Refrigerant Machine Operator Practice Test #4

Question 1

Ejector pumps are employed on oil tanks of a centrifugal system to

Vent air from the oil tank

Vent refrigerant from the oil tank

Return oil from the condenser

Return oil from the chiller

Answer 1

Return oil from the chiller

Question 2

As an RMO, you are responsible for two air cooled split systems handling computer rooms and are required to run all year round. These units are most likely equipped with:

Crankcase heaters and condenser damper

Crankcase heater and hot gas by-pass

Condenser damper and VFD

Condenser damper and hot gas by-pass

Answer 2

Condenser damper and hot gas by-pass

Question 3

In commercial refrigeration, the room thermostat controls the liquid line solenoid valve but the control that starts and stops the compressor is the :

Low temperature stat

Low pressure cut-out

Low pressure control

Low oil safety

Answer 3

Low pressure control

Question 4

All of the following can cause you to lose your vacuum on the surface condenser except:

Open atmospheric vent valve

Ruptured cooling water tube

No priming water in the hot well

A sudden drop in load

Answer 4

A sudden drop in load

Question 5

As an RMO you encounter a large steam turbine. The type of device you would most likely find controlling the speed of the turbine is:

A hydraulic governor assembly

A mechanical governor assembly

An automatic over speed trip

An automatic gimple valve

Answer 5

A hydraulic governor assembly

Question 6

Of the following, the action that controls the capacity of the centrifugal compressor provided with variable vane control:

Altering the size of the passage wheel

Controlling the cylinder unloaders as capacity changes

Changing the compressor clearance spac

Changing the tip speed of the compressor wheel

Answer 6

Altering the size of the passage wheel

Question 7

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

Raising the condenser liquid level to maximum

Produce large amounts of subcooling

Raising the condenser head pressure

Lowering the condenser pressure

Answer 7

Produce large amounts of subcooling

Question 8

A truck with 5 tons of ice stuck on the side of the road with no refrigeration. How many BTUs is required to melt 5 tons of ice at 32 deg F to 5 tons of water at 32 deg F in 1

60,000 BTUs

1,400,000 BTUs

288,000 BTUs

Cannot be done in 1 hr.

Answer 8

60,000 BTUs

The correct answer is 60,000 BTUs because it takes 1 BTU to raise the temperature of 1 pound of water by 1 degree Fahrenheit. Since there are 2000 pounds in a ton, and the temperature change is 32 degrees, the total BTUs required to melt 5 tons of ice at 32 degrees Fahrenheit to 5 tons of water at 32 degrees Fahrenheit is 5 tons * 2000 pounds/ton * 32 degrees = 320,000 BTUs. However, since the question specifies that this needs to be done in 1 hour, the total BTUs required per hour is 320,000 BTUs/hour. Therefore, the correct answer is 60,000 BTUs.

Question 9

The design and sequence of operations of an automatic expansion valve causes it to:

Decrease superheat on an increase in load

Increase superheat on a decrease of load

Close on decrease in pressure

Close on an increase in pressure

Answer 9

Close on an increase in pressure

Question 10

What position is the gauge manifold in before you attach to system?

Both cracked

Front seated

Low side back seated, high side front seated

Back seated

Answer 10

Front seated

Question 11

As the load on a reciprocating chiller decreases, the most correct sequence of operation is as follows

Compressor goes into hot gas by-pass, unloads and shuts off

Compressor shuts off, unloads and then goes into hot gas by-pass

Compressor unloads, then hot gas by-passes and shuts down

None of the above

Answer 11

Compressor unloads, then hot gas by-passes and shuts down

Question 12

Which of the following conditions will cause a system’s compressor to pump down?

A rise in space temperature

A rise in head pressure

A decrease in space temperature

A high differential setting on the low pressure controller

Answer 12

A decrease in space temperature

Question 13

The job of the kingsbury bearing on a steam turbine is to:

To maintain axial clearance

To keep vertical clearance

To compensate for axial thrust

To not allow and shaft movement

Answer 13

To compensate for axial thrust

Question 14

As an RMO inspecting the discharge line of a reciprocating compressor you notice a device at the furthest point away from the compressor. This device is most likely there to:

Clean the refrigerant

Separate the moisture from the refrigerant

Return oil to the compressor

Muffle the noise from the compressor

Answer 14

Return oil to the compressor

Question 15

An operator reads the valve tag on a pressure relief valve and notices that the valve is set to unload at 20 PSIG, the corresponding set pressure in inches of mercury would be nearing:

90

64.4

70.4

30.3

Answer 15

70.4

1 psi = 2.036 inches of mercury

Question 16

The pressure in a pipe is 55 psi, there are 15 ft per floor. How many floors are

5

6

7

8

Answer 16

8

The pressure in a pipe is 55 psi and there are 15 ft per floor. To determine the number of floors, we need to divide the pressure by the height per floor. So, 55 psi divided by 15 ft gives us approximately 3.67. Since we cannot have a fraction of a floor, we round up to the nearest whole number, which is 4. Therefore, the correct answer is 8 floors.

