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Refrigerant Machine Operator Practical > Refrigerant Machine Operator Certification Practice Test #1 > Flashcards

Refrigerant Machine Operator Certification Practice Test #1 Flashcards

1
Q

The amount of refrigerant that flows through the orifice plate is determined by ____

A. THE NUMBER OF ECONOMIZER STAGES

B. THE NUMBER OF COMPRESSION STAGES

C. TEMPERATURE OF REFRIGERANT IN THE HIGH SIDE

D. DIFFERENCE IN PRESSURE BETWEEN HIGH AND LOW SIDES

A

Difference in pressure between high and low sides

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2
Q

Unloaders are used to

INCREASE CAPACITY

STOP FLOW OF REFRIGERANT WITHOUT STOPPING

REDUCE CAPACITY

START FLOW OF REFRIGERANT THROUGH SYSTEM

A

Reduce capacity

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3
Q

Semi-Hermetic compressors may be better to use than hermetic compressors because hermetic compressors ____

ARE FULLY ENCLOSED AND CANNOT BE SERVICED ON SITE

ARE EASIER TO GET TO

ARE MORE DIFFICULT TO GET TO

ARE MORE EXPENSIVE

A

Are fully enclosed and cannot be serviced on site

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4
Q

When conducting a routine tour of plant operation a RMO observes a significant increase in superheat temp. For the refrigerating fluid entering a reciprocating compressor. The most likely cause for this condition is ____

SCALE PARTICLES LODGED IN THE TEV VALVE

UNRAVELING OF THE INSULATION PROTECTING THE TEV VALVE THERMAL BULB

BUILD-UP OF NONCONDENSABLES IN THE CONDENSER

OVERCHARGE OF REFRIGERANT

A

Scale particles lodged in the TEV valve

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5
Q

A room thermostat controls the liquid line solenoid valve in the commercial refrigeration system. The compressor is activated by ____

THE HIGH PRESSURE CUT IN

THE LOW SIDE PRESSURE STAT

THE THERMOSTATIC EXPANSION VALVE

THE THERMOSTAT THAT ACTIVATES THE SOLENOID VALVE

A

The low side pressure stat

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6
Q

WHILE MONITORING THE OPERATION OF A RECIPROCATING REFRIGERATING UNIT YOU OVERSEE THAT THE CYCLING TIMES ARE NORMAL, COMPRESSOR COMPRESSION AND TEMP ARE THE ONLY READING THAT ARE OUTSIDE THE NORMAL RATE. UNDER THESE CONDITIONS SERVICE REQUIREMENTS WOULD INDICATE INSPECTING FOR

FAULTY MACHINE CONTROL

PROPER REFRIGERATION CHARGE

FAULTY COMPRESSOR VALVES

POOR CONDENSER OPERATION / DIRTY TUBES

A

Faulty compressor valves

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7
Q

Which of the following ASHRAE safety groups is the most dangerous

A1

A2

B2

B3

A

B3

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8
Q

You are an RMO assigned to a facility where a refrigerant has been recently changed from a flammable refrigerant to R-22, at the moment you are planning to braze metal. On such making a repair in the machinery room, under these circumstances you ____

MUST ENSURE THE FLAME IS ENCLOSED AND VENTED TO OPEN AIR

MAY MAKE REPAIRS AT LEAST 25 FEET FROM THE REFRIGERANT UNIT

MAY MAKE REPAIRS WITHOUT ANY RESTRICTIONS IF THE REFRIGERATING UNIT IS SHUT DOWN

MAY NOT MAKE REPAIR UNDER ANY CIRCUMSTANCES

A

Must ensure the flame is enclosed and vented to open air

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9
Q

An operator has been assigned to run a centrifugal compressor. Of the following actions a capacity control is most likely to achieve through _____

BYPASS DISCHARGE GAS

ADJUSTMENT OF THE IMPELLER INLET GUIDE PRE-ROTATION VANES

CONDENSER PRESSURE VARIATION

ADDING RE-EXPANSION VOLUME

A

Adjustment of the impeller inlet guide pre-rotation vanes

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10
Q

An RMO needs to vary the flow of refrigerant in the system. A continuous variation in the flow of the system does not include the ____

