Refrigerant Machine Operator License Exam Prep Test
Below is a quiz on the refrigerant machine operator! It is designed to help an operator review all that they know about fridges and how to correct any defaults they may be experiencing. How about you give it a shot and get to see if all you know is enough to provide you with the certification. All the best of luck!
- 1.
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:
- A.
DAMAGE TO FAN BLADES
- B.
INCREASE IN COOLING TOWER WATER TEMP BEING RETURNED
- C.
DECREASE IN MAKEUP WATER REQUIREMENTS
- D.
A DROP IN WET BULB TEMP
Correct Answer
B. INCREASE IN COOLING TOWER WATER TEMP BEING RETURNEDExplanation
If the eliminator plates located below the fan in an induced draft-cooling tower have become clogged, it would most likely result in an increase in cooling tower water temperature being returned. The eliminator plates are responsible for removing water droplets from the air leaving the cooling tower. If they become clogged, the water droplets will not be effectively removed, leading to a higher water temperature being returned to the cooling tower. This can negatively impact the cooling efficiency of the tower and potentially cause other issues in the cooling system.Rate this question:
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- 2.
SUPERHEATED VAPOR PROTECTS THE COMPRESSOR AGAINST LIQUID INTAKE. WHAT WOULD THE RMO NOTICE IF COMPRESSOR WAS RECEIVING LIQUID?
- A.
HEAD PSI DROPPING TO LOW
- B.
DECREASE THE CAPACITY OF THE COMPRESSOR AND REFRIGERATION SYSTEM
- C.
NON-CONDENSABLES ARE MORE PRONE TO COLLECT IN THE SYSTEM
- D.
FROST MAY DEVELOP IN THE SUCTION LINE
Correct Answer
D. FROST MAY DEVELOP IN THE SUCTION LINEExplanation
If the compressor was receiving liquid, the RMO (Refrigeration Machine Operator) would notice that frost may develop in the suction line. This is because when liquid enters the compressor, it can cause a drop in temperature and lead to the formation of frost in the suction line. This is a sign of potential damage to the compressor and can decrease the efficiency of the refrigeration system.Rate this question:
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- 3.
WHAT REFRIGERANT SYSTEMS ARE MOST LIKELY TO LEAK REFRIGERANT IN BUILDING SPACES THAT ARE BEING COOLED?
- A.
INDIRECT SYSTEMS
- B.
DIRECT SYSTEMS
- C.
INDIRECT CLOSED SYSTEMS
- D.
INDRIECT OPEN SYSTEMS
Correct Answer
B. DIRECT SYSTEMSExplanation
Direct systems are most likely to leak refrigerant in building spaces that are being cooled. This is because direct systems have direct contact between the refrigerant and the building space being cooled, which increases the chances of leaks occurring. In contrast, indirect systems have a separate closed loop for the refrigerant, reducing the likelihood of leaks.Rate this question:
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- 4.
AN OPERATOR HAS BEEN ASSIGNED TO A LARGE RECIPROCATING MACHINE WITHOUT UNLOADERS OF THE FOLLOWING SAFETY PROPER PROCEDURE FOR STARTING MACHINE IS.
- A.
FILTER SUCTION AND DISCHARGE VALVES
- B.
SUCTION VALVE AND DISCHARGE BYPASS BOTH OPEN
- C.
SUCTION BYPASS AND DISCHARGE VALVE BOTH OPEN
- D.
DISCHARGE BYPASS AND SUCTION VALVE BOTH CLOSED
Correct Answer
B. SUCTION VALVE AND DISCHARGE BYPASS BOTH OPENExplanation
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 can draw in the necessary fluid. By opening the discharge bypass, the fluid can bypass the machine until it reaches the desired pressure or flow rate. This allows the machine to start up safely and prevents any damage or overload to the reciprocating machine.Rate this question:
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- 5.
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:
- A.
DECREASE IN SUPER HEAT TEMP ENTERING COMPRESSOR
- B.
AN INCREASE IN COMPRESSOR HEAD PRESSURE
- C.
AN INCREASE IN THE FLOW RATE OF NONCONDENSABLES
- D.
CONDENSER TO METERING DEVICE FROZEN
Correct Answer
B. AN INCREASE IN COMPRESSOR HEAD PRESSUREExplanation
Upon being assigned to a facility during inspection, if there has been a failure to maintain water treatment, the first evidence that would most likely be observed when inspecting the condenser water is an increase in compressor head pressure. This is because the failure to maintain water treatment can lead to the accumulation of contaminants in the condenser water, which can reduce the efficiency of heat transfer. As a result, the compressor needs to work harder to maintain the desired pressure, leading to an increase in head pressure.Rate this question:
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- 6.
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
- A.
