Refrigerant Machine Operator Trivia Test #2
PRACTICE EXAM #2
- 1.
OF THE FOLLOWING CHARACTERISTICS OF REFRIGERANT, THE ONE THAT BEST DESCRIBES REFRIGERANT 22 IS:
- A.
ODORLESS WHEN MIXED WITH AIR
- B.
AN ETHER LIKE ODOR WHEN MIXED WITH AIR
- C.
EXPLOSIVE WHEN MIXED WITH AIR
- D.
BOILS AT HIGHER TEMP THAT R-12
Correct Answer
A. ODORLESS WHEN MIXED WITH AIRExplanation
Refrigerant 22 is best described as odorless when mixed with air. This means that when Refrigerant 22 is released into the air and mixed with it, it does not produce any distinct smell. This characteristic is important for safety reasons, as an odorless refrigerant can be difficult to detect in case of a leak or release. It is crucial to be aware of the characteristics of refrigerants to ensure proper handling and maintenance of refrigeration systems.Rate this question:
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- 2.
BECAUSE OF THE LATENT HEAT LOAD, REFRIGERATION MACHINE OPERATOR WAS INSTRUCTED TO START THE RECIPROCATING PLANT FOR AIR CONDITIONING. OF THE FOLLOWING ACCORDING TO RECOMMENDED PRACTICE, THE FIRST THING TO DO IS
- A.
TURN ON CHILLED WATER PUMPS AND OPEN THE BYPASS TO LIGHTER LOAD
- B.
INSTALL LARGER FUSE TO TAKE THE INITIAL LOAD, AND THEN TURN ON THE COOLING TOWER FANS
- C.
TURN ON CHILLED WATER PUMP, CONDENSER WATER PUMPS AND COOLING TOWER FANS
- D.
SET THE THERMOSTAT A FEW DEGREES HIGHER
Correct Answer
C. TURN ON CHILLED WATER PUMP, CONDENSER WATER PUMPS AND COOLING TOWER FANSExplanation
The correct answer is to turn on the chilled water pump, condenser water pumps, and cooling tower fans. This is because the latent heat load requires the cooling system to be activated in order to remove the heat from the air conditioning system. By turning on the chilled water pump, condenser water pumps, and cooling tower fans, the necessary cooling capacity will be provided to meet the increased heat load.Rate this question:
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- 3.
THE MOST IMPORTANT REASON TO USE 2 COMPRESSORS IN A CASCADE SYSTEM IS TO:
- A.
ACCOMPLISH LOWER TEMPERATURE
- B.
PERMIT THE USE OF INEXPENSIVE LUBRICATING OIL
- C.
AVOID THE NEED FOR VERY HIGH COMPRESSION RATIOS
- D.
DIVIDE THE COOLING LOAD BETWEEN 2 COMPRESSORS
Correct Answer
A. ACCOMPLISH LOWER TEMPERATUREExplanation
Using two compressors in a cascade system allows for accomplishing lower temperatures. This is because each compressor can operate at a different pressure level, which enables the system to achieve lower temperatures than what could be achieved with a single compressor. By dividing the cooling load between the two compressors, the system can effectively lower the temperature and provide efficient cooling.Rate this question:
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- 4.
THE ADVANTAGE OF FORCED DRAFT OVER NATURAL DRAFT COOLING TOWER IS:
- A.
THE POSSIBILITY OF LOWER WATER OUT TEMP
- B.
THERE IS NO DEPENDENCE ON NATURAL WIND VELOCITY
- C.
USE OF A SMALLER TOWER SIZE
- D.
ALL OF THE ABOVE
Correct Answer
D. ALL OF THE ABOVEExplanation
Forced draft cooling towers have the advantage of lower water outlet temperature compared to natural draft cooling towers. This is because forced draft cooling towers use fans to force air through the tower, resulting in better heat transfer and lower water temperatures. Additionally, forced draft cooling towers do not rely on natural wind velocity, allowing for consistent cooling performance regardless of environmental conditions. Lastly, forced draft cooling towers can be designed to be smaller in size compared to natural draft cooling towers, making them more space-efficient. Therefore, all of the given options are advantages of forced draft over natural draft cooling towers.Rate this question:
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- 5.
WHAT IS 29.92" HG IN KPA
- A.
101.3
- B.
101.28
- C.
101.26
- D.
103.2
Correct Answer
A. 101.3Explanation
The correct answer is 101.3. This is because 29.92" HG is a unit of pressure commonly used in aviation and meteorology to measure atmospheric pressure. It is equivalent to 101.3 kilopascals (kPa), which is the standard atmospheric pressure at sea level.Rate this question:
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- 6.
THE MECHANISM SITTING ABOVE THE EVAPORATOR IS KNOWN AS
- A.
ECONOMIZER
- B.
PURGE UNIT
- C.
AIR BLEED
- D.
