Refrigerant Machine Operator Test #2

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| By Catherine Halcomb

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WHAT IS A METHOD USED TO CALIBRATE A THERMOMETER?
- PLACE THERMOMETER IN CUP OF ICE
- PLACE THERMOMETER IN SUPERHEATED STEAM
- LOWER TEMPERATURE ON THERMOMETER
- RAISE TEMPERATURE ON THERMOMETER

About This Quiz

Incase you are a refrigerant machine operator and are in need of brushing up your knowledge and comprehension of this job then this is the quiz for you. It is designed to gauge how much you know.

Refrigerant Machine Operator Test #2 - Quiz

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2.

WHEN OPERATING A RECIPROCATING REFRIGERATION SYSTEM WITH A BELT DRIVEN COMPRESSOR, AN RMO NOTICES THAT ONE OF THE 4 BELTS IS BROKEN. OF THE FOLLOWING, THE MOST ADVISABLE COURSE OF ACTION FOR THE RMO WOULD BE TO
- PUT MORE GREASE ON THE REMAINING BELTS
- REPLACE ALL 4 BELTS WITH A NEW SET
- REPLACE THE BROKEN BELT ONLY
- OPERATE WITH THE 3 REMAINING BELTS
Correct Answer

A. REPLACE ALL 4 BELTS WITH A NEW SET

Explanation

When operating a reciprocating refrigeration system with a belt driven compressor, if one of the 4 belts is broken, the most advisable course of action for the RMO would be to replace all 4 belts with a new set. This is because the belts work together to drive the compressor and maintain the proper functioning of the system. Replacing only the broken belt may put additional strain on the remaining belts, leading to further damage or failure. Therefore, it is best to replace all the belts to ensure the system operates smoothly and efficiently.

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1
3.

OF THE FOLLOWING CHARACTERISTICS OF REFRIGERANT, THE ONE THAT BEST DESCRIBES REFRIGERANT 22 IS:
- ODORLESS WHEN MIXED WITH AIR
- AN ETHER LIKE ODOR WHEN MIXED WITH AIR
- EXPLOSIVE WHEN MIXED WITH AIR
- BOILS AT HIGHER TEMP THAT R-12
Correct Answer

A. ODORLESS WHEN MIXED WITH AIR

Explanation

Refrigerant 22 is described as odorless when mixed with air. This means that it does not have a distinct smell when it is in a gaseous state and mixed with air.

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2
4.

COPPER USED IN REFRIGERATION SYSTEMS, LIKE IN HEAT EXCHANGERS, BECAUSE?
- EASY FABRICATION
- EASY DURABILITY
- HIGH THERMAL CONDUCTIVITY
- FLEXIBILITY
Correct Answer

A. HIGH THERMAL CONDUCTIVITY

Explanation

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 common metals, making it an excellent choice for transferring heat efficiently in refrigeration systems. This property allows copper to quickly absorb and transfer heat, improving the overall performance and efficiency of the system.

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1
5.

A REFRIGERATION UNIT IS MEASURED IN:
- WATTS
- VOLTS
- BTUs
- TEMPERATURE
Correct Answer

A. BTUs

Explanation

A refrigeration unit is measured in BTUs (British Thermal Units). BTUs are a unit of measurement for heat energy. In the context of refrigeration, 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 electrical power, which are not directly related to the cooling capacity of a refrigeration unit. Temperature is a measure of the degree of hotness or coldness and is not used to measure the capacity of a refrigeration unit.

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1
6.

REGARDLESS OF SAFETY CLASSIFICATION OF THE REFRIGERANT IN USE, IN THE EVENT OF REFRIGERANT ESCAPE, THE RMO SHOULD BE AWARE OF:
- A REFRIGERANT FIRE
- REFRIGERANT POISONING
- OXYGEN DEPRIVATION
- ATMOSPHERIC SUPERHEATING
Correct Answer

A. OXYGEN DEPRIVATION

Explanation

In the event of a refrigerant escape, regardless of the safety classification of the refrigerant in use, the RMO should be aware of oxygen deprivation. When a refrigerant escapes, it can displace the oxygen in the surrounding area, leading to a decrease in oxygen levels. This can be dangerous for anyone in the vicinity, as it can cause symptoms such as dizziness, shortness of breath, and even loss of consciousness. Therefore, it is important for the RMO to be aware of this potential hazard and take appropriate measures to ensure the safety of everyone involved.

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2
7.

WHEN DRY BULB IS 75°F AND WET BULB IS 75°F:
- NOT POSSIBLE
- VERY LOW HUMIDITY
- THERMOMETER IS DEFECTIVE
- 100% RELATIVE HUMIDITY
Correct Answer

A. 100% RELATIVE HUMIDITY

Explanation

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 value of 100%.

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4
8.

THE REFRIGERATION UNIT WHICH YOU HAVE BEEN ASSIGNED TO IS BEING TAKEN OUT OF SERVICE FOR MAJOR REPAIRS. YOU HAVE BEEN ASSIGNED TO WITHDRAW REFRIGERANT FOR STORAGE IN SUITABLE CONTAINERS. ACCORDING TO THE NYC FIRE LAW HANDBOOK YOU MUST ENSURE THAT CONTAINERS:
- ARE APPROVED BY THE U.S. DEPT. OF TRANSPORTATION
- ARE APPROVED BY THE FACILITIES MANAGER
- DO NOT WEIGH MORE THAN 200 LBS WHEN FILLED
- DO NOT EXCEED 55 GALLONS IN CAPACITY
Correct Answer

A. ARE APPROVED BY THE U.S. DEPT. OF TRANSPORTATION

Explanation

The correct answer is "ARE APPROVED BY THE U.S. DEPT. OF TRANSPORTATION." According to the NYC Fire Law Handbook, when withdrawing refrigerant for storage, it is necessary to ensure that the containers used are approved by the U.S. Dept. of Transportation. This is important because the transportation of hazardous materials, such as refrigerants, is regulated by the DOT to ensure safety during transportation. By using approved containers, the risk of accidents or leaks during transportation is minimized.