NOT ENOUGH REFRIGERANT IN SYSTEM
- B.
EXPANSION VALVE OPEN TOO WIDE
- C.
THE COMPRESSOR IS RUNNING CONTINUALLY
- D.
COMPRESSOR VALVES ARE LEAKING
Correct Answer
B. EXPANSION VALVE OPEN TOO WIDEExplanation
The most likely cause of the frost formation on the suction line and 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 through the evaporator coil, causing the evaporator coil to become too cold. This can lead to frost formation on the suction line and compressor.Rate this question:
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- 7.
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
- A.
80°F
- B.
90°F
- C.
110°F
- D.
130°F
Correct Answer
B. 90°FExplanation
When charging an R-12 reciprocating refrigeration system, using warm water can increase the release rate of refrigerant from the drum. 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 unstable charging and potential damage to the system. Therefore, it is important to use warm water within the specified temperature range to ensure safe and effective charging of the system.Rate this question:
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- 8.
WITH RESPECT TO FIRE SAFETY, THE ANSI/ASHRAE REFRIGERANT SAFETY CLASSIFICATION THAT IS MOST DANGEROUS IS
- A.
A1
- B.
B2
- C.
A3
- D.
B1
Correct Answer
C. A3Explanation
The correct answer is A3. In terms of fire safety, the ANSI/ASHRAE refrigerant safety classification that is most dangerous is A3. Refrigerants classified as A3 are highly flammable and can pose a significant fire hazard if not handled properly. It is important to take appropriate precautions and follow safety guidelines when working with A3 refrigerants to minimize the risk of fire accidents.Rate this question:
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- 9.
AT THE CONDENSER, REFRIGERANT ENTERS AS
- A.
HIGH PRESSURE GAS AND LEAVES AS LOW PRESSURE LIQUID
- B.
HIGH PRESSURE GAS AND LEAVES AS HIGH PRESSURE LIQUID
- C.
SUPERHEATED GAS AND LEAVES AS HIGH TEMPERATURE LIQUID
- D.
HIGH TEMPERATURE GAS AND LEAVES AS SUPERHEATED GAS
Correct Answer
B. HIGH PRESSURE GAS AND LEAVES AS HIGH PRESSURE LIQUIDExplanation
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, in its gaseous state and under high pressure, releases heat and condenses into a high-pressure liquid. This high-pressure liquid is then sent to the expansion valve to continue the refrigeration cycle.Rate this question:
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- 10.
ACCORDING TO NYC FIRE CODE CLASSIFICATION OF REFRIGERANT, AMMONIA WOULD FALL UNDER WHICH GROUP?
- A.
GROUP 1
- B.
GROUP 2
- C.
GROUP 3
- D.
GROUP 4
Correct Answer
B. GROUP 2Explanation
Ammonia would fall under Group 2 according to the NYC Fire Code classification of refrigerant. This means that it is classified as a moderately hazardous material.Rate this question:
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- 11.
IF AN ELECTRIC MOTOR IS REWOUND TO CUT RESISTANCE BY 1/2, ALL OTHER FACTORS BEING EQUAL, THE MOTOR POWER WOULD:
- A.
REDUCE BY 1/2
- B.
INCREASE BY A FACTOR OF 2
- C.
STAY THE SAME
- D.
INCREASE BY A FACTOR OF 4
Correct Answer
B. INCREASE BY A FACTOR OF 2Explanation
When an electric motor is rewound to cut resistance by 1/2, it means that the resistance in the motor circuit has been reduced. Since power is directly proportional to the square of the current and inversely proportional to the resistance, reducing the resistance by 1/2 will result in a doubling of the current. As a result, the power of the motor will increase by a factor of 2.Rate this question:
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- 12.
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?
- A.
WATER, OIL, REFRIGERANT
- B.
OIL, REFRIGERANT, WATER
- C.
REFRIGERANT, OIL, WATER
- D.
WATER, REFRIGERANT, OIL
Correct Answer
D. WATER, REFRIGERANT, OILExplanation
Water, being denser than the refrigerant, would settle at the bottom. The refrigerant would occupy the middle layer, and the lubricating oil, being less dense than both, would float on top. Therefore, the correct order is water, refrigerant, and then oil.Rate this question:
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- 13.
A RECIPROCATING REFRIGERATION COMPRESSOR CYLINDER HAS A 12" BORE AND 16" STROKE, THE VOLUME OF REFRIGERANT IN CUBIC INCHES WOULD BE CLOSER TO
- A.
1204
- B.
1002
- C.
1808
- D.
1406
Correct Answer
C. 1808Explanation
The volume of a cylinder can be calculated using the formula V = πr^2h, where V is the volume, r is the radius, and h is the height. In this case, the radius is half of the bore, so it is 6 inches. The height is the stroke, so it is 16 inches. Plugging these values into the formula, we get V = π(6^2)(16) = 1808 cubic inches. Therefore, the volume of refrigerant in cubic inches would be closer to 1808.Rate this question:
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- 14.