SOLENOID VALVE

HIGH SIDE FLOAT

THERMAL EXPANSION VALVE

CAPILLARY TUBE

A

Solenoid valve

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11
Q

An operator has been assigned to a large reciprocating machine without unloaders of the following, safety proper procedure for starting the machine is ____

FILTER SUCTION AND DISCHARGE VALVES

SUCTION VALVE AND DISCHARGE BYPASS BOTH OPEN

SUCTION BYPASS AND DISCHARGE VALVE BOTH OPEN

DISCHARGE BYPASS AND SUCTION VALVE BOTH CLOSED

A

Suction valve and discharge bypass both open

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12
Q

An operator has been assigned to run a reciprocating compressor. The following action capacity control would most likely be achieved through ____

OPENING THE SUCTION VALVES WITH SOME FORM OF CONTROL

CONTROLLING THE DISCHARGE PRESSURE

CHANGING THE STROKE AND ADDING RE-EXPANSION VOLUME

RETURNING THE DISCHARGE GAS TO SUCTION

A

Opening the suction valve with some form of control

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13
Q

If a centrifugal compressor is being used in a refrigerations system, and is affected by the condenser, the condenser may be improved by ____

INCREASING THE AMOUNT OF SUPERHEAT

INCREASING THE AMOUNT OF SUB-COOLING

DECREASE THE AMOUNT OF SUPERHEAT

DECREASE THE AMOUNT OF SUB-COOLING

A

Increasing the amount of subcooling

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14
Q

An operator is using a sling psychrometer to measure dry and wet bulb temp on a roof of a building where the cooling tower is located. If during the day the temp remains constant, and wet bulb drops by 5F, and all other conditions remain unchanged, the operator should see ____

HIGH COOLING WATER BEING RETURNED

RISE IN CONDENSER HEAD PRESSURE

LOWER COOLING WATER TEMPERATURE RETURN

NO NOTICEABLE EFFECT OF THE COOLING TOWER TEMP BEING RETURNED

A

Lower cooling water temperature return

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15
Q

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 should be ____

DECREASE IN SUPER HEAT TEMP ENTERING COMPRESSOR

AN INCREASE IN COMPRESSOR HEAD PRESSURE

AN INCREASE IN THE FLOW RATE OF NONCONDENSABLES

CONDENSER TO METERING DEVICE FROZEN

A

An increase in compressor head pressure

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16
Q

What is the purpose of the recovery tank when operating a refrigerant machine?

TO COOL THE REFRIGERANT

TO STORE EXCESS REFRIGERANT

TO FILTER IMPURITIES FROM THE REFRIGERANT

TO INCREASE COMPRESSOR EFFICIENCY

A

To store excess refrigerant

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17
Q

An RMO would expect a relief valve to start functioning (for the section of refrigerant one system being protected) at a pressure most closest to ____

5% OVER DESIGN PRESSURE

THE DESIGN PRESSURE

RECOMMENDED OPERATING PRESSURE FOR NORMAL COOLING CONDITIONS

20% BELOW DESIGN PRESSURE

A

The design pressure

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18
Q

When charging a system with liquid refrigerant with a set of manifold gauges, what position are the valves on the manifold?

HIGH AND LOW VALVES BACKSEATED

HIGH AND LOW VALVES FRONTSEATED

HIGH SIDE BACKSEATED, LOW SIDE FRONTSEATED

HIGH SIDE FRONTSEATED, LOW SIDE BACKSEATED

A

High side backseated, low side front seated

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19
Q

On the liquid line, which is the correct order of placement of the accessories?

SOLENOID VALVE, SIGHT-GLASS, AND DRIER

DRIER, SIGHT-GLASS, AND SOLENOID VALVE

DRIER, SOLENOID VALVE, AND SIGHT-GLASS

NONE OF THE ABOVE

A

Drier, solenoid valve, and sightglass

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20
Q

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 ____

NOT ENOUGH REFRIGERANT IN SYSTEM

EXPANSION VALVE OPEN TOO WIDE

THE COMPRESSOR IS RUNNING CONTINUALLY

COMPRESSOR VALVES ARE LEAKING

A

Expansion valve open too wide

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21
Q

TXV power heads are color coded to match refrigerant charge in the system. What color would the power head have if it was charged with R-22?

