you have 62 psi at 35 F and 70 psi at 45 deg F, what would 38 deg F be?
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66
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64.4
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65
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62
Pregunta 13
Pregunta
Copper is used in refrigeration systems, like in heat ex-changers because?
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Easy fabrication
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Easy durability
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High thermal conductivity
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Flexability
Pregunta 14
Pregunta
The accessories on the liquid line are in what order?
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solenoid valve, drier, and sightglass
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receiver, drier, solenoid valve, and sightglass
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muffler, drier, sightglass, and solenoid valve
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accumulator, muffler, drier, sightglass
Pregunta 15
Pregunta
A condenser is 20' long and 6' in diameter, what is the volume in gallons if 7.48 gallons is 1 cu/ft?
Respuesta
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565
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4227
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1808
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1205
Pregunta 16
Pregunta
If the low pressure cutout cycles the compressor off, what starts the compressor again?
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Solenoid valve
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High pressure cut out
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Low pressure cut out
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Thermostat
Pregunta 17
Pregunta
Removing insulation on the suction line with the engine room temp at 85F, what will occur?
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Flooded evaporator
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Starved evaporator
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Excessive superheat
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Low superheat
Pregunta 18
Pregunta
If you were running three compressors, which best describes the state of refrigerant leaving the third evaporator coil?
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Mostly liquid, some vapor
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Mostly vapor, some liquid
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Superheated vapor
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Highly superheated vapor
Pregunta 19
Pregunta
An electric motor that is rated at 3 HP will?
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Use three phase
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Need a capacitor
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Use a single Phase
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Will run with reduced power output
Pregunta 20
Pregunta
In a 3 stage centrifugal chiller, what happens to the pressure as it reaches the final stage?
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Increases
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Decreases
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Speed changes not pressure
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Volume changes not the pressure
Pregunta 21
Pregunta
With an induced draft cooling tower, what is the lowest temperature attainable for a cooling tower?
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Wet bulb equal to dry bulb
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Dry bulb slightly lower than wet bulb
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Dry bulb higher than wet bulb
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Wet bulb can never be lower than dry bulb
Pregunta 22
Pregunta
When 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?
Respuesta
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Dirty filter/ strainer
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Air getting in seals
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Low pressure cut out
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High head pressure
Pregunta 23
Pregunta
When dry bulb is 75F and wet bulb is 75F?
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Not possible
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Very low humidity
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Thermometer is defective
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100% relative humidity
Pregunta 24
Pregunta
When a compressor is said to have a safety head this means :
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Compressor operates with normal pressures
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Compressor operates with low pressures
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Compressor has a pressure relief device
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Compressor has high pressure cut out
Pregunta 25
Pregunta
The cylinder unloader controls capacity, is there any other function it may have?
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Assist with compressor shut down
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Assist with compressor start up
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There is no other function
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Releases pressure for protection
Pregunta 26
Pregunta
An 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 :
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Capacitor
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Voltmeter
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Ohmeter
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Ammeter
Pregunta 27
Pregunta
When recovering R22, What color would the cylinder be that you are storing the refrigerant in?
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Yellow tops
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White tops
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Green tops
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Gray tops
Pregunta 28
Pregunta
If unloaders were to fail in the unloaded position, what happens in a system using reciprocating compressor?
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The evaporator will starve
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Cause high superheat
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Not enough refrigerant to coil
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All of the above
Pregunta 29
Pregunta
When the temperature and the load increase and you need to add another pump online, you would :
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Close both suction and discharge
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Open both suction and discharge
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Open suction and throttle discharge
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Open discharge bypass and close suction
Pregunta 30
Pregunta
When a system does not have unloaders, what is needed?
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Other capacity control
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Variable inlet guide vanes
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An economizer
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Solenoid on liquid line
Pregunta 31
Pregunta
When an evaporator is not equipped with an equalizer line, you would most likely find
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Feeder bulb placed in different area
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A distributor
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An automatic expansion valve
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Both high and low side pressures identical
Pregunta 32
Pregunta
When you plan on overhauling a system and you have recovered all liquid refrigerant, what is next?