YOU HAVE BEEN INFORMED THAT THE O.A.T. HAS DROPPED 10°C. THE TEMPERATURE IN °F IS
- A.
32
- B.
28
- C.
40
- D.
18
Correct Answer
D. 18Explanation
To convert Celsius to Fahrenheit, we use the formula F = (C x 9/5) + 32. In this case, the temperature dropped by 10°C. Plugging in the value into the formula, we get F = (10 x 9/5) + 32 = 18. Therefore, the temperature in °F is 18.Rate this question:
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- 15.
AN AUTOMATIC PURGE UNIT IS REQUIRED FOR THOSE REFRIGERATING SYSTEMS THAT HAVE
- A.
DOUBLE INDIRECT OPEN SPACE SYSTEMS
- B.
SYSTEMS OPERATING BELOW ATMOSPHERIC PRESSURE
- C.
ABSORPTION COMPRESSORS
- D.
OUTSIDE AIR DAMPERS
Correct Answer
B. SYSTEMS OPERATING BELOW ATMOSpHERIC PRESSUREExplanation
An automatic purge unit is required for refrigerating systems operating below atmospheric pressure. This is because when a system operates below atmospheric pressure, there is a higher likelihood of air and moisture entering the system. The automatic purge unit helps to remove any air and moisture that may have entered the system, ensuring the system operates efficiently and effectively.Rate this question:
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- 16.
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
- A.
VAPOR RECYCLING UNIT
- B.
AN ECONOMIZER
- C.
REFRIGERANT CLEANER
- D.
EVAPORATOR
Correct Answer
B. AN ECONOMIZERExplanation
Orifice plates can 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 preheats the feedwater by utilizing the waste heat from the flue gases before they are discharged to the atmosphere. This helps in improving the overall efficiency of the system by reducing the energy required for heating the feedwater. Therefore, in this context, the vessel containing the orifice plates can also function as an economizer.Rate this question:
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- 17.
A RUPTURE DISC IN A CENTRIFUGAL REFRIGERATING MACHINE IS NORMALLY LOCATED ON THE
- A.
CONDENSER
- B.
ECONOMIZER
- C.
COMPRESSOR DISCHARGE
- D.
EVAPORATOR
Correct Answer
D. EVAPORATORExplanation
A rupture disc in a centrifugal refrigerating machine is normally located on the evaporator. The evaporator is responsible for absorbing heat from the surroundings and turning the refrigerant into a low-pressure gas. If there is a sudden increase in pressure or a malfunction in the system, the rupture disc on the evaporator will burst, allowing the excess pressure to be released and preventing any damage to the machine. This ensures the safety and proper functioning of the refrigerating machine.Rate this question:
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- 18.
A PUMP AFFECTS THE PRESSURE OF A FLUID OR GAS BY:
- A.
REDUCING PRESSURE
- B.
RAISING PRESSURE
- C.
REGULATING PRESSURE
- D.
STABILIZING PRESSURE
Correct Answer
B. RAISING PRESSUREExplanation
A pump affects the pressure of a fluid or gas by raising the pressure. When a pump is used, it applies force to the fluid or gas, increasing its pressure. This is typically done by increasing the velocity of the fluid or gas and then converting that velocity into pressure. As a result, the pressure of the fluid or gas is raised, allowing it to flow or be used in various applications.Rate this question:
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- 19.
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.
A REDUCTION ON BOTH THE WATER FLOW RATE AND PRESSURE INTO THE CONDENSER
- B.
A REDUCTION IN TOTAL FLOW RATE TO CONDENSER
- C.
A REDUCTION IN WATER PRESSURE AT THE CONDENSER INLET
- D.
FOR THE PUMPS TO COMPENSATE TO MAINTAIN BOTH THE FLOW RATE AND DISCHARGE PRESSURE
Correct Answer
B. A REDUCTION IN TOTAL FLOW RATE TO CONDENSERExplanation
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 valve, the operator is restricting the flow of water from the pump, thereby reducing the overall flow rate.Rate this question:
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- 20.
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
- A.
1.2 OF DESIGN PRESSURE (AT LEAST)
- B.
THE RUPTURE GUARD HAS TO BE REPLACED ALSO
- C.
THE GAUGE HAS TO BE A COMPOUND GAUGE
- D.
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). This means that the pressure graduation rate of the new gauge should be at least 1.2 times the design pressure of the refrigeration system. This ensures that the gauge can accurately measure the pressure within the system and can handle the maximum pressure that the system is designed for. By replacing the gauge with one that meets this requirement, the RMO in charge can ensure the safe and efficient operation of the refrigeration system.Rate this question:
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- 21.
