Refrigerant Machine Operator Test

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  • 1/100 Questions

    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
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About This Quiz

Industrial refrigerant machine operators seem to be simple people within the production chain but essentially are very important. Take up the quiz below and see how good you are as a refrigerant machine operator. All the best.

Refrigerant Machine Operator Test - Quiz

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  • 2. 

    CONVERT 18" VACUUM TO PSIA

    • 7.7

    • 0.6

    • 5.9

    • 23.5

    Correct Answer
    A. 5.9
  • 3. 

    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

    Correct Answer
    A. FROST MAY DEVELOP IN THE SUCTION LINE
    Explanation
    If the compressor is receiving liquid, it can cause the refrigerant to become over-cooled and result in frost formation in the suction line. This is because the liquid refrigerant will cause a drop in temperature in the suction line, leading to condensation and subsequent frost formation. This can be a sign of liquid refrigerant entering the compressor, which is undesirable as it can lead to damage and decreased efficiency of the compressor and the entire refrigeration system.

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  • 4. 

    WHAT REFRIGERANT SYSTEMS ARE MOST LIKELY TO LEAK REFRIGERANT IN BUILDING SPACES THAT ARE BEING COOLED?

    • INDIRECT SYSTEMS

    • DIRECT SYSTEMS

    • INDIRECT CLOSED SYSTEMS

    • INDRIECT OPEN SYSTEMS

    Correct Answer
    A. DIRECT SYSTEMS
    Explanation
    Direct systems are most likely to leak refrigerant in building spaces that are being cooled. This is because direct systems have a direct connection between the refrigerant and the building space, which increases the chances of leaks occurring. In contrast, indirect systems, both closed and open, have a separation between the refrigerant and the building space, reducing the likelihood of refrigerant leaks.

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  • 5. 

    AN OPERATOR HAS BEEN ASSIGNED TO A LARGE RECIPROCATING MACHINE WITHOUT UNLOADERS OF THE FOLLOWING SAFETY PROPER PROCEDURE FOR STARTING 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

    Correct Answer
    A. SUCTION VALVE AND DISCHARGE BYPASS BOTH OPEN
    Explanation
    The correct answer is "Suction valve and discharge bypass both open." This is the proper procedure for starting the machine without unloaders. By opening the suction valve, the machine will be able to draw in the necessary fluid. Opening the discharge bypass allows the fluid to bypass the machine until it is fully operational. This ensures a smooth start-up without causing any damage to the reciprocating machine.

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  • 6. 

    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 WOULD MOST LIKELY 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

    Correct Answer
    A. AN INCREASE IN COMPRESSOR HEAD PRESSURE
    Explanation
    An increase in compressor head pressure would be the first evidence of a failure to maintain water treatment in the condenser water. This is because when water treatment is not properly maintained, it can lead to the accumulation of impurities and deposits in the condenser. These impurities can restrict the flow of water through the condenser, causing an increase in head pressure in the compressor as it has to work harder to pump the refrigerant through the system.

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  • 7. 

    DURING A PARTICULAR ROUND AN OPERATOR NOTICES THAT THE SUCTION LINE AND PART OF THE COMPRESSOR ARE FROSTED, THE MOST LIKELY CAUSE OF THE CONDITION IS

    • NOT ENOUGH REFRIGERANT IN SYSTEM

    • EXPANSION VALVE OPEN TOO WIDE

    • THE COMPRESSOR IS RUNNING CONTINUALLY

    • COMPRESSOR VALVES ARE LEAKING

    Correct Answer
    A. EXPANSION VALVE OPEN TOO WIDE
    Explanation
    The most likely cause of the frost on the suction line and part of the compressor is that the expansion valve is open too wide. When the expansion valve is open too wide, it allows too much refrigerant to flow into the evaporator coil, causing the temperature to drop significantly. This can lead to the formation of frost on the suction line and compressor.

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  • 8. 