ORANGE

GREEN

YELLOW

WHITE

A

Green

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22
Q

When charging an R-12 reciprocating refrigeration system, an operator would want to use warm water to increase the release rate of refrigerant from the drum. To perform this operation the water temp should not exceed the degree of ____ F

80°F

90°F

110°F

130°F

A

90F

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23
Q

According to the safety handbook, how much refrigerant can be recovered into a 60 on container

60 LBS

45 LBS

30 LBS

15 LBS

A

45 lbs

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24
Q

During a walk through the engine room the RMO notices excessive superheat at the evaporator outlet, this would most likely be caused by ____

STARVED EVAPORATOR

LEAK IN SYSTEM

LOW REFRIGERANT CHARGE

ANY OF THE ABOVE

A

Any of the above
(Get the other answers)

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25
Q

In an operating plant using reciprocating compressors, the efficiency of one compressor has decreased. ____ may be the cause of this

LIGHT SUCTION VALVE SPRINGS

HIGH SUCTION PRESSURE

LEAK IN THE SUCTION VALVE

LOW SUCTION PRESSURE

A

Leak in the suction valve

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26
Q

Orifice plates may be used as a metering device component in a centrifugal system. The vessel which they are contained in can also serve as ____

VAPOR RECYCLING UNIT

AN ECONOMIZER

REFRIGERANT CLEANER

EVAPORATOR

A

An economizer

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27
Q

With respect to the fire safety, the ANSI/ASHRAE refrigerant safety classification that is most dangerous is ____

A1

B2

A3

B1

A

A3

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28
Q

At the condenser the refrigerant enters as ____

HIGH PRESSURE GAS AND LEAVES AS LOW PRESSURE LIQUID

HIGH PRESSURE GAS AND LEAVES AS HIGH PRESSURE LIQUID

SUPERHEATED GAS AND LEAVES AS HIGH TEMPERATURE LIQUID

HIGH TEMPERATURE GAS AND LEAVES AS SUPERHEATED GAS

A

High pressure gas and leaves as high pressure liquid

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29
Q

What safety group does ammonia belong?

GROUP 2, B2

GROUP 1, A1

GROUP 3, B1

BOTH A1 AND B1

A

Group 2, B2

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30
Q

According to nyc fire code classification of refrigerant, ammonia would fall under which group?

GROUP 1

GROUP 2

GROUP 3

GROUP 4

A

Group 2

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31
Q

Which type of pump is considered non-positive displacement pump?

RECIPROCATING

ROTORY, SCREW

SCROLL

CENTRIFUGAL

A

Centrifugal

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32
Q

If the eliminator plates located below the fan in an induced draft-cooling tower have become clogged, of the following this would most likely result in ____

DAMAGE TO FAN BLADES

INCREASE IN COOLING TOWER WATER TEMP BEING RETURNED

DECREASE IN MAKEUP WATER REQUIREMENTS

A DROP IN WET BULB TEMP

A

Increase in cooling tower water temp being returned

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33
Q

Convert 18” vacuum to psia

7.7

0.6

5.9

23.5

A

5.9
(Look up formula for conversion)

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34
Q

Superheated vapor protects the compressor against liquid intake. What would the RMO notice if compressor was receiving liquid?

HEAD PSI DROPPING TO LOW

DECREASE THE CAPACITY OF THE COMPRESSOR AND REFRIGERATION SYSTEM

NON-CONDENSABLES ARE MORE PRONE TO COLLECT IN THE SYSTEM

FROST MAY DEVELOP IN THE SUCTION LINE

A

Frost may develop in the suction line

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35
Q

If an electric motor is rewound to cut resistance by 1/2, all other factors being equal, the motor power would ____

REDUCE BY 1/2

INCREASE BY A FACTOR OF 2

STAY THE SAME

INCREASE BY A FACTOR OF 4

A

Increase by a factor of 2

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36
Q

AT THE PLANT WHERE YOU ARE EMPLOYED A REFRIGERATING UNIT IS BEING TAKEN OUT OF SERVICE FOR MAJOR REPAIRS AND THAT YOU HAVE BEEN ASSIGNED TO WITHDRAW REFRIGERANT FOR STORAGE IN A 40 GALLON CONTAINER. ACCORDING TO THE NYC FIRE HANDBOOK, THE MAXIMUM QUANTITY OF REFRIGERANT IN GALLONS THAT YOU MAY LEGALLY FILL EACH CONTAINER WITH UNDER ANY CIRCUMSTANCES IS ____