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1
9.

COMPOUND GAUGES CAN MEASURE:
- ABOVE ATMOSPHERIC
- BELOW ATMOSPHERIC
- TEMPERATURE
- ALL OF THE ABOVE
Correct Answer

A. ALL OF THE ABOVE

Explanation

Compound gauges are designed to measure both above and below atmospheric pressure. They are commonly used in applications where a wide range of pressures need to be measured, such as in industrial processes or HVAC systems. Additionally, compound gauges can also be equipped with temperature sensors, allowing them to measure temperature as well. Therefore, the correct answer is "ALL OF THE ABOVE".

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10.

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
- TURN ON CHILLED WATER PUMPS AND OPEN THE BYPASS TO LIGHTER LOAD
- INSTALL LARGER FUSE TO TAKE THE INITIAL LOAD, AND THEN TURN ON THE COOLING TOWER FANS
- TURN ON CHILLED WATER PUMP, CONDENSER WATER PUMPS AND COOLING TOWER FANS
- SET THE THERMOSTAT A FEW DEGREES HIGHER
Correct Answer

A. TURN ON CHILLED WATER PUMP, CONDENSER WATER PUMPS AND COOLING TOWER FANS

Explanation

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 use of the reciprocating plant for air conditioning. To effectively cool the space, the chilled water pump needs to be turned on to circulate cold water through the system. The condenser water pumps are necessary to remove heat from the condenser, and the cooling tower fans help to dissipate the heat from the cooling tower. By turning on these components, the refrigeration machine operator can ensure proper cooling and maintain the desired temperature in the space.

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11.

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?
- STEP UP TRANSFORMER
- STEP DOWN TRANSFORMER
- AC TO DC RECTIFICATION
- REWIRE CIRCUIT WITH SMALLER GAUGE WIRE
Correct Answer

A. STEP DOWN TRANSFORMER

Explanation

A step-down transformer would be used to convert the voltage from 110 volts to 24 volts. A step-down transformer has more turns on the secondary coil than the primary coil, which results in a lower output voltage. This allows the voltage to be reduced from 110 volts to 24 volts, which is the desired voltage for the solenoid valve in the system.

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12.

WHAT REFRIGERANTS ARE YOU NOT ABLE TO DUMP?
- CFC
- HCFC
- HFC
- ANY REFRIGERANT CONTAINING CHLORINE OR FLUORINE
Correct Answer

A. ANY REFRIGERANT CONTAINING CHLORINE OR FLUORINE

Explanation

Refrigerants that contain chlorine or fluorine cannot be dumped. This is because these substances are harmful to the environment and contribute to the depletion of the ozone layer. CFCs (chlorofluorocarbons), HCFCs (hydrochlorofluorocarbons), and HFCs (hydrofluorocarbons) are all examples of refrigerants that contain chlorine or fluorine. Dumping these refrigerants can lead to the release of these harmful substances into the atmosphere, causing damage to the ozone layer and contributing to climate change. Therefore, it is important to properly dispose of refrigerants containing chlorine or fluorine to prevent environmental harm.

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13.

ACCORDING TO THE NYC FIRE CODE CLASSIFICATION OF REFRIGERANTS, AMMONIA AND SULpHER DIOXIDE AR GROUPED INTO:
- GROUP 2
- GROUP 4
- GROUP 1
- GROUP 3
Correct Answer

A. GROUP 2

Explanation

According to the NYC Fire Code classification of refrigerants, ammonia and sulfur dioxide are grouped into Group 2.

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14.

AN ELECTRIC MOTOR THAT IS RATED AT 3 HP WILL?
- USE THREE PHASE
- NEED A CAPACITOR
- USE SINGLE PHASE
- WILL RUN WITH REDUCED POWER OUTPUT
Correct Answer

A. USE THREE PHASE

Explanation

An electric motor that is rated at 3 HP will use three-phase power. Three-phase power is commonly used for motors with higher power ratings as it provides a more efficient and balanced power supply compared to single-phase power. This allows the motor to operate at its full power output without any reduction in performance. A capacitor is not needed in this case as it is primarily used to improve power factor and correct phase imbalances in single-phase motors.

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2
15.

THE ADVANTAGE OF FORCED DRAFT OVER NATURAL DRAFT COOLING TOWER IS:
- THE POSSIBILITY OF LOWER WATER OUT TEMP
- THERE IS NO DEPENDENCE ON NATURAL WIND VELOCITY
- USE OF A SMALLER TOWER SIZE
- ALL OF THE ABOVE
Correct Answer

A. ALL OF THE ABOVE

Explanation

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 are not dependent on natural wind velocity, allowing for more consistent cooling performance. 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.

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1
16.

WHEN YOU PLAN ON OVERHAULING A SYSTEM AND YOU HAVE RECOVERED ALL LIQUID REFRIGERANT, WHAT IS NEXT?
- GO AHEAD AND DO THE WORK
- RECOVER ALL VAPOR, THEN DO WORK
- SEND LIQUID NITROGEN THROUGH
- EVACUATE SYSTEM
Correct Answer

A. RECOVER ALL VAPOR, THEN DO WORK

Explanation

After recovering all the liquid refrigerant from the system, the next step is to recover all the vapor before proceeding with the work. This ensures that all the refrigerant is safely removed from the system, preventing any potential leaks or hazards. Once all the vapor is recovered, the work can be carried out without any risk of refrigerant contamination or damage.