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
- A.
INSPECTION SHOULD BE MADE FOR DIRTY TEV STRAINER
- B.
PARTIALLY CLOGGED DISCHARGE LINE
- C.
CHECK COMPRESSOR WIRING, FOR OVERLOADED EQUIPMENT
- D.
ADDITIONAL REFRIGERANT BE CHARGED
Correct Answer
D. ADDITIONAL REFRIGERANT BE CHARGEDExplanation
The correct answer suggests that when a refrigeration unit with a low side float valve is experiencing short cycling of the motor compressor, the operator should consider adding additional refrigerant. This is because short cycling can be caused by a low refrigerant charge, which leads to inadequate cooling and causes the compressor to turn on and off frequently. By adding more refrigerant, the system can achieve the proper charge and prevent short cycling.Rate this question:
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- 22.
OF THE FOLLOWING THE MOST CORRECT WAY TO DESCRIBE A BRAZED JOINT IS
- A.
PRESSURE FITTING
- B.
GAS TIGHT FITTING
- C.
START TO MELT AT 400°F
- D.
START TO MELT AT 500°F
Correct Answer
B. GAS TIGHT FITTINGExplanation
A brazed joint is a type of joint that is created by joining two pieces of metal using a filler metal that has a lower melting point than the base metals. The filler metal is heated and melted, and then it flows into the joint, creating a strong and durable bond. The most correct way to describe a brazed joint is as a gas tight fitting because the process of brazing creates a joint that is sealed and leak-proof, making it suitable for applications where a tight seal is required.Rate this question:
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- 23.
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.
- A.
RE-ADJUST THE TEV SUPERHEAT SETTING
- B.
DEACTIVATE THE FREEZE STAT
- C.
RAISE THE COMPRESSOR DISCHARGE OPERATING PRESSURE
- D.
LOWER THE COMPRESSOR SUCTION OPERATING PRESSURE
Correct Answer
D. LOWER THE COMPRESSOR SUCTION OPERATING PRESSUREExplanation
To produce colder water supply, the RMO should lower the compressor suction operating pressure. By reducing the suction pressure, the compressor will draw in less heat from the surrounding air, resulting in a colder water supply. Re-adjusting the TEV superheat setting, deactivating the freeze stat, or raising the compressor discharge operating pressure would not directly affect the temperature of the water supply.Rate this question:
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- 24.
OF THE FOLLOWING THE MOST UNDESIRABLE PROPERTY IN REFRIGERANT IS
- A.
LOW CORRESPONDING COMPRESSOR DISCHARGE TEMP
- B.
LOW VISCOSITY
- C.
LOW LATENT HEAT
- D.
LOW CORRESPONDING OPERATING PRESSURE
Correct Answer
C. LOW LATENT HEATExplanation
Low latent heat is the most undesirable property in a refrigerant because latent heat is the amount of heat energy absorbed or released during a phase change, such as during the evaporation or condensation process in a refrigeration cycle. A low latent heat means that the refrigerant will absorb or release less heat energy during these phase changes, which will result in poor cooling efficiency. This will require the compressor to work harder and consume more energy to achieve the desired cooling effect, making it less efficient and cost-effective.Rate this question:
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- 25.
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
- A.
SCALE PARTICLES LODGED IN THE TEV VALVE
- B.
UNRAVELING OF THE INSULATION PROTECTING THE TEV VALVE THERMAL BULB
- C.
BUILD-UP OF NONCONDENSABLES IN THE CONDENSER
- D.
OVERCHARGE OF REFRIGERANT
Correct Answer
A. SCALE PARTICLES LODGED IN THE TEV VALVEExplanation
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 obstruct the flow of refrigerant and disrupt the normal operation of the thermal expansion valve (TEV), leading to improper regulation of the refrigerant flow and an increase in superheat temperature. This can result in inefficient cooling and potential damage to the compressor.Rate this question:
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- 26.
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
- A.
FAULTY MACHINE CONTROL
- B.
PROPER REFRIGERATION CHARGE
- C.
FAULTY COMPRESSOR VALVES
- D.
POOR CONDENSER OPERATION / DIRTY TUBES
Correct Answer
C. FAULTY COMPRESSOR VALVESExplanation
Based on the information given, the cycling times of the reciprocating refrigerating unit are normal, but the compressor compression and temperature readings are outside the normal rate. This suggests that there may be an issue with the compressor valves. Faulty compressor valves can cause abnormal compression and temperature readings, indicating a problem with the valves' ability to properly control the flow of refrigerant. Therefore, inspecting for faulty compressor valves would be the appropriate service requirement in this situation.Rate this question:
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- 27.
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:
- A.