    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 °F OF

    • 80°F

    • 90°F

    • 110°F

    • 130°F

    Correct Answer
    A. 90°F
    Explanation
    Using warm water to increase the release rate of refrigerant from the drum is a common practice when charging an R-12 reciprocating refrigeration system. However, the water temperature should not exceed 90°F. If the water temperature is too high, it can cause the refrigerant to vaporize too quickly, leading to inefficient charging and potential damage to the system. Therefore, 90°F is the maximum temperature that should be used to ensure proper charging of the system.

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  • 9. 

    WITH RESPECT TO FIRE SAFETY, THE ANSI/ASHRAE REFRIGERANT SAFETY CLASSIFICATION THAT IS MOST DANGEROUS IS

    • A1

    • B2

    • A3

    • B1

    Correct Answer
    A. A3
    Explanation
    The correct answer is A3. In the ANSI/ASHRAE refrigerant safety classification, A3 refers to refrigerants that are flammable. Flammable refrigerants pose a higher risk in terms of fire safety compared to non-flammable refrigerants. They have a lower ignition point and can easily ignite if exposed to an ignition source. It is important to handle and store flammable refrigerants with caution to minimize the risk of fire accidents.

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  • 10. 

    AT THE CONDENSER, 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

    Correct Answer
    A. HIGH PRESSURE GAS AND LEAVES AS HIGH PRESSURE LIQUID
    Explanation
    The correct answer is high pressure gas and leaves as high pressure liquid. This is because the condenser is the component in a refrigeration system where the refrigerant gas is cooled and condensed into a liquid state. The high pressure gas enters the condenser and as it is cooled, it transitions into a high pressure liquid.

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  • 11. 

    ACCORDING TO NYC FIRE CODE CLASSIFICATION OF REFRIGERANT, AMMONIA WOULD FALL UNDER WHICH GROUP?

    • GROUP 1

    • GROUP 2

    • GROUP 3

    • GROUP 4

    Correct Answer
    A. GROUP 2
    Explanation
    According to the NYC Fire Code classification of refrigerants, ammonia would fall under Group 2.

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  • 12. 

    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

    Correct Answer
    A. INCREASE BY A FACTOR OF 2
    Explanation
    If an electric motor is rewound to cut resistance by 1/2, all other factors being equal, the motor power would increase by a factor of 2. This is because power is directly proportional to the square of the current passing through the motor. By reducing the resistance, the current passing through the motor would increase, resulting in a power increase. Since power is proportional to the square of the current, halving the resistance would double the current, leading to a power increase by a factor of 2.

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  • 13. 

    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

    Correct Answer
    A. OIL, WATER, REFRIGERANT
    Explanation
    When observing R-11, water, and lubricating oil together at 70°F, the fluids will settle in the container from top to bottom in the order of oil, water, and refrigerant. This is because oil has a higher density than water and refrigerant, causing it to settle at the bottom. Water, being less dense than oil but more dense than refrigerant, will settle above the oil layer. Refrigerant, being the least dense, will settle at the top of the container.

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  • 14. 

    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

    Correct Answer
    A. 1808
    Explanation
    Given the information that the reciprocating refrigeration compressor cylinder has a 12" bore and 16" stroke, we can calculate the volume of the cylinder using the formula for the volume of a cylinder, which is V = πr^2h.

    First, we need to find the radius of the cylinder, which is half of the bore. So, the radius would be 12"/2 = 6".

    Next, we need to find the height of the cylinder, which is the stroke. So, the height would be 16".

    Now, we can substitute these values into the formula to find the volume.

    V = π(6)^2(16) = 1808 cubic inches.

    Therefore, the volume of refrigerant in cubic inches would be closer to 1808.

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  • 15. 

    YOU HAVE BEEN INFORMED THAT THE O.A.T. HAS DROPPED 10°C.  THE TEMPERATURE IN °F IS

    • 32

    • 28

    • 40

    • 18

    Correct Answer
    A. 18
    Explanation
    The given question asks for the temperature in Fahrenheit after a drop of 10°C. To convert Celsius to Fahrenheit, we use the formula F = (C × 9/5) + 32. Plugging in the value of -10°C into the formula, we get (-10 × 9/5) + 32 = -18 + 32 = 14. Therefore, the correct answer is 18°F.