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1
17.

REGARDING FIRE SAFETY ANSI/ASHRAE, WHICH CLASSIFICATION INDICATES THE LEAST FLAMMABILITY AND LEAST TOXICITY?
- A1
- B2
- A2
- B1
Correct Answer

A. A1

Explanation

The classification A1 indicates the least flammability and least toxicity in terms of fire safety according to ANSI/ASHRAE standards.

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2
18.

THE RATIO OF ACTUAL PRESSURE OF WATER VAPOR IN THE ATMOSpHERE TO THE SATURATION PRESSURE / TEMPERATURE IS CALLED:
- ABSOLUTE HUMIDITY
- HUMIDITY EFFECT
- PARTIAL PRESSURE
- RELATIVE HUMIDITY
Correct Answer

A. RELATIVE HUMIDITY

Explanation

Relative humidity is the ratio of the actual pressure of water vapor in the atmosphere to the saturation pressure/temperature. It represents the amount of moisture in the air relative to the maximum amount it could hold at a given temperature. It is expressed as a percentage and is commonly used to describe how "humid" or "dry" the air feels.

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1
19.

IF UNLOADERS WERE TO FAIL IN THE UNLOADED POSITION, WHAT HAPPENS IN A SYSTEM USING RECIPROCATING COMPRESSOR?
- THE EVAPORATOR WILL STARVE
- CAUSE HIGH SUPERHEAT
- NOT ENOUGH REFRIGERANT TO COIL
- ALL OF THE ABOVE
Correct Answer

A. ALL OF THE ABOVE

Explanation

If the unloaders were to fail in the unloaded position in a system using a reciprocating compressor, several issues would occur. Firstly, the evaporator would starve, meaning that it would not receive enough refrigerant to properly cool the system. This would lead to high superheat, which is the temperature of the refrigerant vapor above its saturation temperature. Lastly, there would not be enough refrigerant flowing through the coil, further exacerbating the cooling issues. Therefore, all of the above statements are true and would happen if the unloaders failed in the unloaded position.

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20.

AN OPERATOR SUSPECTS THAT A VERTICAL CHECK VALVE ON A DISCHARGE OF A CENTRIFUGAL PUMP IS DEFECTIVE, THIS IS A CONDENSER PUMP AND ONE OF THE THREE PUMPS IN PARALLEL. IF THE SUSPICION IS TRUE AND THE CHECK VALVE FAILS TO SEAT WHEN REQUIRED, THE PUMP AND CONNECTING PIPING WILL MOST LIKE BE DAMAGED WHEN:
- LUBRICATING THE PUMP
- AFTER HAVING BLED AIR FROM THE PUMP CASING PETCOCK
- STARTING UP AN ADDITIONAL PUMP
- SHUTTING THE PUMP DOWN
Correct Answer

A. STARTING UP AN ADDITIONAL PUMP

Explanation

If the vertical check valve on the discharge of the centrifugal pump is defective and fails to seat when required, starting up an additional pump can cause damage to the pump and connecting piping. This is because starting up an additional pump will increase the pressure in the system, and without a properly functioning check valve, the increased pressure can cause backflow and damage the pump and piping.

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2
21.

AN OPERATOR NOTICES THAT A CENTRIFUGAL PUMP OPERATES SATISFACTORILY WHEN DELIVERING AT FULL DISCHARGE, BUT LOSES WATER FLOW IF THROTTLED. THE OPERATOR WOULD MOST ACCURATELY ASSUME THAT THIS CONDITION IS DUE TO:
- WATER HAMMER
- CLOGGED STRAINER IN PUMP INLET
- POOR BEARING LUBRICATION
- AIR LEAKS IN THE PUMP
Correct Answer

A. CLOGGED STRAINER IN PUMP INLET

Explanation

The most accurate assumption for the operator is that the condition is due to a clogged strainer in the pump inlet. This is because when the pump is delivering at full discharge, there is enough pressure to overcome the obstruction caused by the clogged strainer. However, when the flow is throttled, the reduced pressure causes the clog to have a greater impact, resulting in a loss of water flow.

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22.

ASSUMING THAT A REFRIGERATION PLANT USES A HORIZONTAL SHELL AND TUBE CONDENSER WITH THE WATER IN THE TUBES AND THE REFRIGERANT IN THE SHELL. IN CONTROLLING THE OPERATION OF THE CONDENSER, THE OPERATOR SHOULD TAKE INTO ACCOUNT THAT MOST LIKELY THE HEAT TRANSFER RATE BTU/PER SQ FT PER SECOND IN THE CONDENSER WILL:
- SHOW THE LEAST BENEFIT FOR DESCALING TUBES AT HIGH WATER VELOCITIES
- INCREASE WITH THE VELOCITY OF THE WATER IN THE TUBES
- INCREASE THE LOWER LOG MEAN TEMPERATURE DIFFERENCE
- SHOW ONLY A SMALL INCREASE IF THE TUBES ARE DESCALED
Correct Answer

A. INCREASE WITH THE VELOCITY OF THE WATER IN THE TUBES

Explanation

The correct answer is that the heat transfer rate in the condenser will increase with the velocity of the water in the tubes. This is because higher water velocity promotes better mixing and turbulence, which enhances heat transfer between the refrigerant in the shell and the water in the tubes. As a result, increasing the water velocity can improve the overall efficiency and performance of the condenser.

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23.