36

30

24

32

A

30 (that’s 75% max capacity)

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37
Q

An RMO was instructed to charge a 60 ton plant with R-134A refrigerant. The operator would most likely find the charging valve on the ____

HIGH PRESSURE SIDE OF THE EQUIPMENT

LOW PRESSURE SIDE OF THE EQUIPMENT

DISCHARGE SIDE OF THE EQUIPMENT

RECIEVER

A

Low pressure side of the equipment

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38
Q

When changing water to ice, what must be removed?

SPECIFIC HEAT

SUPER HEAT

LATENT HEAT

SENSIBLE HEAT

A

Latent heat

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39
Q

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 ____

113

313

213

13

A

213
(Look up reasoning)

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40
Q

When properly purging you should ____

PURGE AT RAPID RATE

PURGE WITH COMPRESSOR ON

STOP WHEN PRESSURE CEASES TO DROP

RUN THE CONDENSER AS MUCH AS POSSIBLE

A

Stop when pressure ceases to drop

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41
Q

A reciprocating refrigeration compressor cylinder HAS A 12” BORE AND 16” STROKE. THE VOLUME OF REFRIGERANT IN CUBIC INCHES WOULD BE CLOSER TO ____

1204

1002

1808

1406

A

1808
(Look up)

42
Q

A rupture disc in a centrifugal refrigerating machine is normally located on the ____

CONDENSER

ECONOMIZER

COMPRESSOR DISCHARGE

EVAPORATOR

A

Evaporator

43
Q

Initial OAT is 50F. You have been informed the OAT has dropped to 10C. The temperature in F is ____

32

28

40

18

A

32
(Look up formuler)

44
Q

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 HEAT OF EVAPORATION OF THE COOLING TOWER

IN THE ECONOMIZER

IN THE EVAPORATOR

CONDENSER WATER OUTLET

A

As heat of evaporation of the cooling tower

45
Q

Frost appearing on the suction line an part of the compressor is caused by ____

SLUGGING COMPRESSOR

FLOODED EVAPORATOR

STARVED EVAPORATOR

UNINSULATED SUCTION LINE

A

Flooded evaporator

46
Q

A pump affects the pressure of a fluid or gas by ____

REDUCING PRESSURE

RAISING PRESSURE

REGULATING PRESSURE

STABILIZING PRESSURE

A

Raising pressure

47
Q

The bulb to a TXV has fallen off and the room is at 85F. The evaporation would ____

STARVE

FLOOD

INCREASE SUPERHEAT

RESPOND NORMALLY

A

Flood

48
Q

A vertical 12” water pipe from the roof has a pressure gauge reading of 120 psi. How tall is the pipe?

277 FEET

1,440 INCHES

1,440 FEET

277 INCHES

A

277 feet
(Look up)

49
Q

What is the disadvantage of having a low head pressure?

EVAPORATOR WOULD FLOOD

COMPRESSOR WOULD HUNT

EXPANSION VALVE WOULD NOT FEED PROPERLY

CONDENSER COULD NOT SUB-COOL

A

Expansion valve would not feed properly

50
Q

If the suction pressure is 60 psig and the discharge is 180 psig, what would the compression ratio be?

5:1

3:1

2:6

4:1

A

3:1

51
Q

A constant pressure expansion valve is being used instead of a thermostatic expansion valve under various loads will ____

STARVE THE EVAPORATOR

FLOOD THE EVAPORATOR

OPERATE BETTER THAN TEV

BOTH A AND B ARE CORRECT

A

Both A and B
(Fucker)

52
Q

Which is not used as a cooling medium in a indirect system?