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Go ahead and do the work
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Recover all vapor, then do the work
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Send liquid nitrogen through
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Evacuate system
Pregunta 33
Pregunta
When there is a 5lb pressure drop across evaporator, you need an external equalizing line, what happens if it disconnects?
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Excessive superheat
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Evaporator would starve
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Evaporator would flood
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TEV would not function
Pregunta 34
Pregunta
The metering device used in a condenser is a high side float, this device will :
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Control the amount of water in condenser
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Control the amount of refrigerant in condenser
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Keeps a constant pressure
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Keeps a constant temperature
Pregunta 35
Pregunta
If a low side float is being used :
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Pressure will be constant
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It will control refrigerant flow
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It will control water flow
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Temperature is constant
Pregunta 36
Pregunta
The heat that boils off in a condenser is :
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Latent heat
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Sensible heat
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Superheat
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All of the above
Pregunta 37
Pregunta
The condenser that uses air and water for cooling is the :
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Air cooled
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Water cooled
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Evaporative
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Both a and b are correct
Pregunta 38
Pregunta
A hermetic compressor is operating with a low refrigerant charge, What is the most likely effect this condition would have on the compressor?
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Head pressure would rise
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Compressor would operate at higher temperature
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Have no effect on the compressor
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Oil pressure would rise
Pregunta 39
Pregunta
A centrifugal chiller has a suction pressure of 18" Hg vacuum and discharge pressure of 6 psig. What is the compression ratio of this unit ?
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3.50
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2.96
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1.75
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2.76
Pregunta 40
Pregunta
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?
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Step up transformer
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Step down transformer
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AC to DC rectifier
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Rewire circuit with smaller gauge wire
Pregunta 41
Pregunta
If you had 38 degrees in the evaporator, what should you suction pressure be for R22?
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66 Psia
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66 Psig
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76 Psig
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76 Psia
Pregunta 42
Pregunta
An oil with low viscosity would :
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Not be used for refrigeration
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Be used for engine/motors
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Be used for air conditioning
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Both B and C are correct
Pregunta 43
Pregunta
When charging a centrifugal system the position of the valve is :
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Front seated
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Back seated
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Cracked off the back seat
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Closed
Pregunta 44
Pregunta
The suction and discharge valves in a reciprocating compressor are positioned :
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Over valve plate
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Under valve plate
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Both under and over valve plate
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None of the above
Pregunta 45
Pregunta
What refrigerants are you not able to dump?
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CFC
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HCFC
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HFC
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Any refrigerant containing chlorine or flourine
Pregunta 46
Pregunta
There 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?
Respuesta
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High head pressure
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Low suction pressure
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Water valve stuck open
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Water valve stuck closed
Pregunta 47
Pregunta
How low can chiller water temperature be?
Respuesta
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32 degrees F
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33 degrees F
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38 degrees F
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42 degrees F
Pregunta 48
Pregunta
While using a halide torch to check for refrigerant leaks, if the flame was to turn yellow, what happened?
Respuesta
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Container is empty
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Restriction in tube
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Refrigerant is leaking
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Refrigerant has high moisture content
Pregunta 49
Pregunta
What is the cubic feet of a 20' long 6' vessel on the evaporator?
Respuesta
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120 cubic feet
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565 cubic feet
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4,235 cubic feet
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4,710 cubic feet
Pregunta 50
Pregunta
A water regulating valve is installed in a water cooled condenser. The operating force on this valve is respondent to :
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High side pressure
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Chilled water temperature
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Circulating water pressure through the condenser
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Manual operation
Pregunta 51
Pregunta
Compound gauges can measure:
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Above atmospheric
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Below atmospheric
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Temperature
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All of the above
Pregunta 52
Pregunta
A low pressure refrigeration system has a pin hole in the evaporator. What is the most likely result?
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High head pressure
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Frost around leak area
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High condenser water pressure
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Low condenser water pressure
Pregunta 53
Pregunta
What does the centrifugal compressor generate inside?