SHELL AND TUBE CONDENSERS HAVE THE ADVANTAGE OF:
- REMOVING HEADS FOR CLEANING THE WATER SIDES OF THE TUBES
- THE REFRIGERANT CONNECTIONS DOES NOT HAVE TO BE DISRUPTED
- USING ACID FOR CLEANING
- BOTH A AND B ARE CORRECT
Correct Answer

A. BOTH A AND B ARE CORRECT

Explanation

Both options A and B are correct because shell and tube condensers have the advantage of being able to remove the heads for cleaning the water sides of the tubes and the refrigerant connections do not have to be disrupted. This allows for easier maintenance and cleaning of the condenser, ensuring optimal performance and efficiency.

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24.

THE ACCESSORIES ON THE LIQUID LINE ARE IN WHAT ORDER?
- SOLENOID VALVE, DRIER, AND SIGHT-GLASS
- RECEIVER, DRIER, SOLENOID VALVE, AND SIGHT-GLASS
- MUFFLER, DRIER, SIGHT-GLASS AND SOLENOID VALVE
- ACCUMULATOR, MUFFLER, DRIER, SIGHT-GLASS
Correct Answer

A. RECEIVER, DRIER, SOLENOID VALVE, AND SIGHT-GLASS

Explanation

The correct order of the accessories on the liquid line is receiver, drier, solenoid valve, and sight-glass. This order ensures that the refrigerant flows properly through the system. The receiver is responsible for storing excess refrigerant and preventing liquid from entering the compressor. The drier removes moisture and contaminants from the refrigerant. The solenoid valve controls the flow of refrigerant into the evaporator. The sight-glass allows technicians to visually inspect the refrigerant for any issues.

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25.

IN A 3 STAGE CENTRIFUGAL CHILLER, WHAT HAPPENS TO THE PRESSURE AS IT REACHES THE FINAL STAGE?
- INCREASES
- DECREASES
- SPEED CHANGES NOT PRESSURE
- VOLUME CHANGES NOT PRESSURE
Correct Answer

A. INCREASES

Explanation

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 progresses through the system. As the refrigerant moves from one stage to the next, it undergoes compression, which increases its pressure. Therefore, by the time it reaches the final stage, the pressure has significantly increased.

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2
26.

IF A LOW SIDE FLOAT IS BEING USED:
- PRESSURE WILL BE CONSTANT
- IT WILL CONTROL REFRIGERANT FLOW
- IT WILL CONTROL WATER FLOW
- TEMPERATURE IS CONSTANT
Correct Answer

A. IT WILL CONTROL REFRIGERANT FLOW

Explanation

A low side float is a device used in refrigeration systems to control the flow of refrigerant. It is typically installed on the suction line of the system and works by maintaining a constant level of refrigerant in the evaporator. As the refrigerant evaporates and flows through the system, the float valve opens or closes to regulate the amount of refrigerant entering the evaporator. This helps to maintain a consistent and controlled flow of refrigerant, ensuring efficient operation of the system.

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27.

OIL FLASHPOINT TEMPERATURE IN THE COMPRESSOR SHOULD BE:
- LOWER THAN THE HEAT OF COMPRESSION
- HIGHER THAN THE HEAT OF COMPRESSION
- EQUAL TO THE HEAT OF COMPRESSION
- EQUAL TO THE HEAT ABSORBED
Correct Answer

A. HIGHER THAN THE HEAT OF COMPRESSION

Explanation

The flashpoint temperature of oil in the compressor should be higher than the heat of compression. This is because the flashpoint temperature refers to the minimum temperature at which the oil vaporizes enough to form an ignitable mixture in the air. If the flashpoint temperature is lower than the heat of compression, there is a risk of the oil vaporizing and igniting within the compressor, which can lead to a fire or explosion. Therefore, it is important for the flashpoint temperature to be higher than the heat of compression to ensure safe operation of the compressor.

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28.

THE FOLLOWING MOST ACCURATE STATEMENT REGARDING COMPRESSOR MOTORS THAT RUN IN REFRIGERANT ATMOSpHERE IS THAT THEY:
- MAY USE INTERNAL RUBBER CUSHIONS
- MAY BE REPAIRED ON SITE WHEN THEY MALFUNCTION
- USE MATERIALS TAILORED TO THE REFRIGERANT
- USE SAME MATERIALS A PUMP IN AIR
Correct Answer

A. USE MATERIALS TAILORED TO THE REFRIGERANT

Explanation

Compressor motors that run in a refrigerant atmosphere use materials that are specifically designed and tailored to the properties of the refrigerant. This is important because different refrigerants have different chemical compositions and characteristics, such as temperature and pressure ranges. Therefore, using materials that are compatible with the specific refrigerant being used ensures optimal performance and prevents any potential damage or malfunction.

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1
29.

IN ADDITION TO REGULATING THE REFRIGERANT FLOW ACCORDING TO THE NEEDS OF THE SYSTEM, METERING DEVICES ALSO SERVE TO:
- INCREASE COMPRESSOR CAPACITY
- HOLD SYSTEM TO A CONSTANT LOAD
- RESTRICT FLOW OF REFRIGERANT FROM THE HIGH SIDE TO LOW SIDE
- SHED LOAD AS LOAD INCREASES
Correct Answer

A. RESTRICT FLOW OF REFRIGERANT FROM THE HIGH SIDE TO LOW SIDE

Explanation

Metering devices serve to restrict the flow of refrigerant from the high side to the low side. This restriction is necessary to maintain the proper pressure and temperature levels in the system. By controlling the flow of refrigerant, the metering device ensures that the refrigerant is properly distributed throughout the system and that the evaporator operates at the correct temperature. This helps to optimize the overall efficiency and performance of the refrigeration system.

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30.