Question 17

If the thermal bulb is clamped to the pipe right after expansion valve, what would take place?

The expansion valve would continually flood the coil

The expansion valve would freeze in the wide open position

This is incorrect and would starve the cooling coil

Oil and moisture would likely accumulate

Answer 17

This is incorrect and would starve the cooling coil

Question 18

Radial clearance in reference to a steam turbine is defined as

Distance from end to end of shaft

Distance between radial bearings

Distance between the top of the rotating blades and the casing

Distance between the packing and the shaft

Answer 18

Distance between the top of the rotating blades and the casing

Question 19

What is the cooling medium of the cooling towers?

Air

Water

Air and water

Fan

Answer 19

Air

Question 20

Types of steam turbines include all of the following except:

Impulse steam turbines

Reaction steam turbines

Impulse reaction steam turbine

None of the above

Answer 20

None of the above

Question 21

Mechanical seals are typically made of:

Carbon and stainless steel

Ceramic and carbon

Ceramic and graphite

Graphite impregnated rope or string

Answer 21

Carbon and stainless steel

Question 22

When looking at a wiring diagram for a 20 ton split system, you would expect to find the following information.

The path that current takes through the system

A point to point detail of how the wires are run

A pictorial of component position

Amp ratings for all loads

Answer 22

A point to point detail of how the wires are run

Question 23

Packing glands on centrifugal pumps are typically made out of what types of materials?

Graphite impregnated rope or string

Ceramic and carbon with rubber retainers

Centrifugal pumps do not need packing glands

Stuffing box filled with grease

Answer 23

Graphite impregnated rope or string

Question 24

The primary function of the steam eductors on the surface condenser is to:

Condense the steam

Create a vacuum

Separate the steam and air

Safety device only

Answer 24

Create a vacuum

Question 25

As an RMO running a reciprocating chiller, you notice oil foaming the sight glass. The cause for this condition could be:

A sudden drop in crankcase pressure

A faulty crankcase heater

Liquid refrigerant mixing with the oil in the off cycle

All of the above

Answer 25

All of the above

Question 26

An automatic purge unit is required on units:

With centrifugal compressors

Containing low pressure refrigerants

Absorption systems

Double indirect open spray systems

Answer 26

Containing low pressure refrigerants

Question 27

An RMO notices that the diameter of the suction line is 36” and the diameter of the discharge line is 18”. What can we determine from this statement?

The unit is piped wrong because the diameters should be opposite

The cold refrigerant vapor needs less space than a hot vapor

The high pressure line needs more diameter to handle the pressure

The higher the vapor pressure is, the less volume is needed

Answer 27

The higher the vapor pressure is, the less volume is needed

Question 28

Shaft glands on a steam turbine are located:

Front and rear of turbine

Wherever the shaft emerges from the casing or steam could leak

Wherever air could leak out of the turbine

Wherever oil can leak from the lubrication system

Answer 28

Wherever the shaft emerges from the casing or steam could leak

Question 29

While inspecting the machine room, the compressor is cycling on and off, what is causing the compressor to cycle on and off?

Refrigerant overcharge

Refrigerant undercharge

Compressor valves problems

Non condensables in the system

Answer 29

Refrigerant undercharge

Question 30

When looking at a large semi-hermetic reciprocating compressor, you would expect to find:

Suction and discharge lines parallel to each other

Suction and discharge lines perpendicular to each other

Depends on the amount of cylinders

Suction on top and discharge off the bottom

Answer 30

Suction and discharge lines perpendicular to each other

Question 31

If the temperature outside drops b 8 deg.C, what is the equivalent drop in def.F?

4 deg.F

40 deg.F

14 deg.F

8 deg.F

Answer 31

14 deg.F

If the temperature outside drops by 8 deg.C, the equivalent drop in def.F can be calculated using the formula: def.F = (9/5 * deg.C) + 32. Plugging in the value of -8 deg.C, we get def.F = (9/5 * -8) + 32 = 14 deg.F. Therefore, the correct answer is 14 deg.F

Question 32

The medium/mediums for cooling in an evaporative condenser is/are:

Air only

Refrigerant and water

Water and air

Glycol and air

Answer 32

Water and air

Question 33

What is the most used regulation book in the U.S. used by the RMO?