PRESSURE RELIEF VALVE
Correct Answer
B. PURGE UNITExplanation
The mechanism sitting above the evaporator is known as the purge unit.Rate this question:
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- 7.
THE RUPTURE DISK IS ALWAYS PIPED INTO THE
- A.
HIGH SIDE
- B.
LOW SIDE
- C.
EITHER SIDE OF SYSTEM
- D.
NEITHER SIDE SYSTEM
Correct Answer
B. LOW SIDEExplanation
The rupture disk is always piped into the low side of the system. This is because the low side of the system typically operates at a lower pressure than the high side. Placing the rupture disk in the low side ensures that it will rupture and relieve pressure when the pressure in the system exceeds a certain limit, preventing damage to the system.Rate this question:
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- 8.
CONCERNING LEAKAGE, WHICH STATEMENT IS MOST CORRECT?
- A.
GATE VALVE CAUSES LESS LEAKAGE
- B.
GLOBE VALVES CAUSES MORE LEAKAGE
- C.
ALL VALVES ARE THE SAME
- D.
GATE VALVES CAUSES MORE LEAKAGE
Correct Answer
D. GATE VALVES CAUSES MORE LEAKAGEExplanation
Gate valves cause more leakage. This is because gate valves have a sliding gate that moves up and down to control the flow of fluid. When the valve is closed, there is a small gap between the gate and the valve body, which can result in some leakage. Globe valves, on the other hand, have a plug that moves perpendicular to the flow of fluid, creating a tighter seal when closed and reducing the chances of leakage. Therefore, gate valves are more prone to leakage compared to globe valves.Rate this question:
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- 9.
WHAT SHAFT SEAL PREVENTS VAPOR FROM LEAKING OUT OF COMPRESSOR?
- A.
STUFFING BOX
- B.
ELECTRO-MECHANICAL SEAL
- C.
MECHANICAL SEAL
- D.
ALL OF THE ABOVE
Correct Answer
A. STUFFING BOXExplanation
A stuffing box is a type of shaft seal that prevents vapor from leaking out of a compressor. It is a traditional type of seal that uses packing material, such as braided rope or graphite, to create a tight seal around the shaft. This packing material is compressed against the shaft, preventing any vapor from escaping. Therefore, the correct answer is "STUFFING BOX."Rate this question:
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- 10.
A FUSIBLE PLUG MELTS AT
- A.
450°F
- B.
280°F
- C.
212°F
- D.
800°F
Correct Answer
B. 280°FExplanation
A fusible plug is designed to melt at a specific temperature in order to release pressure or prevent an explosion in a system. In this case, the correct answer is 280°F. When the temperature reaches this point, the fusible plug will melt, allowing any excess pressure to be released. This helps to prevent damage to the system or potential harm to individuals.Rate this question:
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- 11.
WHEN WILL THE BTUs ABSORBED BY THE CONDENSING WATER BE THE GREATEST?
- A.
LOW CONDENSER TEMPERATURE, LOW CONDENSER WATER TEMPERATURE
- B.
HIGH CONDENSER TEMPERATURE, HIGH CONDENSER WATER TEMPERATURE
- C.
HIGH CONDENSER TEMPERATURE, LOW CONDENSER WATER TEMPERATURE
- D.
LOW CONDENSER TEMPERATURE, HIGH CONDENSER WATER TEMPERATURE
Correct Answer
C. HIGH CONDENSER TEMPERATURE, LOW CONDENSER WATER TEMPERATUREExplanation
The BTUs absorbed by the condensing water will be the greatest when the condenser temperature is high and the condenser water temperature is low. This is because a high condenser temperature means that the refrigerant is transferring more heat to the condensing water, while a low condenser water temperature allows the water to absorb more heat from the refrigerant. Therefore, the combination of high condenser temperature and low condenser water temperature maximizes the heat transfer and results in the greatest amount of BTUs absorbed by the condensing water.Rate this question:
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- 12.
FLOODED EVAPORATORS HAVE HIGH HEAT TRANSFER PER SQUARE FOOT, WHAT MAY BE A DISADVANTAGE?
- A.
REQUIRES A SMALLER CHARGE
- B.
REQUIRES A HIGHER CHARGE
- C.
REQUIRES A USE OF A TXV FOR PROPER FEED
- D.
WATER HAS TO BE DRAINED DAILY
Correct Answer
B. REQUIRES A HIGHER CHARGEExplanation
A flooded evaporator requires a higher charge of refrigerant compared to other types of evaporators. This can be seen as a disadvantage because a higher charge means more refrigerant is needed, which can increase the cost of the system and also pose potential safety risks. Additionally, a higher charge can also lead to increased energy consumption and environmental impact.Rate this question:
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- 13.
SHELL AND TUBE CONDENSERS HAVE THE ADVANTAGE OF:
- A.
REMOVING HEADS FOR CLEANING THE WATER SIDES OF THE TUBES
- B.
THE REFRIGERANT CONNECTIONS DOES NOT HAVE TO BE DISRUPTED
- C.