THE RUPTURE DISK IS ALWAYS PIPED INTO THE
- HIGH SIDE
- LOW SIDE
- EITHER SIDE OF SYSTEM
- NEITHER SIDE SYSTEM
Correct Answer

A. LOW SIDE

Explanation

The rupture disk is always piped into the low side of the system. This is because the low side of the system is where the pressure is lower, and the rupture disk is designed to burst when the pressure exceeds a certain limit. By piping it into the low side, it ensures that if the pressure becomes too high, the disk will rupture and release the excess pressure safely.

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2
31.

A FUSIBLE PLUG MELTS AT
- 450°F
- 280°F
- 212°F
- 800°F
Correct Answer

A. 280°F

Explanation

A fusible plug is designed to melt at a specific temperature in order to prevent excessive pressure buildup in a system. In this case, the correct answer is 280°F. When the temperature reaches this point, the fusible plug will melt, allowing the pressure to be released and preventing any potential damage or danger.

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32.

HOW MANY BTUs WOULD BE REMOVED IN A 30 TON SYSTEM?
- 12,000 PER HOUR
- 360,000 PER MINUTE
- 12,000 PER MINUTE
- 360,000 PER HOUR
Correct Answer

A. 360,000 PER HOUR

Explanation

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 per minute multiplied by 60 minutes, which equals 360,000 BTUs per hour.

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33.

IF THE LOW PRESSURE CUTOUT CYCLES THE COMPRESSOR OFF, WHAT STARTS THE COMPRESSOR AGAIN?
- SOLENOID VALVE
- HIGH PRESSURE CUT OUT
- LOW PRESSURE CUT OUT
- THERMOSTAT
Correct Answer

A. LOW PRESSURE CUT OUT

Explanation

The low pressure cut out is responsible for cycling the compressor off when the pressure falls below a certain threshold. Once the compressor is cycled off, it needs a mechanism to start again. The low pressure cut out is designed to do just that. It detects when the pressure has reached a safe level and sends a signal to start the compressor again. Therefore, the low pressure cut out is the correct answer for what starts the compressor again.

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2
34.

THE SUCTION AND DISCHARGE VALVE IN A RECIPROCATING COMPRESSOR ARE POSITIONED:
- OVER VALVE PLATE
- UNDER VALVE PLATE
- BOTH UNDER AND OVER VALVE PLATE
- NONE OF THE ABOVE
Correct Answer

A. BOTH UNDER AND OVER VALVE PLATE

Explanation

In a reciprocating compressor, the suction and discharge valves are positioned both under and over the valve plate. This means that there are valves located on both the top and bottom sides of the valve plate. This design allows for efficient intake of gas during the suction stroke and effective expulsion of compressed gas during the discharge stroke. By having valves on both sides of the valve plate, the compressor can achieve higher compression ratios and better overall performance.

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4
35.

THE DIVIDING LINE BETWEEN THE HIGH AND LOW SIDES OF THE REFRIGERATION SYSTEM IS
- THE CONNECTION BETWEEN THE COMPRESSOR AND CONDENSER
- NEEDLE VALVE MECHANISM
- COMPRESSOR OUTLET AND THE ORIFICE OF THE METERING DEVICE
- CENTER PLATE OF THE REFRIGERATION MECHANISM
Correct Answer

A. COMPRESSOR OUTLET AND THE ORIFICE OF THE METERING DEVICE

Explanation

The dividing line between the high and low sides of the refrigeration system is the connection between the compressor outlet and the orifice of the metering device. This is where the high-pressure, high-temperature refrigerant gas from the compressor transitions to the low-pressure, low-temperature refrigerant liquid as it enters the evaporator. The orifice of the metering device controls the flow rate of the refrigerant into the evaporator, allowing for the desired cooling effect to be achieved.

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2
36.

AN OPERATOR OBSERVES A READING OF 60°C ON A REFRIGERATING UNIT. THE SAME READING IN FAHRENHEIT SCALE WOULD BE CLOSER TO
- 140
- 185
- 155
- 170
Correct Answer

A. 140

Explanation

To convert Celsius to Fahrenheit, you can use the formula F = (C * 9/5) + 32. In this case, the operator observed a reading of 60°C. Plugging this value into the formula, we get F = (60 * 9/5) + 32 = 140. Therefore, the reading in Fahrenheit scale would be closer to 140.

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2
37.

WHEN THE TEMPERATURE AND THE LOAD INCREASE AND YOU NEED TO ADD ANOTHER PUMP ONLINE, YOU WOULD:
- CLOSE BOTH SUCTION AND DISCHARGE
- OPEN BOTH SUCTION AND DISCHARGE
- OPEN SUCTION AND THROTTLE DISCHARGE
- OPEN DISCHARGE BYPASS AND CLOSE SUCTION
Correct Answer

A. OPEN SUCTION AND THROTTLE DISCHARGE

Explanation

When the temperature and load increase and another pump needs to be added online, opening the suction and throttling the discharge is the correct action to take. Opening the suction allows fluid to be drawn into the pump, while throttling the discharge restricts the flow and pressure to match the requirements of the system. This ensures that the additional pump can handle the increased temperature and load without causing any disruptions or damage to the system.

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1
38.

THE CYLINDER UNLOADER CONTROLS CAPACITY, IS THERE ANY OTHER FUNCTION IT MAY HAVE?
- ASSIST WITH COMPRESSOR SHUT DOWN
- ASSIST WITH COMPRESSOR START UP
- THERE IS NO OTHER FUNCTION
- RELEASES PRESSURE
Correct Answer

A. ASSIST WITH COMPRESSOR START UP

Explanation

The cylinder unloader controls capacity by assisting with the compressor start up. This means that it helps the compressor to start running smoothly and efficiently. It may have other functions as well, but the given options do not mention any other functions. Therefore, the correct answer is that it assists with compressor start up.

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39.