R-22

CALCIUM CHLORIDE

GLOCOL

SODIUM CHLORIDE

A

R-22

53
Q

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 MEANT, OF THE FOLLOWING THE POWER CONSUMPTION IS DETERMINED BY THE APPLICATION OF THE FORMULA:

WATTS = VOLTS X AMPS X OHMS

WATTS = VOLTS X AMPS X HERTZ

WATTS = VOLTS X AMPS

WATTS = VOLTS X AMPS X POWER FACTOR

A

Watts = Volts * Amps * power factor

54
Q

An operator is running to centrifugal condenser 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 REDUCTION ON BOTH THE WATER FLOW RATE AND PRESSURE INTO THE CONDENSER

A REDUCTION IN TOTAL FLOW RATE TO CONDENSER

A REDUCTION IN WATER PRESSURE AT THE CONDENSER INLET

FOR THE PUMPS TO COMPENSATE TO MAINTAIN BOTH THE FLOW RATE AND DISCHARGE PRESSURE

A

A reduction to total flow rate to the condenser

55
Q

A pressure relief valve that is installed on a reciprocating compressor that is using R-12 is normally set ____

ACCORDING TO DESIGN PRESSURE

ACCORDING TO OPERATING PRESSURE

LOWER THAN THE HIGH PRESSURE CUT OUT

AT LOW PRESSURE CUT OUT PLUS 50%

A

According to design pressure

56
Q

Which refrigerant requires approval for use by the NUC fire department?

R-22

R-12

CARBON DIOXIDE

BUTANE

A

Butane

57
Q

When installing a service valve to isolate a dual pressure device while keeping system in service, you would use a ____

TWO WAY VALVE

THREE WAY VALVE

PLUG VALVE

STOP VALVE

A

Three way valve

58
Q

The solenoid unloaders on reciprocating compressors are designed to unload ____

ALL THE CYLINDERS

THE CLEARANCE SPACES IN THE CYLINDERS

CONTROL CAPACITY BY SHUTTING DOWN THE COMPRESSOR

CYLINDERS THAT CAN BE UNLOADED

A

The clearance spaces in the cylinders

59
Q

The most common metering device used today in a reciprocating commercial refrigeration system over 3 tons is ____

AUTOMATIC EXPANSION VALVE

THERMOSTATIC EXPANSION VALVE

LOW SIDE FLOAT

HIGH SIDE FLOAT

A

Thermostatic expansion valve

60
Q

Efficiency of the refrigeration cycle is affected by the operation of the condenser. Of the following a more efficient operation of a centrifugal compressor results from ____

RAISE THE CONDENSER LIQUID LEVEL TO THE MAXIMUM

PRODUCE A LARGE AMOUNT OF LIQUID SUB-COOLING

RAISE THE CONDENSER HEAD PRESSURE

LOWER THE CONDENSER PRESSURE

A

Lower the condenser pressure

61
Q

An RMO observes a gauge that reads the saturation pressure of a refrigerant. If chilled water is being circulated as the cooling medium, this reading can best be used to estimate the ____

CHILLED WATER TEMPERATURE RETURNING FROM THE BUILDING SPACES BEING COOLED

TEMPERATURE OF THE CHILLED WATER BEING PUMPED TO THE BUILDING SPACES THAT ARE BEING COOLED

PRESSURE OF CHILLED WATER BEING PUMPED TO THE BUILDING SPACES THAT ARE BEING COOLED

COOLING TOWER EFFICIENCY

A

Temperature of the chilled water being pumped to the building spaces that are being cooled

62
Q

Why is a spring loaded PRV better to use than a fusible plug?

LESS EXPENSIVE

EASY AVAILABILITY

FUSIBLE PLUG CANNOT RESET

LARGER

A

Fusible plug cannot reset

63
Q

Of the following, under what conditions of the heat in BTU/per min absorbed by the condenser water in a refrigerating plant is greater?

AT HIGHER EVAPORATIVE TEMPERATURE AND LOW CONDENSER TEMPERATURE

LOW EVAPORATIVE TEMPERATURE AND HIGH CONDENSER TEMPERATURE

HIGHER EVAPORATIVE TEMPERATURE AND HIGH CONDENSER TEMPERATURE

LOW EVAPORATIVE TEMPERATURE AND LOW CONDENSER TEMPERATURE

A

Low evaporative temperature and low condenser temperature

64
Q

What would happen if the spring in the TEV broke?

FLOOD THE EVAPORATOR

STARVE THE EVAPORATOR

NO CHANGE

DAMAGE FEELER BULB

A

Flood the evaporator

65
Q

What refrigeration systems are most likely to leak refrigerant in building spaces that are being cooled?