USING ACID FOR CLEANING
- D.
BOTH A AND B ARE CORRECT
Correct Answer
D. BOTH A AND B ARE CORRECTExplanation
Shell and tube condensers have the advantage of both being able to remove heads for cleaning the water sides of the tubes and not having to disrupt the refrigerant connections. This means that maintenance and cleaning of the condenser can be done more easily and efficiently without the need to disconnect the refrigerant connections.Rate this question:
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- 14.
SHELL AND COIL CONDENSERS HAVE THE ADVANTAGE OF:
- A.
REMOVING HEADS FOR CLEANING THE WATER SIDES OF THE TUBES
- B.
THE REFRIGERANT CONNECTIONS DO NOT HAVE TO BE DISRUPTED
- C.
HAS LESS CHANCE OF DEVELOPING LEAKS
- D.
BOTH A AND B ARE CORRECT
Correct Answer
C. HAS LESS CHANCE OF DEVELOPING LEAKSExplanation
Shell and coil condensers have the advantage of having less chance of developing leaks. This means that compared to other types of condensers, shell and coil condensers are less likely to experience leaks, which can be beneficial in terms of maintenance and overall efficiency.Rate this question:
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- 15.
HOW MANY BTUs WOULD BE REMOVED IN A 30 TON SYSTEM?
- A.
12,000 PER HOUR
- B.
360,000 PER MINUTE
- C.
12,000 PER MINUTE
- D.
360,000 PER HOUR
Correct Answer
D. 360,000 PER HOURExplanation
A 30-ton system would remove 12,000 BTUs per minute. Since there are 60 minutes in an hour, the total amount of BTUs removed in an hour would be 12,000 BTUs/minute * 60 minutes/hour = 720,000 BTUs/hour. However, the correct answer is 360,000 BTUs per hour, which is half of the calculated amount.Rate this question:
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- 16.
IF YOU HAVE 62 PSI AT 35°F AND 70 PSI AT 45°F, WHAT WOULD 38°F BE?
- A.
66
- B.
64.4
- C.
65
- D.
62
Correct Answer
B. 64.4Explanation
The given question is about the relationship between temperature and pressure. As the temperature decreases, the pressure also decreases. Therefore, if the pressure at 35°F is 62 PSI and the pressure at 45°F is 70 PSI, it can be inferred that the pressure at 38°F would be between 62 PSI and 70 PSI. The closest option to this range is 64.4 PSI, which is the correct answer.Rate this question:
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- 17.
COPPER USED IN REFRIGERATION SYSTEMS, LIKE IN HEAT EXCHANGERS, BECAUSE?
- A.
EASY FABRICATION
- B.
EASY DURABILITY
- C.
HIGH THERMAL CONDUCTIVITY
- D.
FLEXIBILITY
Correct Answer
C. HIGH THERMAL CONDUCTIVITYExplanation
Copper is used in refrigeration systems, like in heat exchangers, because of its high thermal conductivity. Thermal conductivity refers to the ability of a material to conduct heat. Copper has one of the highest thermal conductivity values among commonly used metals, making it an ideal choice for transferring heat efficiently in refrigeration systems. This allows for effective cooling and temperature regulation, ensuring the proper functioning of the refrigeration system.Rate this question:
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- 18.
THE ACCESSORIES ON THE LIQUID LINE ARE IN WHAT ORDER?
- A.
SOLENOID VALVE, DRIER, AND SIGHT-GLASS
- B.
RECEIVER, DRIER, SOLENOID VALVE, AND SIGHT-GLASS
- C.
MUFFLER, DRIER, SIGHT-GLASS AND SOLENOID VALVE
- D.
ACCUMULATOR, MUFFLER, DRIER, SIGHT-GLASS
Correct Answer
B. RECEIVER, DRIER, SOLENOID VALVE, AND SIGHT-GLASSExplanation
The correct answer is "RECEIVER, DRIER, SOLENOID VALVE, AND SIGHT-GLASS". This order is the most common arrangement for the accessories on the liquid line in a refrigeration system. The receiver is typically placed first to store and hold the liquid refrigerant, followed by the drier to remove any moisture or contaminants. The solenoid valve is then installed to control the flow of refrigerant, and finally, the sight-glass is added to visually inspect the refrigerant's condition and flow.Rate this question:
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- 19.
A CONDENSER IS 20' LONG AND 6' IN DIAMETER, WHAT IS THE VOLUME IN GALLONS IF 7.48 GALLONS IS 1 CU/FT?
- A.
565
- B.
4227
- C.
1808
- D.
1205
Correct Answer
B. 4227Explanation
The volume of a cylinder can be calculated using the formula V = πr^2h, where r is the radius and h is the height. In this case, the radius is half of the diameter, so it is 6/2 = 3 feet. The height is given as 20 feet. Plugging these values into the formula, we get V = π(3^2)(20) = 180π cubic feet. Since 7.48 gallons is equal to 1 cubic foot, we can convert the volume to gallons by multiplying by 7.48. Therefore, the volume in gallons is 180π * 7.48 ≈ 4241.71. The closest answer choice to this value is 4227.Rate this question:
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- 20.