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
- CAPACITOR
- VOLTMETER
- OHMMETER
- AMMETER
Correct Answer

A. OHMMETER

Explanation

The 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 an ohmmeter. An ohmmeter is used to measure the resistance of a circuit or component. By using an ohmmeter, the operator can check the resistance of the motor windings. If the windings are shorted, the resistance reading will be very low or close to zero. This would confirm the suspicion that the shorted motor windings are causing the motor overloads to trip.

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1
40.

LATENT HEAT AND REFRIGERATION EFFECT ARE USUALLY LISTED AS REFRIGERANT PROPERTIES. THE REFRIGERATING EFFECT IS ALSO ALWAYS A LOWER VALUE THAN THE LATENT HEAT BECAUSE THE:
- HEAT REQUIRED TO COOL THE REFRIGERANT FROM COMPRESSOR DISCHARGE TO EVAPORATIVE TEMPERATURE IS SUBTRACTED FROM LATENT HEAT
- REFRIGERANT LATENT HEAT IS DIVIDED BY SPECIFIC GRAVITY OF THE REFRIGERANT
- REFRIGERANT CRITICAL TEMPERATURE IS FACTORED INTO THE CALCULATION OF THE REFRIGERATING EFFECT
- REFRIGERANT LATENT HEAT IS DIVIDED BY TH REFRIGERANT CIRCULATION RATE
Correct Answer

A. HEAT REQUIRED TO COOL THE REFRIGERANT FROM COMPRESSOR DISCHARGE TO EVAPORATIVE TEMPERATURE IS SUBTRACTED FROM LATENT HEAT

Explanation

The refrigerating effect is always a lower value than the latent heat because the heat required to cool the refrigerant from compressor discharge to evaporative temperature is subtracted from the latent heat. This means that some of the latent heat is used to cool the refrigerant, reducing the overall refrigerating effect.

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41.

ASSUME THAT A NEW VALVE PLATE HAS BEEN INSTALLED WHILE THEY ARE REPAIRING A RECIPROCATING COMPRESSOR IN A REFRIGERATING PLANT. THE INSTALLATION OF A NEW VALVE PLATE WILL REQUIRE THE REPLACEMENT OF
- ALL VALVE PLATES, SPRINGS AND SOME VALVE SEATS
- ALL VALVE AND VALVE SEATS
- VALVE SEATS ONLY
- SUCTION VALVES ONLY
Correct Answer

A. ALL VALVE AND VALVE SEATS

Explanation

When a new valve plate is installed during the repair of a reciprocating compressor in a refrigerating plant, it is necessary to replace all valve plates, springs, and some valve seats. This is because the valve plate is a crucial component that regulates the flow of refrigerant in and out of the compressor cylinders. By replacing all valve plates, springs, and some valve seats, the compressor can operate efficiently and effectively, ensuring proper refrigeration in the plant.

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42.

AN OPERATOR READS THE VALVE TAG ON A PRESSURE RELIEF VALVE AND NOTICES THAT THE VALVE IS SET TO UNSEAT AT AN EVAPORATOR PRESSURE OF 15 PSI, THE CORRESPONDING SET PRESSURE IN INCHES HG IS
- 18
- 14
- 20
- 30.3
Correct Answer

A. 30.3
43.

FLOODED EVAPORATORS HAVE HIGH HEAT TRANSFER PER SQUARE FOOT, WHAT MAY BE A DISADVANTAGE?
- REQUIRES A SMALLER CHARGE
- REQUIRES A HIGHER CHARGE
- REQUIRES A USE OF A TXV FOR PROPER FEED
- WATER HAS TO BE DRAINED DAILY
Correct Answer

A. REQUIRES A HIGHER CHARGE

Explanation

Flooded evaporators require a higher charge of refrigerant compared to other types of evaporators. This means that a larger amount of refrigerant is needed to fill the evaporator, which can be a disadvantage in terms of cost and environmental impact. A higher charge also increases the risk of refrigerant leaks and the need for regular maintenance and monitoring.

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44.

THE METERING DEVICE USED IN A CONDENSER IS A HIGH SIDE FLOAT, THIS DEVICE WILL:
- CONTROL THE AMOUNT OF WATER IN CONDENSER
- CONTROL THE AMOUNT OF REFRIGERANT IN CONDENSER
- KEEPS A CONSTANT PRESSURE
- KEEPS A CONSTANT TEMPERATURE
Correct Answer

A. CONTROL THE AMOUNT OF REFRIGERANT IN CONDENSER

Explanation

The high side float metering device is used to control the amount of refrigerant in the condenser. It regulates the flow of refrigerant into the condenser, ensuring that the correct amount is present for the cooling process. This helps to maintain the efficiency and performance of the condenser by preventing an excessive or insufficient amount of refrigerant from entering the system.

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45.

REGARDING THE PUMP BELOW ELEMENTS A, B, C, D, AND E CORRESPOND TO THE FOLLOWING:
- 90° REDUCING ELBOW, PUMP DISCHARGE, PUMP CASING, PUMP SUCTION, VIBRATION REDUCER
- 90° REDUCING ELBOW, PUMP SUCTION, PUMP CASING, PUMP DISCHARGE, CHECK VALVE
- 45° REDUCING ELBOW, PUMP SUCTION, MOTOR HOUSING,PUMP DISCHARGE, CHECK VALVES
- STRAIGHT 90, PUMP CASING, MOTOR HOUSING, REDUCING ELBOW, VIBRATION ELIMINATOR
Correct Answer

A. 90° REDUCING ELBOW, PUMP SUCTION, PUMP CASING, PUMP DISCHARGE, CHECK VALVE

Explanation

The correct answer is 90° REDUCING ELBOW, PUMP SUCTION, PUMP CASING, PUMP DISCHARGE, CHECK VALVE. This is because the given elements correspond to the different parts of the pump system. The 90° reducing elbow is a fitting used to change the direction of the flow. The pump suction is the inlet of the pump where the fluid is drawn in. The pump casing is the enclosure that houses the impeller and volute. The pump discharge is the outlet where the fluid is discharged. The check valve is a device that allows the flow of fluid in only one direction.