MUST ENSURE THE FLAME IS ENCLOSED AND VENTED TO OPEN AIR
- B.
MAY MAKE REPAIRS AT LEAST 25 FEET FROM THE REFRIGERANT UNIT
- C.
MAY MAKE REPAIRS WITHOUT ANY RESTRICTIONS IF THE REFRIGERATING UNIT IS SHUT DOWN
- D.
MAY NOT MAKE REPAIR UNDER ANY CIRCUMSTANCES
Correct Answer
A. MUST ENSURE THE FLAME IS ENCLOSED AND VENTED TO OPEN AIRExplanation
When working in a facility where the refrigerant has been changed to R-22, it is important to ensure safety when brazing metal. The correct answer states that the flame must be enclosed and vented to open air. This means that any flame used during the repair process should be contained within a safe enclosure and any fumes or gases produced should be vented to the open air. This is crucial to prevent any potential ignition or release of flammable gases that may be present due to the change in refrigerant. It prioritizes safety and minimizes the risk of accidents or hazards.Rate this question:
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- 28.
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:
- A.
SOLENOID VALVE
- B.
HIGH SIDE FLOAT
- C.
THERMAL EXPANSION VALVE
- D.
CAPILLARY TUBE
Correct Answer
A. SOLENOID VALVEExplanation
The solenoid valve is not capable of providing a continuous variation in the flow of refrigerant in a system. It can only be either fully open or fully closed, resulting in a binary on/off flow. Therefore, it is not included in the options for a continuous variation in flow.Rate this question:
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- 29.
AN OPERATOR HAS BEEN ASSIGNED TO RUN A RECIPROCATING COMPRESSOR. THE FOLLOWING ACTION CAPACITY CONTROL WOULD MOST LIKELY BE ACHIEVED THROUGH:
- A.
OPENING THE SUCTION VALVES WITH SOME FORM OF CONTROL
- B.
CONTROLLING THE DISCHARGE PRESSURE
- C.
CHANGING THE STROKE AND ADDING RE-EXPANSION VOLUME
- D.
RETURNING THE DISCHARGE GAS TO SUCTION
Correct Answer
A. OPENING THE SUCTION VALVES WITH SOME FORM OF CONTROLExplanation
The action of capacity control in a reciprocating compressor is most likely achieved by opening the suction valves with some form of control. By adjusting the opening of the suction valves, the amount of gas entering the compressor can be controlled, thus regulating the capacity of the compressor. This allows for flexibility in matching the compressor's output to the required demand, ensuring efficient operation.Rate this question:
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- 30.
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:
- A.
HIGH COOLING WATER BEING RETURNED
- B.
RISE IN CONDENSER HEAD PRESSURE
- C.
LOWER COOLING WATER TEMPERATURE RETURN
- D.
NO NOTICEABLE EFFECT OF THE COOLING TOWER TEMP BEING RETURNED
Correct Answer
C. LOWER COOLING WATER TEMPERATURE RETURNExplanation
If the wet bulb temperature drops by 5°F while the dry bulb temperature remains constant, it indicates a decrease in the amount of moisture in the air. This decrease in moisture will result in a lower cooling water temperature return. As the air becomes drier, it will have less of a cooling effect on the water, causing a lower temperature return. Therefore, the operator should expect to see a lower cooling water temperature return in this scenario.Rate this question:
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- 31.
A RMO WOULD EXPECT A RELIEF VALVE TO START FUNCTIONING (FOR THE SECTION OF REFRIGERATING SYSTEM BEING PROTECTED) AT A PRESSURE MOST CLOSEST TO:
- A.
5% OVER DESIGN PRESSURE
- B.
THE DESIGN PRESSURE
- C.
RECOMMENDED OPERATING PRESSURE FOR NORMAL COOLING CONDITIONS
- D.
20% BELOW DESIGN PRESSURE
Correct Answer
B. THE DESIGN PRESSUREExplanation
A relief valve is designed to protect a refrigerating system from excessive pressure. It is set to open and release the excess pressure when it reaches a certain threshold. The design pressure is the maximum pressure that the system is designed to safely handle. Therefore, a RMO (Refrigeration Maintenance Operator) would expect the relief valve to start functioning at the design pressure, as this is the point where the system is at risk of being damaged or compromised.Rate this question:
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- 32.
CONVERT 18" VACUUM TO PSIA
- A.
7.7
- B.
0.6
- C.
8.85
- D.
23.5
Correct Answer
C. 8.85Explanation
The conversion of 18 inches of vacuum to psia is approximately 8.85. This is determined by applying the conversion factor of 1 psi being equivalent to approximately 2.036 inches of mercury. Therefore, 18 inches of vacuum corresponds to around 8.85 psia.Rate this question:
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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:
- A.