WHAT IS THIS USED FOR?
- A.
RECYCLING
- B.
RECOVERY
- C.
RECLAIMING
- D.
PURGING
Correct Answer
B. RECOVERYExplanation
Recovery is the process of retrieving or extracting valuable materials or substances from waste or discarded products. It involves collecting and reusing materials that would otherwise be disposed of, reducing waste and conserving resources. This can include recovering materials such as metals, plastics, paper, and glass through methods like sorting, shredding, and melting. Recovery plays a crucial role in sustainable waste management and helps to minimize the environmental impact of waste disposal.Rate this question:
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- 21.
IF THE LOW PRESSURE CUTOUT CYCLES THE COMPRESSOR OFF, WHAT STARTS THE COMPRESSOR AGAIN?
- A.
SOLENOID VALVE
- B.
HIGH PRESSURE CUT OUT
- C.
LOW PRESSURE CUT OUT
- D.
THERMOSTAT
Correct Answer
C. LOW PRESSURE CUT OUTExplanation
When the low pressure cutout cycles the compressor off, it means that the pressure in the system has dropped below a certain threshold. In order to start the compressor again, the low pressure cutout will need to sense that the pressure has increased back to an acceptable level. This is why the correct answer is "LOW PRESSURE CUT OUT" - it is responsible for monitoring and controlling the pressure in the system, ensuring that the compressor only restarts when it is safe to do so.Rate this question:
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- 22.
REMOVING THE INSULATION ON THE SUCTION LINE, WITH THE ENGINE TEMPERATURE AT 85°F, WHAT WILL OCCUR?
- A.
FLOODED EVAPORATOR
- B.
STARVED EVAPORATOR
- C.
EXCESSIVE SUPERHEAT
- D.
LOW SUPERHEAT
Correct Answer
C. EXCESSIVE SUPERHEATExplanation
Removing the insulation on the suction line with the engine temperature at 85°F will result in excessive superheat. Superheat refers to the temperature of the refrigerant vapor above its boiling point. In this scenario, removing the insulation will cause the suction line to absorb more heat from the surrounding environment, resulting in higher temperatures and excessive superheat. This can lead to decreased cooling efficiency and potential damage to the system.Rate this question:
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- 23.
IF YOU WERE RUNNING THREE COMPRESSORS, WHICH BEST DESCRIBES THE STATE OF REFRIGERANT LEAVING THE THIRD EVAPORATOR COIL?
- A.
MOSTLY LIQUID, SOME VAPOR
- B.
MOSTLY VAPOR, SOME LIQUID
- C.
SUPERHEATED VAPOR
- D.
HIGHLY SUPERHEATED VAPOR
Correct Answer
C. SUPERHEATED VAPORExplanation
When running three compressors, the refrigerant leaving the third evaporator coil would be in the state of superheated vapor. This means that the refrigerant has absorbed enough heat to completely vaporize, and then some additional heat has been added to raise its temperature above the saturation point. As a result, the refrigerant leaving the coil is in a gaseous state and is hotter than the saturation temperature for that particular pressure.Rate this question:
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- 24.
WHAT TYPE OF PUMP IS THIS?
- A.
CENTRIFUGAL CHILLED WATER PUMP
- B.
RECIPROCATING CONDENSER WATER PUMP
- C.
RECIPROCATING CHILLED WATER PUMP
- D.
CENTRIFUGAL CONDENSER WATER PUMP
Correct Answer
A. CENTRIFUGAL CHILLED WATER PUMPExplanation
This pump is a centrifugal chilled water pump.Rate this question:
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- 25.
AN ELECTRIC MOTOR THAT IS RATED AT 3 HP WILL?
- A.
USE THREE PHASE
- B.
NEED A CAPACITOR
- C.
USE SINGLE PHASE
- D.
WILL RUN WITH REDUCED POWER OUTPUT
Correct Answer
A. USE THREE pHASEExplanation
An electric motor that is rated at 3 HP will use three-phase power. Three-phase power is commonly used for high-power applications and is more efficient and reliable compared to single-phase power. It provides a constant and balanced power supply, allowing the motor to run smoothly and efficiently. Therefore, a motor rated at 3 HP will require three-phase power to operate effectively.Rate this question:
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- 26.
IN A 3 STAGE CENTRIFUGAL CHILLER, WHAT HAPPENS TO THE PRESSURE AS IT REACHES THE FINAL STAGE?
- A.
INCREASES
- B.
DECREASES
- C.
SPEED CHANGES NOT PRESSURE
- D.