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46.

AN OPERATOR CONFIRMS THAT A CHILLER WATER PUMP IN A REFRIGERATING SYSTEM EMPLOYING R-123 IS CAVITATING, OF THE FOLLOWING, THE MOST LIKELY CAUSE FOR THIS CONDITION IS
- MALFUNCTIONING OF THE WATER MAKE UP FLOAT VALVE
- TOO MUCH TIME IN BETWEEN PUMP SERVICING
- OPERATING AT SUSTAINED HIGH LOADS
- LOWERING THE CHILLED WATER TEMPERATURE
Correct Answer

A. MALFUNCTIONING OF THE WATER MAKE UP FLOAT VALVE

Explanation

The most likely cause for the chiller water pump to be cavitating is the malfunctioning of the water make up float valve. A float valve is responsible for regulating the water level in the chiller system. If it malfunctions, it can lead to an inadequate water supply, causing the pump to cavitate. Cavitation occurs when the pressure in the pump drops below the vapor pressure of the refrigerant, causing bubbles to form and collapse, leading to damage and reduced efficiency of the pump.

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47.

WHILE DOING A ROUTINE INSPECTION, THE RMO NOTICED THE BULB OF THE TEV ON THE FLOOR, THE OPERATOR SHOULD ATTACH THE BULB AT:
- CENTER OF THE COIL
- EXPANSION VALVE OUTLET
- END OF COIL
- 3/4 AWAY TOWARDS THE END OF THE COIL
Correct Answer

A. END OF COIL

Explanation

The bulb of the TEV (Thermostatic Expansion Valve) should be attached at the end of the coil. This is because the bulb is responsible for sensing the temperature of the refrigerant and controlling the flow of refrigerant into the evaporator coil. Placing the bulb at the end of the coil ensures that it is in close proximity to the refrigerant entering the coil, allowing for accurate temperature sensing and control.

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48.

IF YOU HAVE 62 PSI AT 35°F AND 70 PSI AT 45°F, WHAT WOULD 38°F BE?
- 66
- 64.4
- 65
- 62
Correct Answer

A. 64.4

Explanation

The given question is asking for the pressure at 38°F based on the given pressures at 35°F and 45°F. To find the pressure at 38°F, we can use the concept of linear interpolation. Since the temperature is increasing, we can assume that the pressure is also increasing linearly. By calculating the slope using the given data, we can determine the pressure at 38°F. The slope is (70 PSI - 62 PSI) / (45°F - 35°F) = 0.8 PSI/°F. Now, we can calculate the pressure at 38°F by using the formula: pressure at 38°F = 62 PSI + (0.8 PSI/°F) * (38°F - 35°F) = 64.4 PSI. Therefore, the correct answer is 64.4.

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49.

WHEN A COMPRESSOR IS SAID TO HAVE A SAFETY HEAD THIS MEANS
- COMPRESSOR OPERATES WITH NORMAL PRESSURES
- COMPRESSOR OPERATES WITH LOW PRESSURES
- COMPRESSOR HAS PRESSURE RELIEF VALVE
- COMPRESSOR HAS HIGH PRESSURE CUT OUT
Correct Answer

A. COMPRESSOR HAS PRESSURE RELIEF VALVE

Explanation

When a compressor is said to have a safety head, it means that the compressor has a pressure relief valve. This valve is designed to release excess pressure in the compressor system to prevent any damage or failure. The pressure relief valve ensures that the pressure inside the compressor does not exceed safe limits, protecting both the compressor and the surrounding equipment or system.

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Quiz Review Timeline (Updated): Mar 22, 2023 +

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

Current Version
Mar 22, 2023

Quiz Edited by
ProProfs Editorial Team
Feb 09, 2014

Quiz Created by
Catherine Halcomb

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Refrigerant Machine Operator Test #2

WHAT IS A METHOD USED TO CALIBRATE A THERMOMETER?

Quiz Preview

WHEN OPERATING A RECIPROCATING REFRIGERATION SYSTEM WITH A BELT DRIVEN COMPRESSOR, AN RMO NOTICES THAT ONE OF THE 4 BELTS IS BROKEN. OF THE FOLLOWING, THE MOST ADVISABLE COURSE OF ACTION FOR THE RMO WOULD BE TO

OF THE FOLLOWING CHARACTERISTICS OF REFRIGERANT, THE ONE THAT BEST DESCRIBES REFRIGERANT 22 IS:

COPPER USED IN REFRIGERATION SYSTEMS, LIKE IN HEAT EXCHANGERS, BECAUSE?

A REFRIGERATION UNIT IS MEASURED IN:

REGARDLESS OF SAFETY CLASSIFICATION OF THE REFRIGERANT IN USE, IN THE EVENT OF REFRIGERANT ESCAPE, THE RMO SHOULD BE AWARE OF:

WHEN DRY BULB IS 75°F AND WET BULB IS 75°F:

THE REFRIGERATION UNIT WHICH YOU HAVE BEEN ASSIGNED TO IS BEING TAKEN OUT OF SERVICE FOR MAJOR REPAIRS. YOU HAVE BEEN ASSIGNED TO WITHDRAW REFRIGERANT FOR STORAGE IN SUITABLE CONTAINERS. ACCORDING TO THE NYC FIRE LAW HANDBOOK YOU MUST ENSURE THAT CONTAINERS:

COMPOUND GAUGES CAN MEASURE:

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

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?