HIGH PRESSURE SIDE OF THE EQUIPMENT
- B.
LOW PRESSURE SIDE OF THE EQUIPMENT
- C.
DISCHARGE SIDE OF THE EQUIPMENT
- D.
RECIEVER
Correct Answer
B. LOW PRESSURE SIDE OF THE EQUIPMENTExplanation
The charging valve for the R-134A refrigerant is most likely to be found on the low pressure side of the equipment. This is because the low pressure side is where the refrigerant enters the system and is typically where charging is done. Charging the refrigerant on the low pressure side ensures that the correct amount of refrigerant is added to the system and helps maintain the proper functioning of the equipment.Rate this question:
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- 34.
WHEN PROPERLY PURGING YOU SHOULD
- A.
PURGE AT RAPID RATE
- B.
PURGE WITH COMPRESSOR ON
- C.
STOP WHEN PRESSURE CEASES TO DROP
- D.
RUN THE CONDENSER AS MUCH AS POSSIBLE
Correct Answer
C. STOP WHEN PRESSURE CEASES TO DROPExplanation
When properly purging, you should stop when the pressure ceases to drop. This means that all the unwanted gases or contaminants have been successfully removed from the system. Continuing to purge beyond this point would be unnecessary and a waste of time and resources.Rate this question:
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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:
- A.
AS HEAT OF EVAPORATION OF THE COOLING TOWER
- B.
IN THE ECONOMIZER
- C.
IN THE EVAPORATOR
- D.
CONDENSER WATER OUTLET
Correct Answer
A. AS HEAT OF EVAPORATION OF THE COOLING TOWERExplanation
The correct answer is "AS HEAT OF EVAPORATION OF THE COOLING TOWER". In a refrigeration system with a forced draft cooling tower, the cooling tower removes heat from the building by evaporating water. As the water evaporates, it absorbs heat from the building, effectively cooling it down. This heat is then rejected into the atmosphere, making the heat of evaporation of the cooling tower the final destination for the heat removed from the building.Rate this question:
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- 36.
WHICH IS NOT USED AS A COOLING MEDIUM IN AN INDIRECT SYSTEM
- A.
R-22
- B.
CALCIUM CHLORIDE
- C.
GLOCOL
- D.
SODIUM CHLORIDE
Correct Answer
A. R-22Explanation
R-22 is not used as a cooling medium in an indirect system. R-22 is a hydrochlorofluorocarbon (HCFC) refrigerant that was commonly used in air conditioning and refrigeration systems. However, due to its harmful effects on the ozone layer, its production and use have been phased out in many countries. In indirect cooling systems, other cooling mediums such as calcium chloride, glycol, or sodium chloride are used instead.Rate this question:
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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:
- A.
WATTS = VOLTS X AMPS X OHMS
- B.
WATTS = VOLTS X AMPS X HERTZ
- C.
WATTS = VOLTS X AMPS
- D.
WATTS = VOLTS X AMPS X POWER FACTOR
Correct Answer
D. WATTS = VOLTS X AMPS X POWER FACTORExplanation
The correct answer is WATTS = VOLTS X AMPS X POWER FACTOR. This formula is used to determine the true power consumption in a refrigeration plant when a small induction refrigeration motor is running on AC current. The power consumption is calculated by multiplying the voltage, current, and power factor. The power factor takes into account the phase difference between the voltage and current waveforms and represents the efficiency of the motor in converting electrical power into useful work. Therefore, including the power factor in the formula provides a more accurate measurement of the true power consumption.Rate this question:
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- 38.
OF THE FOLLOWING, WHICH REFRIGERANT REQUIRES THE APPROVAL FOR USE BY THE NYC FIRE DEPT?
- A.
R-22
- B.
R-12
- C.
CARBON DIOXIDE
- D.
BUTANE
Correct Answer
D. BUTANEExplanation
Butane is the correct answer because it is a flammable refrigerant that requires approval for use by the NYC Fire Department. R-22 and R-12 are both commonly used refrigerants but do not require special approval. Carbon dioxide is a non-flammable refrigerant and also does not require approval.Rate this question:
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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
- A.
TWO WAY VALVE
- B.
THREE WAY VALVE
- C.
PLUG VALVE
- D.
STOP VALVE
Correct Answer
B. THREE WAY VALVEExplanation
When installing a service valve to isolate a dual pressure device while keeping the system in service, a three-way valve would be used. A three-way valve has three ports, allowing for the diversion of flow between two different paths. In this case, the three-way valve would be able to redirect the flow from the dual pressure device to either the system or to a bypass line, effectively isolating the device without interrupting the system's operation.Rate this question:
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- 40.
THE SOLENOID UNLOADERS ON RECIPROCATING COMPRESSORS ARE DESIGNED TO UNLOAD:
- A.