NFPA

USEPA

Federal Regulation book

NYC building code

Answer 33

USEPA

Question 34

You are the RMO of a facility which contains a 750 ton centrifugal Trane chiller. The chief ask you to order extra refrigerant for the upcoming season. If the machine charge is determined to be 1500lbs, how much refrigerant can you store without being in violation of the code?

Whatever the chief engineer deems safe

Whatever can be tied down and stored safely

200lbs of refrigerant

330 lbs of refrigerant

Answer 34

330 lbs of refrigerant

Question 35

There are two refrigerating systems. System “A” operates with a suction pressure of 18 PSIG and a speed of 230 RPM. It is absorbing 800 BTUs per minute in its evaporator. The second system “B” is operating with a suction pressure of 22 PSIG and a speed of 300 RPM. It is absorbing 600 BTUs per minute from a brine tank. From the data given it can be said that:

“A” is producing three tons and “B” is producing for tons

“A” is producing four tons and “B” is producing four tons

“A” is producing four tons and “B” is producing three tons

“A” is producing three tons and “B” is producing three tons

Answer 35

“A” is producing four tons and “B” is producing three tons

1 ton of refrigerant is = 12000 BTU’s per hour

Question 36

What is the diaphragm of the power assembly of a TEV made of?

Copper

Flexible rubber

Flexible steel

N/A

Answer 36

Flexible steel

Question 37

You notice that the second stage compressor on your reciprocating chiller has foaming in the oil sight glass. As an operator you should check for:

Excessive charge

Burnt out crankcase heater

Moisture in the system

Too much oil

Answer 37

Burnt out crankcase heater

Question 38

An automatic oil trap is installed in the high side of a refrigeration system. When the float of the traps lifts it allows:

Hot oil to defrost the coils

Hot oil to go through the stuffing box

Oil to drain off into the receiver reservoir

Oil to leave the trap and return to the compressor

Answer 38

Oil to leave the trap and return to the compressor

Question 39

A valve that will not provide continuos flow of refrigerant through the circuit is the:

Globe valve

Service valve

Solenoid valve

TXV

Answer 39

Solenoid valve

Question 40

The recirculation valve on a surface condenser is controlled by the:

Hot well level control

The condensate pumps

pneumatic controller

Oil pump pressure

Answer 40

Hot well level control

Question 41

Why is it important to minimize moisture in the inlet steam to a turbine?

Prevent damage to turbine blades

It takes longer to warm up with moisture

Acids can form in the surface condenser

Moisture has no effect, steam is heated moisture

Answer 41

Prevent damage to turbine blades

Question 42

What is the state of the refrigerant as it enters and exits the compressor?

Low temperature liquid in and high temperature liquid out

Low temperature vapor in and high temperature vapor out

Low temperature in and high temperature out

Low pressure in and high pressure out

Answer 42

Low temperature vapor in and high temperature vapor out

Question 43

After condensate water leaves the recirculation valve, where does it go?

Back to the boiler

Down the drain back

Back to the hot well for priming

Back to turbine

Answer 43

Back to the hot well for priming

Question 44

Which one of the following will connect to the middle port on a gauge manifold?

Solenoid valve

King valve

Vacuum pump

Suction or discharge service valves

Answer 44

Vacuum pump

Question 45

When considering the rate of BTUs rejected by the condenser, an important point for the operator to remember is:

Will increase if you oversize the tower

Will decrease as the water temperature goes down

Will increase as the velocity goes up

Will show no difference as long as the water temperature is the same

Answer 45

Will increase as the velocity goes up

Question 46

On a water cooled chiller, the heat that is absorbed by the chilled water is:

Rejected to the ambient air as sensible heat

Rejected as latent and sensible heat heat to the ambient air

Minimal in comparison to the volume of water

Rejected by the compressor

Answer 46

Rejected as latent and sensible heat heat to the ambient air

Question 47

It has been determined that the oil level in a particular refrigeration system is low, additional oil should be charged into the system by

Pumping it through the suction service valve

Pumping it into the compressor crankcase

Pumping it into the king valve

Using the gauge manifold to draw through both service valves simultaneously

Answer 47

Pumping it into the compressor crankcase

Question 48

Solenoid valves are characterized by an electromagnet. Which of the following will take place when a normally close solenoid is energized?

