Refrigerant Machine Operator Certification Practice Test
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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. This test consists of 100 most important questions that will help you clear the certification exam of the same. All the best.
Questions and Answers
- 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 stream before it is discharged from the cooling tower. If these plates are clogged, they will not be able to effectively remove the water droplets, leading to a higher temperature in the water being returned to the cooling tower.Rate this question:
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- 2.
CONVERT 18" VACUUM TO PSIA
- A.
7.7
- B.
0.6
- C.
5.9
- D.
23.5
Correct Answer
C. 5.9 -
- 3.
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, it would cause the refrigerant in the suction line to be colder than normal. This can lead to the formation of frost in the suction line. Frost formation is an indication that the refrigerant is not in its ideal state and can cause a decrease in the compressor's efficiency. Therefore, the presence of frost in the suction line would be noticed by the RMO as a potential issue with the compressor receiving liquid instead of superheated vapor.Rate this question:
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- 4.
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 space being cooled, increasing the chances of leaks occurring. In contrast, indirect systems use a secondary fluid to cool the space, reducing the risk of refrigerant leaks. Indirect closed systems further minimize the risk by using a closed loop system, while indirect open systems have a higher chance of refrigerant leaks due to their open design.Rate this question:
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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.
- 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 to have the suction valve and discharge bypass both open. This is the proper procedure for starting the machine without unloaders. By having the suction valve open, it allows the machine to draw in the necessary fluid or gas. Opening the discharge bypass allows the fluid or gas to bypass the discharge valve, preventing any potential pressure buildup or damage to the machine. This ensures a safe and efficient start-up of the reciprocating machine.Rate this question:
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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:
- 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 heat transfer efficiency. As a result, the compressor would have to work harder to maintain the desired pressure, leading to an increase in head pressure.Rate this question:
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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
- 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 condition 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, causing the suction line and part of the compressor to frost over. This can result in reduced cooling capacity and potential damage to the compressor.Rate this question:
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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
- A.
80°F
- B.
90°F
- C.
110°F
- D.
130°F
Correct Answer
B. 90°FExplanation
Using warm water helps to increase the release rate of refrigerant from the drum when charging an R-12 reciprocating refrigeration system. However, the water temperature should not exceed 90°F. Temperatures higher than this could potentially cause the refrigerant to vaporize too quickly, leading to inefficient charging and potential damage to the system.Rate this question:
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- 9.
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 fire safety, the ANSI/ASHRAE refrigerant safety classification that is most dangerous is A3. This classification indicates that the refrigerant is highly flammable, posing a significant risk of fire. It is important to handle and store A3 refrigerants with extreme caution, following proper safety protocols to prevent accidents and ensure the safety of individuals and property.Rate this question:
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- 10.
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." At the condenser, the refrigerant enters as a high-pressure gas and undergoes a cooling process. This cooling causes the refrigerant to condense and transform into a high-pressure liquid. Therefore, the refrigerant leaves the condenser as a high-pressure liquid.Rate this question:
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- 11.
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
According to the NYC Fire Code classification of refrigerants, ammonia would fall under Group 2.Rate this question:
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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:
- 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
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, and reducing the resistance by 1/2 would result in a doubling of the current. Therefore, the power output of the motor would increase by a factor of 2.Rate this question:
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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?
- A.
WATER, OIL, REFRIGERANT
- B.
OIL, REFRIGERANT, WATER
- C.
REFRIGERANT, OIL, WATER
- D.
OIL, WATER, REFRIGERANT
Correct Answer
D. OIL, WATER, REFRIGERANTExplanation
In this scenario, the water, moisture, and fluids would settle in the container from top to bottom in the order of oil, water, and refrigerant. This is because oil is denser than water and refrigerant, so it would settle at the bottom. Water, being less dense than oil but denser than refrigerant, would settle above the oil layer. Refrigerant, being the least dense, would settle at the top. Therefore, the correct order is oil, water, and refrigerant.Rate this question:
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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
- 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 r is the radius of the cylinder and h is the height or stroke. In this case, the radius is half of the bore, so it would be 6 inches. The stroke is given as 16 inches. Plugging these values into the formula, we get V = π(6^2)(16) = 1808 cubic inches. Therefore, the volume of refrigerant in the cylinder would be closer to 1808 cubic inches.Rate this question:
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- 15.