VOLUME CHANGES NOT PRESSURE
Correct Answer
A. INCREASESExplanation
In a 3 stage centrifugal chiller, the pressure increases as it reaches the final stage. This is because each stage of the chiller adds more pressure to the refrigerant as it passes through. As the refrigerant moves from stage to stage, it goes through a series of impellers that compress the refrigerant and increase its pressure. Therefore, by the time it reaches the final stage, the pressure is higher compared to the initial stage.Rate this question:
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- 27.
WITH AN INDUCED DRAFT COOLING TOWER, WHAT IS THE LOWEST TEMPERATURE ATTAINABLE FOR A COOLING TOWER?
- A.
WET BULB EQUAL TO DRY BULB
- B.
DRY BULB SLIGHTLY LOWER THAN WET BULB
- C.
DRY BULB HIGHER THAN WET BULB
- D.
WET BULB CAN NEVER BE LOWER THAN DRY BULB
Correct Answer
C. DRY BULB HIGHER THAN WET BULBExplanation
In an induced draft cooling tower, the lowest temperature attainable is when the dry bulb temperature is higher than the wet bulb temperature. The wet bulb temperature represents the lowest temperature that can be achieved through evaporative cooling. When the dry bulb temperature is higher than the wet bulb temperature, it means that the cooling tower is not able to cool the water to a lower temperature than the surrounding air. Therefore, the dry bulb temperature must be higher than the wet bulb temperature for an induced draft cooling tower.Rate this question:
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- 28.
WHEN A COMPRESSOR IS RUNNING FINE AT FULL FLOW AND YOU THROTTLE DOWN FLOW CAUSING THE COMPRESSOR TO STOP RUNNING NORMAL (SHORT CYCLE), WHY WOULD THIS HAPPEN?
- A.
DIRTY FILTER/STRAINER
- B.
AIR GETTING IN SEALS
- C.
LOW PRESSURE CUT OUT
- D.
HIGH HEAD PRESSURE
Correct Answer
C. LOW PRESSURE CUT OUTExplanation
When a compressor is running fine at full flow and you throttle down the flow causing the compressor to stop running normally (short cycle), this could happen due to a low pressure cut out. The low pressure cut out is a safety feature in the compressor that shuts off the compressor when the pressure drops below a certain threshold. Throttling down the flow reduces the pressure, causing the cut out to activate and stop the compressor from running normally.Rate this question:
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- 29.
WHEN DRY BULB IS 75°F AND WET BULB IS 75°F:
- A.
NOT POSSIBLE
- B.
VERY LOW HUMIDITY
- C.
THERMOMETER IS DEFECTIVE
- D.
100% RELATIVE HUMIDITY
Correct Answer
D. 100% RELATIVE HUMIDITYExplanation
When the dry bulb temperature and wet bulb temperature are both 75°F, it indicates that the air is saturated with moisture and cannot hold any more water vapor. This means that the relative humidity is at its maximum level of 100%.Rate this question:
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- 30.
WHEN A COMPRESSOR IS SAID TO HAVE A SAFETY HEAD THIS MEANS
- A.
COMPRESSOR OPERATES WITH NORMAL PRESSURES
- B.
COMPRESSOR OPERATES WITH LOW PRESSURES
- C.
COMPRESSOR HAS PRESSURE RELIEF VALVE
- D.
COMPRESSOR HAS HIGH PRESSURE CUT OUT
Correct Answer
C. COMPRESSOR HAS PRESSURE RELIEF VALVEExplanation
When a compressor is said to have a safety head, it means that the compressor is equipped with a pressure relief valve. This valve is designed to open and release excess pressure from the compressor system, ensuring that the pressure does not exceed safe limits. This helps to prevent any potential damage or failure of the compressor due to excessive pressure buildup.Rate this question:
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- 31.
THE CYLINDER UNLOADER CONTROLS CAPACITY, IS THERE ANY OTHER FUNCTION IT MAY HAVE?
- A.
ASSIST WITH COMPRESSOR SHUT DOWN
- B.
ASSIST WITH COMPRESSOR START UP
- C.
THERE IS NO OTHER FUNCTION
- D.
RELEASES PRESSURE
Correct Answer
B. ASSIST WITH COMPRESSOR START UPExplanation
The cylinder unloader not only controls the capacity of the compressor but also assists with the compressor start up. This means that it helps in the initial activation of the compressor, ensuring that it starts smoothly and efficiently.Rate this question:
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- 32.
AN OPERATOR SUSPECTS THAT SHORTED MOTOR WINDINGS HAVE CAUSED THE MOTOR OVERLOADS TO TRIP. IN ORDER TO INVESTIGATE THIS CONDITION, THE OPERATOR WOULD BE MOST CORRECT TO USE
- A.
CAPACITOR
- B.
VOLTMETER
- C.
OHMMETER
- D.
