Refrigerant Machine Operator Practice Test #4 Flashcards by Christine Banker

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

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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

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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

Low pressure control

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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

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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

A hydraulic governor assembly

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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

Altering the size of the passage wheel

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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

Produce large amounts of subcooling

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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.

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.

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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

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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

Front seated

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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

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

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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

A decrease in space temperature

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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

To compensate for axial thrust

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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

Return oil to the compressor

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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:

64.4

70.4

30.3

70.4

1 psi = 2.036 inches of mercury

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

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.

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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

This is incorrect and would starve the cooling coil

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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

Distance between the top of the rotating blades and the casing

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What is the cooling medium of the cooling towers?

Air

Water

Air and water

Fan

Air

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Types of steam turbines include all of the following except:

Impulse steam turbines

Reaction steam turbines

Impulse reaction steam turbine

None of the above

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Mechanical seals are typically made of:

Carbon and stainless steel

Ceramic and carbon

Ceramic and graphite

Graphite impregnated rope or string

Carbon and stainless steel

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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

A point to point detail of how the wires are run

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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

Graphite impregnated rope or string

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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

Create a vacuum

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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

All of the above

An automatic purge unit is required on units: With centrifugal compressors Containing low pressure refrigerants Absorption systems Double indirect open spray systems

Containing low pressure refrigerants

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

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

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

Wherever the shaft emerges from the casing or steam could leak

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

Refrigerant undercharge

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

Suction and discharge lines perpendicular to each other

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

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

The medium/mediums for cooling in an evaporative condenser is/are: Air only Refrigerant and water Water and air Glycol and air

Water and air

What is the most used regulation book in the U.S. used by the RMO? NFPA USEPA Federal Regulation book NYC building code

USEPA

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

330 lbs of refrigerant

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

"A" is producing four tons and "B" is producing three tons 1 ton of refrigerant is = 12000 BTU's per hour

What is the diaphragm of the power assembly of a TEV made of? Copper Flexible rubber Flexible steel N/A

Flexible steel

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

Burnt out crankcase heater

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

Oil to leave the trap and return to the compressor

A valve that will not provide continuos flow of refrigerant through the circuit is the: Globe valve Service valve Solenoid valve TXV

Solenoid valve

The recirculation valve on a surface condenser is controlled by the: Hot well level control The condensate pumps pneumatic controller Oil pump pressure

Hot well level control

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

Prevent damage to turbine blades

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

Low temperature vapor in and high temperature vapor out

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

Back to the hot well for priming

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

Vacuum pump

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

Will increase as the velocity goes up

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

Rejected as latent and sensible heat heat to the ambient air

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

Pumping it into the compressor crankcase

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

Valve plunger will lift off the seat

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

Once per shift

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

Open the petcock and bleed air from volute

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

With electric current in a coil causing the plunger to lift

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

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

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

Compressor crankcase

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

Scale particles lodged in the TEV

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

Vent the mixture to the outside air

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

Reduce friction in the compressor parts

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

Temperature at which the fusible member melts

What is the most common metering device on a reciprocating system? Thermostatic expansion valve Automatic expansion valve Orifice Capillary tube

Thermostatic expansion valve

If the city water is too expensive, you can use water from: Well Lake All answers are correct River

All answers are correct

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

Flush with water until removed

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

It economizes

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

Relieved by another licensed refrigeration engineer

When changing water to ice, what must be removed? Specific heat Latent heat Sensible heat N/A

Latent heat

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

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

Refrigerant Machine Operator Practice Test #4 Flashcards

(64 cards)