Respuesta
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High pressure, low velocity
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High volume, low pressure
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Low velocity, Low pressure
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High velocity, high pressure
Pregunta 54
Pregunta
Oil flashpoint temperature in the compressor should be :
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Lower than the heat of compression
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Higher than the heat of compression
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Equal to the heat of compression
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Equal to the heat absorbed
Pregunta 55
Pregunta
Compressor motors that operate inside the refrigerant atmosphere (atmospheric) :
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Must use materials compatible with the system refrigerants
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Motors must be assembled in clean atmosphere and kept dry
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Are not worked on in the field
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All of the above
Pregunta 56
Pregunta
In a centrifugal three stage compressor:
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Pressure increases with each stage
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Impellers are same size
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Impellers increase with each stage
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Both A and B are correct
Pregunta 57
Pregunta
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 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 :
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Lubricating the pump
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After having bled air from the pump casing petcock
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Starting an additional pump
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Shutting the pump down
Pregunta 58
Pregunta
In relation to the suction pressure of a compressor, The reading in the oil pressure gauge should read :
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15-30 psi lower
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60-90 psi higher
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15-30 psi higher
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30-60 psi lower
Pregunta 59
Pregunta
The following most accurate statement regarding compressor motors that run in a refrigerant atmosphere is that they :
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May use internal rubber cushions
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May be repaired on site when they malfunction
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Use materials tailored to the refigerant
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Use same materials as a pump in air
Pregunta 60
Pregunta
The following is an example of an "inline" refrigerant cleaning system which may be used with a centrifugal compressor containing R123 refrigerant is :
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Refrigerant recovery
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Refrigerant disposal
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Refrigerant reclaiming
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Refrigerant recycling
Pregunta 61
Pregunta
Regarding fire safety ANSI/ASHRAE, which classification indicates the latest flammability and least toxicity?
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A1
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B2
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A2
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B1
Pregunta 62
Pregunta
Bubbles in the sight glass are most likely caused by :
Respuesta
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An overcharged system
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Non-condensable gases
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Light load on the plant
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Partially plugged filter/drier
Pregunta 63
Pregunta
In addition to regulating the refrigerant flow according to the needs of the system, metering devices also serve to :
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Increase compressor capacity
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Hold system to a constant load
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Restrict flow of refrigerant from the high side to low side
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Shed load as load increases
Pregunta 64
Pregunta
Regardless of safety classification of the refrigerant in use, in the event of refrigerant escape, the RMO should be aware of :
Respuesta
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A refrigerant fire
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Refrigerant poisioning
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Oxygen deprivation
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Atmospheric superheating
Pregunta 65
Pregunta
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 :
Respuesta
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Are approved by the US department of transportation
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Are approved by the facilities manager
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Do not weigh more than 200lbs when filled
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Do not exceed 55 gallon capacity
Pregunta 66
Pregunta
An 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 :
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Malfunctioning of the water makeup float valve
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Too much time in between pump servicing
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Operating at sustained high loads
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Lowering the chilled water temperature
Pregunta 67
Pregunta
An 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:
Respuesta
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Compressor cycling
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An expansion valve which is closed too much
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An expansion valve which is open too wide
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Faulty compressor valves
Pregunta 68
Pregunta
The Ratio of actual pressure of water vapor in the atmosphere to the saturation pressure / temp is called :
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Absolute humidity
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Humidity effect
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Partial pressue
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Relative humidity
Pregunta 69
Pregunta
The dividing line between the high and low sides of the refrigeration system is :
Respuesta
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The connection between the compressor and condenser
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Needle valve mechanism
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Compressor outlet and the orifice of the metering device
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Center plate of the refrigeration mechanism
Pregunta 70
Pregunta
An 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:
Respuesta
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Air leaks through the pump packing
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Operating at sustained high loads