AMMETER
Correct Answer
C. OHMMETERExplanation
The operator suspects that shorted motor windings have caused the motor overloads to trip. To investigate this condition, the operator would be most correct to use an ohmmeter. An ohmmeter is used to measure the resistance in a circuit, and by measuring the resistance of the motor windings, the operator can determine if there is a short circuit present. If the ohmmeter shows a low resistance reading, it indicates a shorted winding. Therefore, using an ohmmeter would be the most appropriate tool for the operator to investigate the suspected condition.Rate this question:
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- 33.
WHEN RECOVERING R-22, WHAT COLOR WOULD THE CYLINDER BE THAT YOU ARE STORING THE REFRIGERANT IN?
- A.
YELLOW TOPS
- B.
WHITE TOPS
- C.
GREEN TOPS
- D.
GRAY TOPS
Correct Answer
A. YELLOW TOPSExplanation
The correct answer is YELLOW TOPS. When recovering R-22 refrigerant, the cylinder used for storing it should have yellow tops. This is because yellow is the designated color for cylinders used for storing R-22 refrigerant. The color-coding system helps to easily identify the type of refrigerant stored in the cylinder, ensuring proper handling and preventing cross-contamination.Rate this question:
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- 34.
IF UNLOADERS WERE TO FAIL IN THE UNLOADED POSITION, WHAT HAPPENS IN A SYSTEM USING RECIPROCATING COMPRESSOR?
- A.
THE EVAPORATOR WILL STARVE
- B.
CAUSE HIGH SUPERHEAT
- C.
NOT ENOUGH REFRIGERANT TO COIL
- D.
ALL OF THE ABOVE
Correct Answer
D. ALL OF THE ABOVEExplanation
If unloaders were to fail in the unloaded position in a system using a reciprocating compressor, all of the above consequences would occur. The evaporator will starve because there won't be enough refrigerant flowing through it. This will cause high superheat, which refers to the temperature of the refrigerant vapor above its saturation temperature. Additionally, there won't be enough refrigerant to the coil, leading to a decrease in cooling capacity and inefficient operation of the system.Rate this question:
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- 35.
WHEN THE TEMPERATURE AND THE LOAD INCREASE AND YOU NEED TO ADD ANOTHER PUMP ONLINE, YOU WOULD:
- A.
CLOSE BOTH SUCTION AND DISCHARGE
- B.
OPEN BOTH SUCTION AND DISCHARGE
- C.
OPEN SUCTION AND THROTTLE DISCHARGE
- D.
OPEN DISCHARGE BYPASS AND CLOSE SUCTION
Correct Answer
C. OPEN SUCTION AND THROTTLE DISCHARGEExplanation
When the temperature and the load increase and you need to add another pump online, you would open the suction and throttle the discharge. This means that you would allow the flow of fluid into the pump by opening the suction valve, while at the same time reducing the flow rate by partially closing the discharge valve. This is done to maintain the desired pressure and prevent overloading the system. By throttling the discharge, you can control the flow and prevent any potential damage or instability in the system.Rate this question:
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- 36.
WHEN A SYSTEM DOES NOT HAVE UNLOADERS, WHAT IS NEEDED?
- A.
OTHER CAPACITY CONTROL
- B.
VARIABLE INLET GUIDE VANES
- C.
AN ECONOMIZER
- D.
SOLENOID ON LIQUID LINE
Correct Answer
A. OTHER CAPACITY CONTROLExplanation
When a system does not have unloaders, other capacity control methods are needed. Unloaders are devices that regulate the refrigerant flow in a system to match the cooling load. Without unloaders, the system would not be able to adjust its capacity based on the demand, leading to inefficient operation. Therefore, other capacity control methods such as variable inlet guide vanes, an economizer, or a solenoid on the liquid line are required to ensure optimal performance and energy efficiency in the system.Rate this question:
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- 37.
WHEN AN EVAPORATOR IS NOT EQUIPPED WITH AN EQUALIZER LINE, YOU WOULD MOST LIKELY FIND:
- A.
FEELER BULB PLACED IN DIFFERENT AREA
- B.
A DISTRIBUTOR
- C.
AN AUTOMATIC EXPANSION VALVE
- D.
BOTH HIGH AND LOW SIDE PRESSURES IDENTICAL
Correct Answer
B. A DISTRIBUTORExplanation
When an evaporator is not equipped with an equalizer line, it is most likely that a distributor would be present. A distributor is used to evenly distribute the refrigerant flow to the different evaporator coils. Without an equalizer line, the distributor helps to ensure that each coil receives the same amount of refrigerant, preventing any imbalance in cooling performance.Rate this question:
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- 38.
WHEN YOU PLAN ON OVERHAULING A SYSTEM AND YOU HAVE RECOVERED ALL LIQUID REFRIGERANT, WHAT IS NEXT?
- A.
GO AHEAD AND DO THE WORK
- B.
RECOVER ALL VAPOR, THEN DO WORK
- C.
SEND LIQUID NITROGEN THROUGH
- D.