INDIRECT SYSTEMS

DIRECT SYSTEMS

INDIRECT CLOSED SYSTEMS

INDRIECT OPEN SYSTEMS

A

Direct systems

66
Q

If you were running three compressors, which best describes the state of refrigerant leaving the third compressor?

MOSTLY LIQUID, SOME VAPOR

MOSTLY VAPOR, SOME LIQUID

SLIGHTLY SUPERHEATED VAPOR

HIGHLY SUPERHEATED VAPOR

A

Highly superheated vapor

67
Q

Machine room safety standards have been established by ____

ARI-700

ARI-740

ASHRAE 34

ASHRAE 15

A

ASHRAE 15

68
Q

Assume that the operator has a choice of 4 valves to select from and wants to minimize pressure drop. Of the following the operator should avoid the use of ____

BALL

PLUG

GLOBE

GATE

A

Globe

69
Q

What is the purpose of the equalizer line?

TO EQUALIZE PRESSURE IN THE TEV ALONG THE DIAPHRAM AND BELLOWS

TO MAKE UP FOR THE PRESSURE DROP IN EVAPORATOR

TO METER REFRIGERANT

TO REMOVE PRESSURE DROP

A

To make up for the pressure drop in the evaporator

70
Q

IN a compressor’s electrical box one of the hot wires is touching the metal box, what would most likely happen?

COMPRESSOR WOULD OVERHEAT

COMPRESSOR WOULD OVERLOAD AND SHUT OFF

RMO WORKERS CAN RECEIVE ELECTRIC SHOCK IF THEY TOUCH IT

NOTHING

A

RMO workers can receive electrical shock if they touch it

71
Q

R-11 and R-123 refrigerants are ____

OXYGEN DEPLETING

HEAVIER THAN AIR

ARE CLASS-1 AND CLASS-2 SUBSTANCES DEFINED BY EPA

ALL OF THE ABOVE

A

All of the above
(Dammit)

72
Q

What is the TEV diaphragm made of

RUBBER

METAL

PLASTIC

GRAPHITE

A

Metal

73
Q

In an emergency if you must dump refrigerant into the sewer, you will dump only when ____

SEWER IS NOT CONNECTED TO A STORM DRAIN

FIRST CONFIRM THAT REFRIGERANT IS NOT FLAMMABLE

FACILITY MANAGER APPROVES IT

YOU DISCHARGE UNDER THE SUPERVISION OF THE FIRE DEPT.

A

You discharge under the supervision of the fire department

74
Q

An RMO notices a knocking reciprocating compressor. The RMO is assured the compressor has no worn parts. The most probable cause of the knocking is ____

INADEQUATE LUBRICATION

LIQUID SLUGGING

CRANKCASE PRESSURE TO LOW

SUCTION AND DISCHARGE NOT OPENING AND CLOSING

A

Liquid slugging

75
Q

When installing a pipeline and you need to make a 90 degree elbow, which is the best way?

BEND PIPE

USE FACTORY MADE 90° ELBOW AND BRAZE

USE FLEXIBLE TUBING

USE TWO 45° ELBOWS

A

Use factory made 90 degree elbow and braze

76
Q

1000 BTU’s are removed from 100 lbs of water at a temperature of 55F. What is the final water temperature?

55°F

50°F

45°F

40°F

A

45 F
(Yeah you know what to do)

77
Q

An operator is using a portable recovery vessel and compressor to recover vapor refrigerant from a machine. The recovery process will slow down because ____

COMPRESSOR CAPACITY WILL DECREASE

VAPOR DENSITY WILL INCREASE

THE REFRIGERANT TEMPERATURE WILL INCREASE

THE REFRIGERANT PRESSURE WILL DECREASE

A

The refrigerant pressure will decrease

78
Q

Due to a cold front there was a harsh drip in OAT, the most likely effect of this condition on the operation of the reciprocating machine would be that the thermostat causes the solenoid valve to ____

CLOSE, THE COMPRESSOR PUMPS DOWN AND SHUTS DOWN ON LOW PRESSURE

CLOSE AND THE COMPRESSOR WILL START ON HIGH PRESSURE

OPEN AND COMPRESSOR WILL PUMP DOWN AND GO OFF ON HIGH PRESSURE

OPEN AND COMPRESSOR WILL CONTINUE TO RUN AT REDUCED SPEED

A

Close, the compressor pumps down and shuts down on low pressure

79
Q

As an RMO in charge you are requested to replace the gauge on the high side of the refrigeration system. The pressure graduation rate should be ____