WHAT REFRIGERANTS ARE YOU NOT ABLE TO DUMP?

ACCORDING TO THE NYC FIRE CODE CLASSIFICATION OF REFRIGERANTS, AMMONIA AND SULpHER DIOXIDE AR GROUPED INTO:

AN ELECTRIC MOTOR THAT IS RATED AT 3 HP WILL?

THE ADVANTAGE OF FORCED DRAFT OVER NATURAL DRAFT COOLING TOWER IS:

WHEN YOU PLAN ON OVERHAULING A SYSTEM AND YOU HAVE RECOVERED ALL LIQUID REFRIGERANT, WHAT IS NEXT?

REGARDING FIRE SAFETY ANSI/ASHRAE, WHICH CLASSIFICATION INDICATES THE LEAST FLAMMABILITY AND LEAST TOXICITY?

THE RATIO OF ACTUAL PRESSURE OF WATER VAPOR IN THE ATMOSpHERE TO THE SATURATION PRESSURE / TEMPERATURE IS CALLED:

IF UNLOADERS WERE TO FAIL IN THE UNLOADED POSITION, WHAT HAPPENS IN A SYSTEM USING RECIPROCATING COMPRESSOR?

AN OPERATOR NOTICES THAT A CENTRIFUGAL PUMP OPERATES SATISFACTORILY WHEN DELIVERING AT FULL DISCHARGE, BUT LOSES WATER FLOW IF THROTTLED. THE OPERATOR WOULD MOST ACCURATELY ASSUME THAT THIS CONDITION IS DUE TO:

SHELL AND TUBE CONDENSERS HAVE THE ADVANTAGE OF:

THE ACCESSORIES ON THE LIQUID LINE ARE IN WHAT ORDER?

IN A 3 STAGE CENTRIFUGAL CHILLER, WHAT HAPPENS TO THE PRESSURE AS IT REACHES THE FINAL STAGE?

IF A LOW SIDE FLOAT IS BEING USED:

OIL FLASHPOINT TEMPERATURE IN THE COMPRESSOR SHOULD BE:

THE FOLLOWING MOST ACCURATE STATEMENT REGARDING COMPRESSOR MOTORS THAT RUN IN REFRIGERANT ATMOSpHERE IS THAT THEY:

IN ADDITION TO REGULATING THE REFRIGERANT FLOW ACCORDING TO THE NEEDS OF THE SYSTEM, METERING DEVICES ALSO SERVE TO:

THE RUPTURE DISK IS ALWAYS PIPED INTO THE

A FUSIBLE PLUG MELTS AT

HOW MANY BTUs WOULD BE REMOVED IN A 30 TON SYSTEM?

IF THE LOW PRESSURE CUTOUT CYCLES THE COMPRESSOR OFF, WHAT STARTS THE COMPRESSOR AGAIN?

THE SUCTION AND DISCHARGE VALVE IN A RECIPROCATING COMPRESSOR ARE POSITIONED:

THE DIVIDING LINE BETWEEN THE HIGH AND LOW SIDES OF THE REFRIGERATION SYSTEM IS

AN OPERATOR OBSERVES A READING OF 60°C ON A REFRIGERATING UNIT. THE SAME READING IN FAHRENHEIT SCALE WOULD BE CLOSER TO

WHEN THE TEMPERATURE AND THE LOAD INCREASE AND YOU NEED TO ADD ANOTHER PUMP ONLINE, YOU WOULD:

THE CYLINDER UNLOADER CONTROLS CAPACITY, IS THERE ANY OTHER FUNCTION IT MAY HAVE?

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

LATENT HEAT AND REFRIGERATION EFFECT ARE USUALLY LISTED AS REFRIGERANT PROPERTIES. THE REFRIGERATING EFFECT IS ALSO ALWAYS A LOWER VALUE THAN THE LATENT HEAT BECAUSE THE:

ASSUME THAT A NEW VALVE PLATE HAS BEEN INSTALLED WHILE THEY ARE REPAIRING A RECIPROCATING COMPRESSOR IN A REFRIGERATING PLANT. THE INSTALLATION OF A NEW VALVE PLATE WILL REQUIRE THE REPLACEMENT OF

AN OPERATOR READS THE VALVE TAG ON A PRESSURE RELIEF VALVE AND NOTICES THAT THE VALVE IS SET TO UNSEAT AT AN EVAPORATOR PRESSURE OF 15 PSI, THE CORRESPONDING SET PRESSURE IN INCHES HG IS

FLOODED EVAPORATORS HAVE HIGH HEAT TRANSFER PER SQUARE FOOT, WHAT MAY BE A DISADVANTAGE?

THE METERING DEVICE USED IN A CONDENSER IS A HIGH SIDE FLOAT, THIS DEVICE WILL:

REGARDING THE PUMP BELOW ELEMENTS A, B, C, D, AND E CORRESPOND TO THE FOLLOWING:

AN OPERATOR CONFIRMS THAT A CHILLER WATER PUMP IN A REFRIGERATING SYSTEM EMPLOYING R-123 IS CAVITATING, OF THE FOLLOWING, THE MOST LIKELY CAUSE FOR THIS CONDITION IS

WHILE DOING A ROUTINE INSPECTION, THE RMO NOTICED THE BULB OF THE TEV ON THE FLOOR, THE OPERATOR SHOULD ATTACH THE BULB AT:

IF YOU HAVE 62 PSI AT 35°F AND 70 PSI AT 45°F, WHAT WOULD 38°F BE?

WHEN A COMPRESSOR IS SAID TO HAVE A SAFETY HEAD THIS MEANS