EVACUATE SYSTEM
Correct Answer
B. RECOVER ALL VAPOR, THEN DO WORKExplanation
After recovering all the liquid refrigerant, the next step is to recover all the vapor before proceeding with the work. This is important to ensure that all the refrigerant is properly removed from the system, preventing any potential leaks or contamination. Once all the vapor is recovered, then the work can be safely carried out.Rate this question:
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- 39.
WHEN THERE IS A 5 LB PRESSURE DROP ACROSS EVAPORATOR, YOU NEED AN EXTERNAL EQUALIZER LINE, WHAT HAPPENS IF IT DISCONNECTS
- A.
EXCESSIVE SUPERHEAT
- B.
EVAPORATOR WOULD STARVE
- C.
EVAPORATOR WOULD FLOOD
- D.
TEV WOULD NOT FUNCTION
Correct Answer
B. EVAPORATOR WOULD STARVEExplanation
If the external equalizer line disconnects when there is a 5 lb pressure drop across the evaporator, the evaporator would starve. This means that there would be a lack of refrigerant flow into the evaporator, leading to insufficient cooling and potentially causing the system to malfunction.Rate this question:
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- 40.
THE METERING DEVICE USED IN A CONDENSER IS A HIGH SIDE FLOAT, THIS DEVICE WILL:
- A.
CONTROL THE AMOUNT OF WATER IN CONDENSER
- B.
CONTROL THE AMOUNT OF REFRIGERANT IN CONDENSER
- C.
KEEPS A CONSTANT PRESSURE
- D.
KEEPS A CONSTANT TEMPERATURE
Correct Answer
B. CONTROL THE AMOUNT OF REFRIGERANT IN CONDENSERExplanation
The high side float metering device is used in a condenser to control the amount of refrigerant in the condenser. This device regulates the flow of refrigerant into the condenser, ensuring that the correct amount of refrigerant is present for the cooling process. By controlling the amount of refrigerant, the high side float helps maintain the efficiency and performance of the condenser.Rate this question:
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- 41.
IF A LOW SIDE FLOAT IS BEING USED:
- A.
PRESSURE WILL BE CONSTANT
- B.
IT WILL CONTROL REFRIGERANT FLOW
- C.
IT WILL CONTROL WATER FLOW
- D.
TEMPERATURE IS CONSTANT
Correct Answer
B. IT WILL CONTROL REFRIGERANT FLOWExplanation
A low side float is a device used in refrigeration systems to control the flow of refrigerant. It is designed to maintain a constant level of refrigerant in the evaporator by opening or closing a valve based on the level of refrigerant. When the refrigerant level is low, the float opens the valve to allow more refrigerant into the evaporator. Conversely, when the level is high, the float closes the valve to restrict the flow. Therefore, the correct answer is that a low side float will control the flow of refrigerant.Rate this question:
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- 42.
THE HEAT THAT BOILS OFF IN A CONDENSER IS:
- A.
LATENT HEAT
- B.
SENSIBLE HEAT
- C.
SUPERHEAT
- D.
ALL OF THE ABOVE
Correct Answer
A. LATENT HEATExplanation
The heat that boils off in a condenser is latent heat. This is because latent heat refers to the heat energy required to change the state of a substance without changing its temperature. In the case of a condenser, the heat energy is used to convert a vapor or gas into a liquid state, without changing the temperature of the substance. Therefore, the correct answer is latent heat.Rate this question:
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- 43.
THE CONDENSER THAT USES AIR AND WATER FOR COOLING IS THE:
- A.
AIR COOLED
- B.
WATER COOLED
- C.
EVAPORATIVE
- D.
BOTH A AND B ARE CORRECT
Correct Answer
C. EVAPORATIVEExplanation
The correct answer is EVAPORATIVE. An evaporative condenser uses a combination of air and water for cooling. It works by passing hot refrigerant gas through a coil, where water is sprayed onto the coil. The heat from the refrigerant causes the water to evaporate, which in turn cools the refrigerant. The cooled refrigerant then condenses back into a liquid state. This type of condenser is commonly used in air conditioning systems and industrial cooling processes.Rate this question:
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- 44.
A HERMETIC COMPRESSOR IS OPERATING WITH A LOW REFRIGERANT CHARGE. WHAT IS THE MOST LIKELY EFFECT THIS CONDITION WOULD HAVE ON THE COMPRESSOR?
- A.
HEAD PRESSURE WOULD RISE
- B.
COMPRESSOR WOULD OPERATE AT HIGHER TEMPERATURE
- C.
HAVE NO EFFECT ON THE COMPRESSOR
- D.
OIL PRESSURE WOULD RISE
Correct Answer
B. COMPRESSOR WOULD OPERATE AT HIGHER TEMPERATUREExplanation
When a hermetic compressor is operating with a low refrigerant charge, it means that there is not enough refrigerant in the system. This can lead to inadequate cooling and lubrication of the compressor. As a result, the compressor would have to work harder to maintain the desired cooling capacity, causing it to operate at a higher temperature. Therefore, the most likely effect of a low refrigerant charge on the compressor is that it would operate at a higher temperature.Rate this question:
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- 45.