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
A. 32Explanation
To convert from Celsius (°C) to Fahrenheit (°F), you can use the formula:°F = (°C × 9/5) + 32Given that the temperature has dropped 10°C, we can calculate the new temperature in °F:°F = (°C - 10) × 9/5 + 32Substituting the value of -10°C into the formula:°F = (-10 × 9/5) + 32°F = (-18) + 32°F = 14Therefore, the temperature in °F is 14.Rate this question:
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- 16.
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 because these systems are more prone to leaks and contaminants entering the system. Operating below atmospheric pressure can cause air and moisture to enter the system, which can lead to reduced efficiency and potential damage to the system. Therefore, an automatic purge unit is necessary to remove any non-condensable gases and maintain the proper pressure and purity of the refrigerant in the system.Rate this question:
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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
- 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. In addition to this, the vessel in which they are contained can also serve as an economizer. An economizer is a device that helps in improving the efficiency of a system by utilizing waste heat or energy. In this case, the vessel containing the orifice plates can be designed in such a way that it recycles and utilizes the waste heat or energy generated by the system, thereby serving as an economizer.Rate this question:
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- 18.
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
The rupture disc in a centrifugal refrigerating machine is normally located on the evaporator. The evaporator is responsible for absorbing heat from the surroundings and evaporating the refrigerant, thus cooling the system. Placing the rupture disc on the evaporator ensures that any excessive pressure buildup in the system is released at the point where the refrigerant is being evaporated. This helps to prevent any potential damage or failure of the evaporator due to high pressure, ensuring the safe operation of the refrigerating machine.Rate this question:
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- 19.
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 it. When a pump is operated, it creates a pressure difference that forces the fluid or gas to move from an area of lower pressure to an area of higher pressure. This increase in pressure allows the fluid or gas to be transported or used for various purposes, such as in water supply systems, hydraulic systems, or air compression systems. Therefore, the correct answer is "RAISING PRESSURE."Rate this question:
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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.
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 discharge valve, the operator is restricting the flow of water from the pump, thereby reducing the overall flow rate to the condenser.Rate this question:
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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
- 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). As an RMO in charge, it is requested to replace the gauge on the high side of the refrigeration system. The pressure graduation rate should be at least 1.2 times the design pressure. This ensures that the gauge can accurately measure and withstand the pressure of the system. Additionally, the rupture guard also needs to be replaced, indicating the importance of safety measures. Lastly, the gauge should be a compound gauge, which means it can measure both positive and negative pressures.Rate this question:
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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
- 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
When a refrigeration unit is short cycling and using a low side float valve, it means that there is not enough refrigerant in the system. This can cause the compressor to turn on and off frequently, leading to inefficient operation and potential damage to the equipment. Therefore, the correct action in this situation would be to charge additional refrigerant into the system. This will ensure that the unit has enough refrigerant to operate properly and prevent short cycling.Rate this question:
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- 23.
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 created by joining two pieces of metal with a filler metal that has a lower melting point than the base metals. The filler metal is heated to its melting point and then flows into the joint, creating a strong bond. A brazed joint is known for its ability to create a gas tight fitting, meaning it forms a seal that prevents the escape or entry of gases. This is why "gas tight fitting" is the most correct way to describe a brazed joint.Rate this question:
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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:
- 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
Lowering the compressor suction operating pressure will decrease the temperature of the water supply. When the suction pressure is lowered, the refrigerant entering the compressor will have a lower temperature, resulting in a lower discharge temperature. This will lead to a colder water supply being produced.Rate this question:
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- 25.