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  • 16. 

    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

    Correct Answer
    A. SYSTEMS OPERATING BELOW ATMOSPHERIC PRESSURE
    Explanation
    An automatic purge unit is required for refrigerating systems operating below atmospheric pressure because these systems are more prone to air and moisture ingress. Operating below atmospheric pressure creates a vacuum, which can cause air and moisture to leak into the system. The automatic purge unit helps to remove any air and moisture that enters the system, ensuring optimal performance and preventing damage to the system components.

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  • 17. 

    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

    Correct Answer
    A. AN ECONOMIZER
    Explanation
    Orifice plates may be used as a metering device component in a centrifugal system. The vessel in which they are contained can also serve as an economizer. An economizer is a device that recovers heat from the exhaust gases of a system and uses it to preheat the incoming fluid, thus reducing energy consumption. In this case, the vessel containing the orifice plates can act as an economizer by utilizing the heat from the system to preheat the fluid before it enters the centrifugal system, thereby saving energy.

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  • 18. 

    A RUPTURE DISC IN A CENTRIFUGAL REFRIGERATING MACHINE IS NORMALLY LOCATED ON THE

    • CONDENSER

    • ECONOMIZER

    • COMPRESSOR DISCHARGE

    • EVAPORATOR

    Correct Answer
    A. EVAPORATOR
    Explanation
    In a centrifugal refrigerating machine, a rupture disc is normally located on the evaporator. The evaporator is responsible for absorbing heat from the surroundings and allowing the refrigerant to evaporate. If there is an excessive pressure buildup in the evaporator, the rupture disc will burst, releasing the pressure and preventing any potential damage or accidents. Placing the rupture disc on the evaporator ensures that any pressure buildup is safely released before it reaches other components of the refrigerating machine.

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  • 19. 

    A PUMP AFFECTS THE PRESSURE OF A FLUID OR GAS BY: 

    • REDUCING PRESSURE

    • RAISING PRESSURE

    • REGULATING PRESSURE

    • STABILIZING PRESSURE

    Correct Answer
    A. RAISING PRESSURE
    Explanation
    A pump affects the pressure of a fluid or gas by raising it. When a pump is used, it creates a force that increases the pressure of the fluid or gas, pushing it to move from an area of lower pressure to an area of higher pressure. This process is commonly used in various applications such as pumping water, fuel, or air, where the pump raises the pressure to ensure the fluid or gas flows efficiently through a system or reaches a desired location.

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  • 20. 

    AN OPERATOR IS RUNNING TWO 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

    Correct Answer
    A. A REDUCTION IN TOTAL FLOW RATE TO CONDENSER
    Explanation
    If the operator throttles back on the discharge valve of the other pump, it would result in a reduction in the total flow rate to the condenser. This is because by throttling back on the discharge valve, the operator is restricting the flow of water from the pump, thereby reducing the overall flow rate to the condenser.

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  • 21. 

    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

    Correct Answer
    A. 1.2 OF DESIGN PRESSURE (AT LEAST)
    Explanation
    The correct answer is 1.2 of design pressure (at least) because when replacing the gauge on the high side of the refrigeration system, it is important to ensure that the new gauge can handle the pressure of the system. The pressure graduation rate should be at least 1.2 times the design pressure to provide a safety margin and prevent the gauge from rupturing. Additionally, the answer mentions that the rupture guard also needs to be replaced, indicating the need for a gauge that can handle high pressures. A compound gauge is suitable for this purpose as it can measure both positive and negative pressures.

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  • 22. 

    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

    Correct Answer
    A. ADDITIONAL REFRIGERANT BE CHARGED
    Explanation
    The correct answer is "ADDITIONAL REFRIGERANT BE CHARGED" because short cycling of the motor compressor in a refrigeration unit can be caused by a low refrigerant charge. When the refrigerant charge is low, the unit may not be able to maintain the proper pressure levels, causing the compressor to cycle on and off rapidly. Adding more refrigerant can help restore the proper charge and prevent short cycling. The other options mentioned, such as inspecting for a dirty TEV strainer, partially clogged discharge line, or checking compressor wiring, may also be necessary troubleshooting steps, but they are not specifically related to the issue of short cycling caused by low refrigerant charge.