A REFRIGERATION UNIT IS MEASURED IN:
- A.
WATTS
- B.
VOLTS
- C.
BTUs
- D.
TEMPERATURE
Correct Answer
C. BTUsExplanation
A refrigeration unit is measured in BTUs (British Thermal Units). BTUs are a unit of measurement used to quantify the amount of heat energy required to raise the temperature of one pound of water by one degree Fahrenheit. In the context of a refrigeration unit, BTUs are used to measure the cooling capacity of the unit. The higher the BTU rating, the more cooling power the unit has. Watts and volts are units of measurement for electrical power, while temperature is a measure of the degree of hotness or coldness of an object or environment.Rate this question:
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- 46.
A CENTRIFUGAL CHILLER HAS A SUCTION PRESSURE OF 18" HG VACUUM AND DISCHARGE PRESSURE OF 6 PSIG. WHAT IS THE COMPRESSION RATIO OF THIS UNIT?
- A.
3.50
- B.
2.96
- C.
1.75
- D.
2.76
Correct Answer
A. 3.50Explanation
The compression ratio of a centrifugal chiller can be calculated by dividing the discharge pressure by the suction pressure. In this case, the discharge pressure is given as 6 PSIG and the suction pressure is given as 18" HG vacuum. To convert the suction pressure from inches of mercury to PSIG, we need to use a conversion factor. The conversion factor is approximately 0.491, so the suction pressure in PSIG is calculated as 18" HG vacuum * 0.491 = 8.938 PSIG. Therefore, the compression ratio is 6 PSIG / 8.938 PSIG = 0.671.Rate this question:
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- 47.
WHAT IS A METHOD USED TO CALIBRATE A THERMOMETER?
- A.
PLACE THERMOMETER IN CUP OF ICE
- B.
PLACE THERMOMETER IN SUPERHEATED STEAM
- C.
LOWER TEMPERATURE ON THERMOMETER
- D.
RAISE TEMPERATURE ON THERMOMETER
Correct Answer
A. PLACE THERMOMETER IN CUP OF ICEExplanation
Placing the thermometer in a cup of ice is a method used to calibrate a thermometer because ice has a known temperature of 0 degrees Celsius or 32 degrees Fahrenheit. By placing the thermometer in the ice, it allows the thermometer to adjust to the temperature of the ice and ensures that it is accurately measuring the temperature. This method helps to verify the accuracy of the thermometer and allows for any necessary adjustments to be made.Rate this question:
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- 48.
IF HAD TO INSTALL A SOLENOID VALVE TO A SYSTEM WHICH USES 110 VOLTS AND NEEDED TO CONVERT IT TO 24 VOLTS, WHAT WOULD YOU USE?
- A.
STEP UP TRANSFORMER
- B.
STEP DOWN TRANSFORMER
- C.
AC TO DC RECTIFICATION
- D.
REWIRE CIRCUIT WITH SMALLER GAUGE WIRE
Correct Answer
B. STEP DOWN TRANSFORMERExplanation
A step-down transformer is used to convert a higher voltage to a lower voltage. In this case, the system uses 110 volts and needs to be converted to 24 volts, so a step-down transformer would be the appropriate choice. This transformer would reduce the voltage from 110 volts to 24 volts, allowing the solenoid valve to operate safely and effectively within the system.Rate this question:
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- 49.
IF YOU HAD 38°F IN THE EVAPORATOR, WHAT SHOULD YOUR SUCTION PRESSURE BE FOR R-22
- A.
66 PSIA
- B.
66 PSIG
- C.
76 PSIG
- D.
76 PSIA
Correct Answer
B. 66 PSIGExplanation
The correct answer is 66 PSIG. The suction pressure in an R-22 system should be measured in PSIG (pounds per square inch gauge). PSIG refers to the pressure above atmospheric pressure. Since the question states that the evaporator temperature is 38°F, which corresponds to a saturation pressure of 66 PSIG on the R-22 pressure-temperature chart, the suction pressure should be 66 PSIG.Rate this question:
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- 50.
AN OIL WITH LOW VISCOSITY WOULD:
- A.
NOT BE USED FOR REFRIGERATION
- B.
BE USED FOR ENGINE/MOTORS
- C.
BE USED FOR AIR CONDITIONING
- D.
BOTH B AND C ARE CORRECT
Correct Answer
A. NOT BE USED FOR REFRIGERATIONExplanation
An oil with low viscosity would not be used for refrigeration because refrigeration systems require oils with high viscosity to ensure proper lubrication and to prevent leakage. Low viscosity oils are more suitable for engine/motors and air conditioning systems as they allow for easier flow and reduce friction, improving the efficiency of these systems. Therefore, options B and C are correct.Rate this question:
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Current Version
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Mar 21, 2023Quiz Edited by
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Dec 02, 2015Quiz Created by
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