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 absorbed or released during a phase change, such as during evaporation or condensation. A low latent heat means that the refrigerant is not able to absorb or release a significant amount of heat during these phase changes, which can result in inefficient cooling or heating processes. Therefore, a refrigerant with a low latent heat would not be effective in maintaining the desired temperature in a refrigeration system.Rate this question:
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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
- 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 restrict the flow of refrigerant, leading to a decrease in the amount of refrigerant entering the evaporator coil. This results in a higher superheat temperature, as the refrigerant is not able to absorb enough heat from the surrounding air before entering the compressor.Rate this question:
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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
- 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 provided, the cycling times of the refrigerating unit are normal, indicating that the machine control is functioning properly. The only readings that are outside the normal rate are compressor compression and temperature. This suggests that there may be an issue with the compressor valves, as faulty valves can affect the compression and temperature of the unit. Therefore, inspecting for faulty compressor valves would be the appropriate service requirement in this situation.Rate this question:
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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:
- 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 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 means that when making repairs, the flame should be contained within a safe enclosure and any fumes or gases produced should be directed outside to prevent any potential hazards. This is necessary to prevent the risk of fire or explosion due to the presence of the flammable refrigerant in the facility.Rate this question:
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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:
- A.
SOLENOID VALVE
- B.
HIGH SIDE FLOAT
- C.
THERMAL EXPANSION VALVE
- D.
CAPILLARY TUBE
Correct Answer
A. SOLENOID VALVEExplanation
A solenoid valve is a device that controls the flow of fluid by using an electromagnetic solenoid. In this case, the question states that the RMO needed to vary the flow of refrigerant in a system. The other three options, high side float, thermal expansion valve, and capillary tube, are all components commonly used in refrigeration systems to regulate and control the flow of refrigerant. Therefore, the solenoid valve is the odd one out as it is not specifically mentioned in relation to varying the flow of refrigerant.Rate this question:
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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:
- 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 most likely way to achieve capacity control in a reciprocating compressor is by opening the suction valves with some form of control. By controlling the opening of the suction valves, the amount of gas entering the compressor can be regulated, thus controlling the capacity of the compressor. This allows for precise control and adjustment of the compressor's output based on the demand or process requirements.Rate this question:
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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:
- 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 that the air surrounding the cooling tower has become drier. This decrease in humidity means that the cooling tower is able to evaporate more water, resulting in a lower cooling water 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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- 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:
- 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 a safety device used in refrigerating systems to prevent overpressure. It is designed to open and release excess pressure when the pressure in the system exceeds a certain threshold, known as the design pressure. Therefore, a RMO (Refrigeration Maintenance Operator) would expect a relief valve to start functioning at the design pressure, as this is the pressure at which it is designed to activate and protect the system. The other options, such as 5% over design pressure or 20% below design pressure, are not accurate because the relief valve should only open when the pressure reaches the design pressure.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 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 distribution and avoid overcharging the system. Charging on the high pressure side can lead to overpressurization and potential damage to the equipment. The discharge side and receiver are not typically used for charging refrigerant.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 air or gas that needed to be removed from the system has been successfully purged. Continuing to purge after the pressure has stopped dropping would be unnecessary and potentially wasteful.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 heat that is removed from the building is finally rejected as heat of evaporation of the cooling tower. This means that the cooling tower uses the process of evaporation to remove heat from the building. As the water in the cooling tower evaporates, it absorbs heat from the building, thereby cooling the building. This heat is then released into the atmosphere as the water vaporizes, thus rejecting the heat 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 because it is a type of hydrochlorofluorocarbon (HCFC) refrigerant that has been phased out due to its harmful effects on the ozone layer. It has been replaced by more environmentally friendly refrigerants such as R-410A. Calcium chloride, glycol, and sodium chloride are commonly used as cooling mediums in indirect systems.