ALL THE CYLINDERS
- B.
THE CLEARANCE SPACES IN THE CYLINDERS
- C.
CONTROL CAPACITY BY SHUTTING DOWN THE COMPRESSOR
- D.
CYLINDERS THAT CAN BE UNLOADED
Correct Answer
B. THE CLEARANCE SPACES IN THE CYLINDERSExplanation
The solenoid unloaders on reciprocating compressors are designed to unload the clearance spaces in the cylinders. When the compressor is unloaded, the solenoid unloaders open the clearance spaces to allow the compressed air to escape, reducing the pressure in the cylinders. This prevents the compressor from continuously compressing air and allows it to operate more efficiently. By unloading the clearance spaces, the compressor can control its capacity by adjusting the amount of air being compressed and prevent excessive pressure buildup.Rate this question:
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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:
- A.
RAISE THE CONDENSER LIQUID LEVEL TO THE MAXIMUM
- B.
PRODUCE A LARGE AMOUNT OF LIQUID SUB-COOLING
- C.
RAISE THE CONDENSER HEAD PRESSURE
- D.
LOWER THE CONDENSER PRESSURE
Correct Answer
D. LOWER THE CONDENSER PRESSUREExplanation
Lowering the condenser pressure results in a more efficient operation of a centrifugal compressor. When the condenser pressure is lowered, the temperature at which the refrigerant condenses decreases. This allows for a larger temperature difference between the condensing temperature and the evaporating temperature, which improves the overall efficiency of the refrigeration cycle.Rate this question:
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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?
- A.
AT HIGHER EVAPORATIVE TEMPERATURE AND LOW CONDENSER TEMPERATURE
- B.
LOW EVAPORATIVE TEMPERATURE AND HIGH CONDENSER TEMPERATURE
- C.
HIGHER EVAPORATIVE TEMPERATURE AND HIGH CONDENSER TEMPERATURE
- D.
LOW EVAPORATIVE TEMPERATURE AND LOW CONDENSER TEMPERATURE
Correct Answer
B. LOW EVAPORATIVE TEMPERATURE AND HIGH CONDENSER TEMPERATUREExplanation
The heat in BTU per minute absorbed by the condenser water in a refrigerating plant is greater under the condition of low evaporative temperature and high condenser temperature1. This is because the heat transfer in a refrigeration cycle is driven by the temperature difference between the refrigerant and the surrounding medium (in this case, the condenser water). A low evaporative temperature means the refrigerant absorbs less heat, and a high condenser temperature means it can reject more heat to the condenser water. Therefore, these conditions would result in the greatest heat absorption by the condenser water.Rate this question:
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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:
- A.
BALL
- B.
PLUG
- C.
GLOBE
- D.
GATE
Correct Answer
C. GLOBEExplanation
The operator should avoid using the globe valve because it typically has a higher pressure drop compared to the other options. Globe valves have a more complex design with a curved flow path, which causes more resistance to flow and results in a higher pressure drop. In contrast, ball, plug, and gate valves have a more streamlined flow path, allowing for lower pressure drop. Therefore, to minimize pressure drop, the operator should avoid using the globe valve.Rate this question:
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- 44.
IN AN EMERGENCY IF YOU MUST DUMP REFRIGERANT INTO SEWER, YOU WILL DUMP ONLY WHEN
- A.
SEWER IS NOT CONNECTED TO A STORM DRAIN
- B.
FIRST CONFIRM THAT REFRIGERANT IS NOT FLAMMABLE
- C.
FACILITY MANAGER APPROVES IT
- D.
YOU DISCHARGE UNDER THE SUPERVISION OF THE FIRE DEPT.
Correct Answer
D. YOU DISCHARGE UNDER THE SUPERVISION OF THE FIRE DEPT.Explanation
The correct answer is "YOU DISCHARGE UNDER THE SUPERVISION OF THE FIRE DEPT." because in an emergency situation where refrigerant needs to be dumped into the sewer, it is important to ensure that proper safety measures are followed. Discharging under the supervision of the fire department ensures that the process is carried out in a controlled manner, minimizing the risk of harm to the environment and individuals. The fire department can provide guidance and oversight to ensure that the disposal is done safely and in compliance with regulations.Rate this question:
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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:
- A.
CLOSE, THE COMPRESSOR PUMPS DOWN AND SHUTS DOWN ON LOW PRESSURE
- B.
CLOSE AND THE COMPRESSOR WILL START ON HIGH PRESSURE
- C.
OPEN AND COMPRESSOR WILL PUMP DOWN AND GO OFF ON HIGH PRESSURE
- D.