1.2 OF DESIGN PRESSURE (AT LEAST)

THE RUPTURE GUARD HAS TO BE REPLACED ALSO

THE GAUGE HAS TO BE A COMPOUND GAUGE

THE GAUGE SHOULD BE GRADUATED TO PRESSURE

A

1.2 of design pressure (at least)

80
Q

A jet ejector is used to raise oil mixed with the refrigerant which has collected at the bottom of the evaporator. If restricted ____

THE FLOW OF OIL WILL NOT BE EFFECTED

YOU WILL HAVE INSUFFICIENT HEAD TO LIFT THE OIL

THE TEMPERATURE OF THE REFRIGERANT EXITING THE JETS WILL DECREASE

THE OIL IN THE BOTTOM OF THE CHILLER WILL NOT LIFT IF IT BECOMES MIXED WITH LESS REFRIGERANT

A

You will have insufficient head to lift the oil

81
Q

Assuming all conditions remain constant, the HP per ton of refrigerating effect would most likely ____

DECREASE AS THE SUCTION PRESSURE INCREASES

INCREASE AS AS THE SUCTION PRESSURE INCREASES

DECREASE AS THE DISCHARGE PRESSURE DECREASES

INCREASE AS THE DISCHARGE PRESSURE INCREASES

A

Decrease as the suction pressure increases

82
Q

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 ____

R-12

CARBON DIOXIDE

AMMONIA

R-22

A

Ammonia

83
Q

Low condensing pressure is not good because ____

LIQUID LEVEL IN CONDENSER WILL FALL TOO LOW

COMPRESSOR WILL WORK HARDER

EXPANSION VALVES WILL NOT FEED PROPERLY

HEAD PRESSURE WILL INCREASE

A

Expansion valves will not feed properly

84
Q

Multistage centrifugal compressors each stage ____

TIP SPEED IS MORE WITH EACH STAGE

EVERY STAGE IS IDENTICAL

HANDLES MORE REFRIGERANT

HAS SMALLER VOLUME

A

Tip speed is more with each stage

85
Q

Heat transfer rate in the condenser will ____

INCREASE WITH THE VELOCITY OF THE WATER IN THE TUBES

SHOW ONLY A SMALL INCREASE IF TUBES ARE DESCALED

INCREASE WITH A LOWER LEAVING WATER TEMPERATURE DIFFERENCE

SHOW THE LEAST BENEFIT FOR DESCALING THE TUBES AT HIGH WATER VELOCITIES

A

Increase with the velocity of the water in the tubes

86
Q

A motor has 4 belts, the center belt is worn you would ____

CHANGE THE CENTER BELT

CHANGE CENTER BELT AND ALL OTHER BELTS

CHANGE THE OTHER BELTS

CHANGE TO DIRECT DRIVE SYSTEM

A

Change center and all other belts

87
Q

Why should you charge with vapor?

YOU COULD BREAK THE RUPTURE GUARD WITH LIQUID

YOU CAN ENTRAIN THE OIL IN THE REFRIGERANT WITH LIQUID

YOU CAN FREEZE WATER IN THE TUBES WITH LIQUID

YOU CAN OVER CHARGE THE SYSTEM WITH LIQUID

A

You can freeze water in the tubes with liquid

88
Q

An in-line refrigerant cleaning system is advisable because ____

NON-CONDENSEABLES CANNOT BE PROPERLY PURGED

REFRIGERANT REACTS WITH THE LUBRICATION OIL

REFRIGERANT SYSTEM IS HIGH PRESSURE

REFRIGERANT IS A TOXIC CLASS

A

Refrigerant reacts with the lubrication oil

89
Q

WHEN OPERATING A REFRIGERATION UNIT, THE OPERATOR NOTICES THAT THE MOTOR COMPRESSOR IS SHORT CYCLING, THE UNIT IS USING A LOW SIDE FLOAT VALVE. THE FOLLOWING SERVICE REQUIREMENTS WOULD INDICATE