Valve disc will rotate 180 degrees

Valve will meter flow of refrigerant to evaporator

Valve plunger will lift off the seat

Magnetic force will close contact

Answer 48

Valve plunger will lift off the seat

Question 49

What is the minimum required times that the RMO needs to perform rounds on equipment and fill out the log book, per NYC Fire Dept.

Once per shift

Once a day

Every two hours

Every hour

Answer 49

Once per shift

Question 50

A systems condenser water pump has been shut down for service. When it is turned back on, it is discovered that it is not moving water. What should the RMO do?

Check the shaft bearings for grease

Check the contacts with the voltmeter for correct voltage

Open the petcock and bleed air from volute

Bleed excess water pressure from the bottom plug

Answer 50

Open the petcock and bleed air from volute

Question 51

As and RMO in charge of a refrigeration machine in your building controlling the capacity of the machine, how does the solenoid valve unloader get activated?

With spring pressure

With pneumatic pressure

With electric current in a coil causing the plunger to lift

None of the above

Answer 51

With electric current in a coil causing the plunger to lift

Question 52

An RMO is inspecting a centrifugal pump and he notices excessive water leaking from the mechanical seal. The RMO should:

Tighten evenly to get a steady drip

This is normal for a mechanical seal

Shut down the pump, turn on the standby and call for pump service

Order a new pump because mechanical seals cannot be replaced

Answer 52

Shut down the pump, turn on the standby and call for pump service

Question 53

Oil that has been separated from the refrigerant is returned to the compressor and tied into the

Oil charging valve

Discharge service valve

Oil pump suction

Compressor crankcase

Answer 53

Compressor crankcase

Question 54

When conducting a routine tour of the plant, an RMO notices a significant increase in superheat for a reciprocating compressor. Of the following, the most likely cause of this would be?

Scale particles lodged in the TEV

Unraveling of the insulation covering the thermal bulb of the TEV

Overcharge of refrigerant

Noncondensables in the system

Answer 54

Scale particles lodged in the TEV

Question 55

After completing repair to a refrigeration system, you leak check the system with your electronic leak detector. After no leaks are found, proper disposal of the R-22 and nitrogen mix to :

Separate refrigerant from nitrogen and vent

Recover the mixture and mark to be destroyed

Vent the mixture to the outside air

You cannot use R-22 for this purpose

Answer 55

Vent the mixture to the outside air

Question 56

The use of oil in the refrigeration machine is to

Mix the oil with liquid refrigerant

Add non condensables to refrigerant

Reduce friction in the compressor parts

None of the above

Answer 56

Reduce friction in the compressor parts

Question 57

Which of the following statements should be imprinted on the body of a fusible plug?

Temperature at which the fusible member melts

Date manufactured

Busting pressure

Maximum operating pressure

Answer 57

Temperature at which the fusible member melts

Question 58

What is the most common metering device on a reciprocating system?

Thermostatic expansion valve

Automatic expansion valve

Orifice

Capillary tube

Answer 58

Thermostatic expansion valve

Question 59

If the city water is too expensive, you can use water from:

Well

Lake

All answers are correct

River

Answer 59

All answers are correct

Question 60

If R134 contact your skin, what would you do?

Nothing, it is HFC

Use body oil on skin

Flush with water until removed

Make sure you have proper air movement over skin to evaporate

Answer 60

Flush with water until removed

Question 61

The orifice plate meters the refrigerant. What else can be said about the vessel that contains the orifice plate?

It is a vapor recycler

It cleans the refrigerant

It economizes

It acts as a condenser for subcooling

Answer 61

It economizes

Question 62

The sole refrigeration engineer on duty in a building is permitted to leave the building refrigeration system is in operation only when

Lunch or dinner occur

System is in automatic operation

Relieved by another licensed refrigeration engineer

The assistant provides coverage or supervision

Answer 62

Relieved by another licensed refrigeration engineer

Question 63

When changing water to ice, what must be removed?

Specific heat

Latent heat

Sensible heat

N/A

Answer 63

Latent heat

Question 64

Vice-President of operations comes in on a cold winter day and ask the RMO to go shovel snow. What should he do?

Obey the manger and go out and shovel snow with radio communication

As long as you check in every 45 minutes

Do not go out and shovel snow until another licensed engineer relieves you

Call the union shop and fill out a report, but shovel snow

Answer 64

Do not go out and shovel snow until another licensed engineer relieves you