OPEN AND COMPRESSOR WILL CONTINUE TO RUN AT REDUCED SPEED
Correct Answer
A. CLOSE, THE COMPRESSOR PUMPS DOWN AND SHUTS DOWN ON LOW PRESSUREExplanation
The cold front caused a sharp drop in outside air temperature (O.A.T.), which would activate the thermostat. In response, the thermostat would cause the solenoid valve to close. As a result, the compressor would pump down and shut down due to 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 and reach low pressure, leading to a shutdown.Rate this question:
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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
- A.
THE FLOW OF OIL WILL NOT BE EFFECTED
- B.
YOU WILL HAVE INSUFFICIENT HEAD TO LIFT THE OIL
- C.
THE TEMPERATURE OF THE REFRIGERANT EXITING THE JETS WILL DECREASE
- D.
THE OIL IN THE BOTTOM OF THE CHILLER WILL NOT LIFT IF IT BECOMES MIXED WITH LESS REFRIGERANT
Correct Answer
B. YOU WILL HAVE INSUFFICIENT HEAD TO LIFT THE OILExplanation
If the flow of oil is restricted, it means that there is not enough pressure or force to lift the oil mixed with refrigerant. This results in insufficient head, which refers to the pressure difference needed to lift the oil. As a result, the oil will not be able to be lifted from the bottom of the evaporator.Rate this question:
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- 47.
LOW CONDENSING PRESSURE IS NOT GOOD BECAUSE
- A.
LIQUID LEVEL IN CONDENSER WILL FALL TOO LOW
- B.
COMPRESSOR WILL WORK HARDER
- C.
EXPANSION VALVES WILL NOT FEED PROPERLY
- D.
HEAD PRESSURE WILL INCREASE
Correct Answer
C. EXPANSION VALVES WILL NOT FEED PROPERLYExplanation
When the condensing pressure is low, it means that the pressure in the condenser is not sufficient to properly condense the refrigerant vapor into liquid form. This leads to a decrease in the liquid level in the condenser, causing the expansion valves to not be able to feed the refrigerant properly. As a result, the expansion valves will not be able to regulate the flow of refrigerant into the evaporator effectively, leading to inefficient cooling.Rate this question:
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- 48.
HEAT TRANSFER RATE IN THE CONDENSER WILL
- A.
INCREASE WITH THE VELOCITY OF THE WATER IN THE TUBES
- B.
SHOW ONLY A SMALL INCREASE IF TUBES ARE DESCALED
- C.
INCREASE WITH A LOWER LEAVING WATER TEMPERATURE DIFFERENCE
- D.
SHOW THE LEAST BENEFIT FOR DESCALING THE TUBES AT HIGH WATER VELOCITIES
Correct Answer
A. INCREASE WITH THE VELOCITY OF THE WATER IN THE TUBESExplanation
The heat transfer rate in the condenser will increase with the velocity of the water in the tubes because higher water velocity promotes better heat transfer. When the water flows faster through the tubes, it increases the turbulence and improves the heat transfer coefficient. This results in a higher heat transfer rate between the hot vapor and the cooling water, leading to increased efficiency in the condenser.Rate this question:
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- 49.
WHY SHOULD YOU CHARGE WITH VAPOR?
- A.
YOU COULD BREAK THE RUPTURE GUARD WITH LIQUID
- B.
YOU CAN ENTRAIN THE OIL IN THE REFRIGERANT WITH LIQUID
- C.
YOU CAN FREEZE WATER IN THE TUBES WITH LIQUID
- D.
YOU CAN OVER CHARGE THE SYSTEM WITH LIQUID
Correct Answer
C. YOU CAN FREEZE WATER IN THE TUBES WITH LIQUIDExplanation
Charging with liquid can cause water to freeze in the tubes, which can lead to blockages and damage to the system.Rate this question:
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- 50.
AN INLINE REFRIGERANT CLEANING SYSTEM IS ADVISABLE BECAUSE:
- A.
NON-CONDENSEABLES CANNOT BE PROPERLY PURGED
- B.
REFRIGERANT REACTS WITH THE LUBRICATION OIL
- C.
REFRIGERANT SYSTEM IS HIGH PRESSURE
- D.
REFRIGERANT IS A TOXIC CLASS
Correct Answer
B. REFRIGERANT REACTS WITH THE LUBRICATION OILExplanation
An inline refrigerant cleaning system is advisable because refrigerant reacts with the lubrication oil. This means that if the refrigerant is not properly cleaned, it can contaminate the lubrication oil, leading to decreased efficiency and potential damage to the system. By using an inline cleaning system, any contaminants or impurities in the refrigerant can be effectively removed before it comes into contact with the lubrication oil, ensuring the smooth operation and longevity of the refrigeration system.Rate this question:
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Apr 15, 2024Quiz Edited by
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Mar 01, 2019Quiz Created by
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