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Faulty cooling tower water level controller
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Too long a period between pump servicing
Pregunta 71
Pregunta
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:
Respuesta
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Water hammer
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Clogged strainer in pump inlet
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Poor bearing lubrication
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Air leaks in the pump
Pregunta 72
Pregunta
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 :
Respuesta
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Show the least benefit for descaling tubes at high water velocity
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Increase with the velocity of water in the tubes
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Increase with lower log mean temperature difference
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Show only a small increase if the tubes are descaled
Pregunta 73
Pregunta
Electric devices may be used to provide built in defrosting of refrigeration machine evaporator units. These devices are classified as:
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Relays
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Induction coils
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Capacitors
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Resistors
Pregunta 74
Pregunta
Latent 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 :
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Heat required to cool the refrigerant from compressor discharge to evaporative temp is subtracted from the latent heat
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Refrigerant latent heat is divided by specific gravity of the refrigerant
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Refrigerant critical temperature is factored into the calculation of the refrigerating effect
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Refrigerant latent heat is divided by the refrigerant circulation rate
Pregunta 75
Pregunta
Superheated 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:
Respuesta
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Non-condensables are more prone to collect in the system
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Frost may develop in the suction line
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It will decrease the capacity of the compressor and the refrigeration machine
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The compressor head pressure drops too low
Pregunta 76
Pregunta
An operator observes a reading of 60c on a refrigerating unit. The same reading in F scale would be closer to: (x1.8+32)
Respuesta
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140
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185
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155
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170
Pregunta 77
Pregunta
What is the state of refrigerant as it leaves the compressor and as it leaves the condenser:
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Superheated vapor and superheated liquid
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Superheated vapor and warm subcooled liquid
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Saturated Vapor and cold sub cooled liquid
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Saturated vapor and warm sub cooled liquid
Pregunta 78
Pregunta
Clearance volume:
Respuesta
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Affects compressor capacity
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Is the space that traps liquid refrigerant
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Varies, depending on compressor speed
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Is the same on all compressors
Pregunta 79
Pregunta
A 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:
Respuesta
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Adequate superheat
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Starved evaporator
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Excessive superheat
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Flooded Evaporator
Pregunta 80
Pregunta
Of the following one of the primary reasons for the insulation of a crankcase breather line is :
Respuesta
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Increase the compressor efficency
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To prevent oil slugging in the compressor
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Keep the shaft packing lubricated
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To prevent refrigerant from entering the compressor suction
Pregunta 81
Pregunta
A 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:
Respuesta
-
Purge unit operation
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An expansion valve that is open too wide
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Faulty compressor valves
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Condenser operation, dirty tubes, or cooling water control
Pregunta 82
Pregunta
A reciprocating system using an evaporative condenser, the muffler is installed between:
Respuesta
-
Evaporator and Compressor
-
Receiver and expansion valve
-
Compressor and evaporative condenser
-
Receiver and condenser
Pregunta 83
Pregunta
While operating an R12 reciprocating system, the RMO noticed the oil foaming the in the crankcase. This condition most likely would have been caused by:
Respuesta
-
Addition of liquid freon
-
Sudden drop in oil Temp
-
Sudden drop in crankcase pressure
-
Addition of oil to the crankcase
Pregunta 84
Pregunta
Assume 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:
Respuesta
-
All valve plates, springs and some valve seats
-
All valve and valve seats
-
Valve seats only
-
Suction Valves only
Pregunta 85
Pregunta
During a hot weekend, RMO is instructed to start additional reciprocating machine. The sequence of actions on startup would most likely be:
Respuesta
-
check compressor oil, start cooling towers, check valves are in correct position, turn on machine, start chiller and condenser water pumps
-
start chiller and condenser water pumps, start cooling water tower fans, check compressor oil levels, check that valves are in correct position, turn machine on
-
turn machine on, check valves are in correct position, start tower fans, check compressor oil levels, start chiller and condenser water pumps
-
check valves are in correct position, start cooling water tower fans, start machine, start chiller and condenser water pumps, check compressor oil levels
Pregunta 86
Pregunta
While doing a routine inspection, the RMO noticed the bulb of the TEV on the floor, the operator should attach the bulb at:
Respuesta
-
center of the coil
-
expansion valve outlet
-
end of coil
-
3/4 away towards the end of the coil
Pregunta 87
Pregunta
When 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:
Respuesta
-
Put more grease on the remaining belts
-
Replace all 4 belts with a new set
-
Replace the broken belt only
-
Operate with the remaining 3 belts
Pregunta 88
Pregunta
An 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 :
Respuesta
-
18
-
14
-
20
-
30.3
Pregunta 89
Pregunta
What is the maximum percentage that a refrigerant can be stored in a cylinder?
Respuesta
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75%
-
80%
-
90%
-
100%
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