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  • 23. 

    OF THE FOLLOWING THE MOST CORRECT WAY TO DESCRIBE A BRAZED JOINT IS

    • PRESSURE FITTING

    • GAS TIGHT FITTING

    • START TO MELT AT 400°F

    • START TO MELT AT 500°F

    Correct Answer
    A. GAS TIGHT FITTING
    Explanation
    A brazed joint is a type of joint that is created by heating two metal pieces and melting a filler metal into the joint. This process creates a strong and durable connection between the two pieces. The most correct way to describe a brazed joint is as a gas tight fitting. This is because the melted filler metal forms a solid bond between the two pieces, creating a seal that is resistant to gas or fluid leakage. The other options, such as pressure fitting or starting to melt at specific temperatures, do not accurately describe the nature of a brazed joint.

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  • 24. 

    YOU ARE AN RMO 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

    Correct Answer
    A. LOWER THE COMPRESSOR SUCTION OPERATING PRESSURE
    Explanation
    Lowering the compressor suction operating pressure will result in a colder water supply. When the suction pressure is lowered, the refrigerant entering the compressor will have a lower temperature, which will in turn result in a lower temperature of the water being produced. This adjustment is necessary to accommodate the increased attendance and temperature in the afternoon. Re-adjusting the TEV superheat setting, deactivating the freeze stat, or raising the compressor discharge operating pressure would not have the desired effect of producing a colder water supply.

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  • 25. 

    OF THE FOLLOWING THE MOST UNDESIRABLE PROPERTY IN REFRIGERANT IS

    • LOW CORRESPONDING COMPRESSOR DISCHARGE TEMP

    • LOW VISCOSITY

    • LOW LATENT HEAT

    • LOW CORRESPONDING OPERATING PRESSURE

    Correct Answer
    A. LOW LATENT HEAT
    Explanation
    Low latent heat is the most undesirable property in a refrigerant because it means that the refrigerant has a low capacity to absorb heat during the evaporation process. This results in a less efficient cooling system as the refrigerant is not able to remove as much heat from the surroundings. A refrigerant with a higher latent heat would be more desirable as it would be able to absorb more heat and provide better cooling capabilities.

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  • 26. 

    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.  OF THE FOLLOWING 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

    Correct Answer
    A. SCALE PARTICLES LODGED IN THE TEV VALVE
    Explanation
    The most likely cause for the significant increase in superheat temperature for the refrigerating fluid entering a reciprocating compressor is scale particles lodged in the TEV valve. Scale particles can restrict the flow of refrigerant through the valve, causing a decrease in the amount of refrigerant entering the compressor and leading to an increase in superheat temperature. This can negatively affect the efficiency and performance of the compressor and the overall plant operation.

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  • 27. 

    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

    Correct Answer
    A. FAULTY COMPRESSOR VALVES
    Explanation
    The cycling times being normal suggests that the overall operation of the reciprocating refrigerating unit is functioning properly. However, the abnormal readings of compressor compression and temperature indicate that there may be an issue with the compressor valves. Faulty compressor valves can cause inefficient compression and abnormal temperature readings. Therefore, inspecting for faulty compressor valves would be the appropriate service requirement in this situation.

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  • 28. 

    YOU ARE AN RMO ASSIGNED TO 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

    Correct Answer
    A. MUST ENSURE THE FLAME IS ENCLOSED AND VENTED TO OPEN AIR
    Explanation
    When working in a facility where the refrigerant has been changed from a flammable refrigerant to R-22, it is important to ensure safety while brazing metal. The correct answer states that the flame must be enclosed and vented to open air. This is necessary because R-22 is not a flammable refrigerant, so there is no risk of ignition. However, it is still crucial to enclose the flame and vent it to open air to prevent any potential hazards or accidents. This ensures that the brazing process is done safely and without any risk to the facility or personnel.