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". In a refrigeration plant, the true power consumption can be determined by multiplying the voltage (V) by the current (A) and the power factor. The power factor represents the efficiency of the motor in converting electrical power to mechanical power. Multiplying all three values together gives the power consumption in watts.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 refrigerant that requires approval for use by the NYC Fire Department. This is because butane is highly flammable and poses a fire hazard. The NYC Fire Department regulates the use of certain refrigerants to ensure safety and prevent accidents or fires. R-22 and R-12 are commonly used refrigerants, but they do not require approval from the fire department. Carbon dioxide is a natural refrigerant and is considered safe for use.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 valve can be used to redirect the flow from the dual pressure device to either the system or to a bypass line, effectively isolating the device while still maintaining the flow in the system.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. The clearance space refers to the area between the piston and the cylinder head when the piston is at the top dead center. By unloading the clearance spaces, the compressor can reduce the compression ratio and decrease the workload on the compressor. This helps to improve efficiency and reduce wear and tear on the compressor components.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. The condenser pressure is directly related to the head pressure, which is the pressure at the outlet of the condenser. By lowering the condenser pressure, the compressor has less work to do in order to maintain the desired pressure levels, leading to improved efficiency. This allows the compressor to use less energy and operate more efficiently.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
D. LOW EVAPORATIVE TEMPERATURE AND LOW CONDENSER TEMPERATUREExplanation
The correct answer is "LOW EVAPORATIVE TEMPERATURE AND LOW CONDENSER TEMPERATURE". In a refrigerating plant, the condenser water absorbs heat from the refrigerant to cool it down and condense it back into a liquid. The amount of heat absorbed by the condenser water is greater when both the evaporative temperature (temperature at which the refrigerant evaporates) and the condenser temperature are low. This is because a lower evaporative temperature means that more heat needs to be removed from the refrigerant, and a lower condenser temperature allows for more efficient heat transfer from the refrigerant to 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 valve types. Globe valves have a more complex design with a restrictive flow path, which causes the pressure to drop significantly as the fluid passes through. In contrast, ball, plug, and gate valves have a more streamlined flow path, resulting in 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
When faced with an emergency situation where refrigerant must be dumped into the sewer, the only appropriate action is to discharge the refrigerant under the supervision of the fire department. This ensures that the process is carried out safely and in compliance with regulations. The fire department will have the necessary expertise and resources to handle the situation and minimize any potential risks or harm to the environment.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
A cold front causes a sharp drop in Outside Air Temperature (O.A.T.). In this condition, the thermostat will cause the solenoid valve to close. When the solenoid valve closes, it will prevent the flow of refrigerant into the compressor. As a result, the compressor will pump down, meaning it will remove the refrigerant from the system until the pressure reaches a low level. Once the pressure drops to a certain point, the compressor will shut down to prevent damage. Therefore, the correct answer is "CLOSE, THE COMPRESSOR PUMPS DOWN AND SHUTS DOWN ON LOW PRESSURE."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, there will not be enough pressure or force to lift the oil using the jet ejector. The term "head" refers to the pressure or force exerted by the fluid, and if it is insufficient, the oil will not be able to be lifted. Therefore, the correct answer is "you will have insufficient head to lift the oil."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 below the normal operating range. This can cause the liquid level in the condenser to fall too low, leading to inadequate cooling and potential damage to the compressor. Additionally, when the condensing pressure is low, the expansion valves may not be able to feed the proper amount of refrigerant into the evaporator, leading to inefficient cooling and reduced system performance. Therefore, low condensing pressure is not good because it can cause the expansion valves to not feed properly.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 correct answer is "INCREASE WITH THE VELOCITY OF THE WATER IN THE TUBES." This is because as the velocity of the water in the tubes increases, it promotes better heat transfer between the water and the condenser tubes. This increased velocity helps to remove heat more efficiently, resulting in a higher heat transfer rate 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 in the tubes to freeze. When liquid refrigerant is introduced into the system, it can cause a rapid drop in temperature, leading to the formation of ice. This ice can block the flow of refrigerant and restrict the system's efficiency. Charging with vapor, on the other hand, allows for a gradual increase in temperature, preventing the formation of ice and ensuring proper functioning of 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 over time, the refrigerant can degrade the quality of the lubrication oil, leading to reduced performance and potential damage to the refrigeration system. By using an inline cleaning system, any contaminants or impurities in the refrigerant can be removed, preventing them from reacting with the lubrication oil and ensuring the system operates at its optimal level.Rate this question:
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Current Version
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Mar 17, 2024Quiz Edited by
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Feb 08, 2014Quiz Created by
Catherine Halcomb