INSPECTION SHOULD BE MADE FOR DIRTY TEV STRAINER

PARTIALLY CLOGGED DISCHARGE LINE

CHECK COMPRESSOR WIRING, FOR OVERLOADED EQUIPMENT

ADDITIONAL REFRIGERANT BE CHARGED

A

Additional refrigerant be charged

90
Q

R-22 is ____

ODORLESS

ETHER LIKE ODER WHEN MIXED WITH AIR

EXPLOSIVE

BOILS AT A HIGHER TEMPERATURE THAN R-12

A

Odorless

91
Q

An automatic purge unit is required for those refrigerating systems that have ____

DOUBLE INDIRECT OPEN SPACE SYSTEMS

SYSTEMS OPERATING BELOW ATMOSPHERIC PRESSURE

ABSORPTION COMPRESSORS

OUTSIDE AIR DAMPERS

A

Systems operating below atmospheric pressure

92
Q

The most correct way to describe a braised joint is ____

PRESSURE FITTING

GAS TIGHT FITTING

START TO MELT AT 400°F

START TO MELT AT 500°F

A

Gas tight fitting

93
Q

YOU ARE AN MO ASSIGNED TO THE 3RD FLOOR IN AN ASSEMBLY ROOM. ATTENDANCE AND TEMP HAVE INCREASED DURING THE AFTERNOON, THEREFORE A COLDER WATER SUPPLY IS TO BE PRODUCED. IN ORDER TO ACCOMPLISH THIS YOU SHOULD ____

RE-ADJUST THE TEV SUPERHEAT SETTING

DEACTIVATE THE FREEZE STAT

RAISE THE COMPRESSOR DISCHARGE OPERATING PRESSURE

LOWER THE COMPRESSOR SUCTION OPERATING PRESSURE

A

Lower the compressor suction operating pressure

94
Q

What is the purpose of having a service valve stem cap?

TO PROTECT FROM BEING INADVERTENTLY TURNED FROM ITS POSITION AND FROM BEING DAMAGED

TO LET YOU KNOW THE POSITION OF THE VALVE

TO LET YOU NOTICE VALVE FROM A DISTANCE

TO CAP OFF VALVE SO THAT UT CAN NEVER BE USED

A

To protect from being inadvertently turned from its position and being damaged

95
Q

One disadvantage of using bribes as a cooling medium is corrosion.in commercial practice, corrosion and rust is reduced by the addition of ____ to the brine solution

WEAK ACID SOLUTION

ZINC COMPOUNDS

GLYCOLS

DI-CHROMATES

A

Di-chromates

96
Q

If you just purchased a thermometer and need to check if it’s working properly, how would you do it?

TOUCH IT IN A POT OF BOILING WATER

TOUCH IT TO BUCKET OF ICE / ICE WATER

COMPARE TO 2 OTHER THERMOMETERS

COMPARE TO ANOTHER RMO THERMOMETER

A

Touch it to a bucket of ice/ice water

97
Q

A bimetal disk or klixon is used to ____

STOP THE REFRIGERATION EQUIPMENT BEFORE EXCESSIVE PRESSURE OCCUR

STOP THE REFRIGERATION EQUIPMENT AT A PREDETERMINED MINIMUM OPERATING PRESSURE

PROTECT THE WIRING AND COMPONENTS AGAINST EXCESSIVE CURRENT DRAW

PROTECT THE COMPRESSOR AGAINST THE LOSS OF OIL PRESSURE

A

Protect the wiring and components against excessive current draw

98
Q

Of the following the most undesirable property in refrigerant is ____

LOW CORRESPONDING COMPRESSOR DISCHARGE TEMP

LOW VISCOSITY

LOW LATENT HEAT

LOW CORRESPONDING OPERATING PRESSURE

A

Low latent heat

99
Q

If you are using a portable compressor unit to remove vapor. What would happen when you are recovering?

COMPRESSOR SPEED IS DECREASED

VAPOR DENSITY IS DECREASED

REFRIGERANT TEMPERATURE WILL DROP

COMPRESSOR EFFICIENCY WILL DECREASE

A

Vapor density is decreased

100
Q

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?

WATER, OIL, REFRIGERANT

OIL, REFRIGERANT, WATER

REFRIGERANT, OIL, WATER

OIL, WATER, REFRIGERANT

A

REFRIGERANT, OIL, WATER

Refrigerant Machine Operator Practical (5 decks)

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