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  • 29. 

    A RMO NEEDED TO VARY THE FLOW OF REFRIGERANT IN A SYSTEM.  A CONTINUOUS VARIATION IN THE FLOW OF THE SYSTEM DOES NOT INCLUDE THE:

    • SOLENOID VALVE

    • HIGH SIDE FLOAT

    • THERMAL EXPANSION VALVE

    • CAPILLARY TUBE

    Correct Answer
    A. SOLENOID VALVE
    Explanation
    A solenoid valve is not capable of providing a continuous variation in the flow of refrigerant in a system. Solenoid valves are typically used to control the on/off function of the flow, rather than allowing for a continuous adjustment. In contrast, the other options listed - high side float, thermal expansion valve, and capillary tube - are all components that can be used to vary the flow of refrigerant in a system in a continuous manner.

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  • 30. 

    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

    Correct Answer
    A. OPENING THE SUCTION VALVES WITH SOME FORM OF CONTROL
    Explanation
    Capacity control in a reciprocating compressor is typically achieved by opening the suction valves with some form of control. By adjusting the suction valves, the amount of gas entering the compressor can be regulated, thereby controlling the capacity of the compressor. This allows for efficient operation and the ability to match the compressor's output to the required demand. Controlling the discharge pressure, changing the stroke and adding re-expansion volume, and returning the discharge gas to suction are not typically used methods for capacity control in a reciprocating compressor.

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  • 31. 

    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 5°F, 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

    Correct Answer
    A. LOWER COOLING WATER TEMPERATURE RETURN
    Explanation
    If the wet bulb temperature drops by 5°F while the dry bulb temperature remains constant, it indicates a decrease in the cooling tower temperature. Since the wet bulb temperature is a measure of the cooling tower's efficiency, a lower wet bulb temperature suggests that the cooling tower is able to cool the water more effectively. As a result, the operator should expect a lower cooling water temperature return.

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  • 32. 

    A RMO WOULD EXPECT A RELIEF VALVE TO START FUNCTIONING (FOR THE SECTION OF REFRIGERATING 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

    Correct Answer
    A. THE DESIGN PRESSURE
    Explanation
    A relief valve is designed to protect a refrigerating system by releasing excess pressure when it reaches a certain level. The design pressure is the specific pressure that the system is designed to handle without any damage or failure. Therefore, a RMO (Refrigeration Maintenance Operator) would expect the relief valve to start functioning at the design pressure, as this is the pressure that the system is intended to operate within. Starting the relief valve at any other pressure, such as 5% over design pressure or 20% below design pressure, could potentially cause damage to the system or prevent it from operating efficiently. The recommended operating pressure for normal cooling conditions may be a guideline, but the design pressure is the critical factor in determining when the relief valve should start functioning.

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  • 33. 

    A 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

    Correct Answer
    A. LOW PRESSURE SIDE OF THE EQUIPMENT
    Explanation
    The operator would most likely find the charging valve on the low pressure side of the equipment because when charging a refrigerant, it is typically done on the low pressure side to ensure proper flow and distribution of the refrigerant throughout the system. Charging on the high pressure side could lead to overcharging and potential damage to the equipment. The discharge side of the equipment is where the refrigerant exits the compressor, so it would not be the correct location for the charging valve. The receiver is a storage tank for the refrigerant and does not typically have a charging valve.

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  • 34. 

    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

    Correct Answer
    A. STOP WHEN PRESSURE CEASES TO DROP
    Explanation
    When properly purging, it is important to stop when the pressure ceases to drop. This means that all the air or gas that needed to be purged from the system has been successfully removed. Continuing to purge beyond this point would be unnecessary and could potentially lead to over-purging or damaging the system. Therefore, stopping when the pressure ceases to drop ensures that the purging process is completed efficiently and effectively.

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  • 35. 

    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

    Correct Answer
    A. AS HEAT OF EVAPORATION OF THE COOLING TOWER
    Explanation
    In a refrigeration system that includes a forced draft cooling tower, the heat that is removed from the building is finally rejected as heat of evaporation of the cooling tower. This means that the heat is transferred to the cooling tower, where it is used to evaporate water and remove heat from the system. The evaporated water is then released into the atmosphere, effectively rejecting the heat from the system. This is a common method of heat rejection in refrigeration systems that use cooling towers.

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  • 36. 

    WHICH IS NOT USED AS A COOLING MEDIUM IN AN INDIRECT SYSTEM

    • R-22

    • CALCIUM CHLORIDE

    • GLOCOL

    • SODIUM CHLORIDE

    Correct Answer
    A. R-22
    Explanation
    R-22 is not used as a cooling medium in an indirect system because it is a type of refrigerant that is commonly used in direct systems, such as air conditioning units and heat pumps. R-22 is not suitable for indirect systems because it can cause corrosion and damage to the components of the system. In indirect systems, other cooling mediums such as calcium chloride, glycol, and sodium chloride are used instead.

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  • 37. 

    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

    Correct Answer
    A. WATTS = VOLTS X AMPS X POWER FACTOR
    Explanation
    The correct answer is WATTS = VOLTS X AMPS X POWER FACTOR. In a refrigeration plant, the power consumption of a small induction refrigeration motor running on AC current can be determined by multiplying the voltage, current, and power factor. The power factor represents the efficiency of the motor and takes into account the phase difference between the voltage and current waveforms. By including the power factor in the calculation, the true power consumption of the motor can be accurately determined.

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  • 38. 

    OF THE FOLLOWING, WHICH REFRIGERANT REQUIRES THE APPROVAL FOR USE BY THE NYC FIRE DEPT?

    • R-22

    • R-12

    • CARBON DIOXIDE

    • BUTANE

    Correct Answer
    A. BUTANE
    Explanation
    Butane requires approval for use by the NYC Fire Department because it is a highly flammable refrigerant. The NYC Fire Department regulates the use of flammable substances to ensure the safety of the public and prevent potential fire hazards. Therefore, approval is necessary before butane can be used as a refrigerant in NYC.

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  • 39. 

    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

    Correct Answer
    A. THREE WAY VALVE
    Explanation
    A three-way valve is the correct choice when installing a service valve to isolate a dual pressure device while keeping the system in service. A three-way valve has three ports, allowing for the diversion of fluid flow between two different paths. In this case, one port can be used to connect to the dual pressure device, while the other two ports can be used to maintain the flow of fluid through the system. This configuration allows for the isolation of the dual pressure device without interrupting the operation of the system.

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  • 40. 

    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

    Correct Answer
    A. THE CLEARANCE SPACES IN THE CYLINDERS
    Explanation
    The solenoid unloaders on reciprocating compressors are designed to unload the clearance spaces in the cylinders. This means that when the compressor reaches a certain pressure, the solenoid unloaders will open, allowing the compressed air in the clearance spaces to escape. This unloading process helps to reduce the load on the compressor and prevent it from overworking. By unloading the clearance spaces, the compressor can operate more efficiently and effectively.

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  • 41. 

    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

    Correct Answer
    A. LOWER THE CONDENSER PRESSURE
    Explanation
    Lowering the condenser pressure results in a more efficient operation of a centrifugal compressor. This is because lowering the condenser pressure reduces the pressure difference between the condenser and the evaporator, which in turn reduces the work required by the compressor to compress the refrigerant. This leads to improved efficiency and energy savings in the refrigeration cycle.

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  • 42. 

    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

    Correct Answer
    A. HIGHER EVAPORATIVE TEMPERATURE AND HIGH CONDENSER TEMPERATURE
    Explanation
    The condition "Higher Evaporative Temperature and High Condenser Temperature" generally results in the greatest amount of heat in BTU per minute being absorbed by the condenser water. This is because the refrigerant in the cycle absorbs more heat due to the higher evaporative temperature and, despite high condenser temperatures potentially indicating less efficient heat transfer, the overall heat content being higher allows for more heat to be rejected to the condenser water.

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  • 43. 

    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

    Correct Answer
    A. GLOBE
    Explanation
    The operator should avoid the use of the globe valve because it typically has a higher pressure drop compared to the other options. Globe valves have a more restrictive flow path due to their design, which results in higher resistance and pressure drop. In contrast, ball, plug, and gate valves generally offer lower pressure drops, making them more suitable for minimizing pressure loss in a system.

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  • 44. 

    IN AN EMERGENCY IF YOU MUST DUMP REFRIGERANT INTO 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.

    Correct Answer
    A. YOU DISCHARGE UNDER THE SUPERVISION OF THE FIRE DEPT.
    Explanation
    In an emergency situation where it is necessary to dump refrigerant into a sewer, it is crucial to do so under the supervision of the fire department. This is because the fire department has the expertise and resources to ensure that the process is carried out safely and without causing harm to the environment or public health. Dumping refrigerant into a sewer without proper supervision can lead to contamination of water sources and pose a risk to the community. Therefore, it is essential to have the guidance and oversight of the fire department in such circumstances.

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  • 45. 

    DUE TO A COLD FRONT, THERE WAS A SHARP DROP IN O.A.T., THE MOST LIKELY EFFECT OF THIS CONDITION ON THE OPERATION OF THE RECIPROCATING MACHINE WOULD BE THAT THE THERMOSTAT CAUSES 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

    Correct Answer
    A. CLOSE, THE COMPRESSOR PUMPS DOWN AND SHUTS DOWN ON LOW PRESSURE
    Explanation
    A cold front causes a sharp drop in outside air temperature (O.A.T.). In this condition, the thermostat would cause the solenoid valve to close. As a result, the compressor would pump down the system and shut down on low pressure. This is the most likely effect because when the solenoid valve closes, it restricts the flow of refrigerant, causing the compressor to pump down the system and eventually shut down due to low pressure.

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  • 46. 

    A JET EJECTOR IS USED TO RAISE OIL MIXED WITH 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

    Correct Answer
    A. YOU WILL HAVE INSUFFICIENT HEAD TO LIFT THE OIL
    Explanation
    If the flow of oil is restricted, it means that there is a limitation or obstruction in the movement of oil. This restriction will result in insufficient head, which refers to the pressure or force required to lift the oil. Without enough head, the oil will not be able to be raised by the jet ejector. Therefore, the correct answer is "YOU WILL HAVE INSUFFICIENT HEAD TO LIFT THE OIL."

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  • 47. 

    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

    Correct Answer
    A. EXPANSION VALVES WILL NOT FEED PROPERLY
    Explanation
    When the condensing pressure is low, the liquid level in the condenser will fall too low. This can cause the expansion valves to not feed properly. The expansion valves are responsible for regulating the flow of refrigerant into the evaporator. If they do not feed properly, it can lead to inadequate cooling and inefficient operation of the system. Therefore, low condensing pressure is not ideal as it can result in improper functioning of the expansion valves.

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  • 48. 

    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

    Correct Answer
    A. INCREASE WITH THE VELOCITY OF THE WATER IN THE TUBES
    Explanation
    The heat transfer rate in the condenser is directly proportional to the velocity of the water in the tubes. As the velocity of the water increases, there is more turbulence and better mixing, which enhances the heat transfer process. Therefore, increasing the velocity of the water in the tubes will result in an increase in the heat transfer rate in the condenser.

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  • 49. 

    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

    Correct Answer
    A. YOU CAN FREEZE WATER IN THE TUBES WITH LIQUID
    Explanation
    Charging with liquid can cause water in the tubes to freeze. This can lead to blockages and reduced efficiency in the system. Charging with vapor, on the other hand, allows for a controlled flow of refrigerant without the risk of freezing water in the tubes.

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Quiz Review Timeline (Updated): Apr 16, 2024 +

Our quizzes are rigorously reviewed, monitored and continuously updated by our expert board to maintain accuracy, relevance, and timeliness.

  • Current Version
  • Apr 16, 2024
    Quiz Edited by
    ProProfs Editorial Team
  • Aug 28, 2018
    Quiz Created by
    Todd

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