# Refrigerant Machine Operator Test #3

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| By Catherine Halcomb
Catherine Halcomb
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A refrigerant machine operator is an important person for the transportation of items that need a specified degree of temperature. Are you one of them or just interested? If so, take up the test and all the best.

• 1.

### LIQUID LEVEL GAUGES (EXCEPT BULL'S EYE TYPE) SHALL HAVE SHUT OFF VALVES:

• A.

MANUAL ONLY

• B.

AUTOMATIC ONLY

• C.

VALVES NOT NEEDED

• D.

MANUAL AND AUTOMATIC

D. MANUAL AND AUTOMATIC
Explanation
Liquid level gauges (except bull's eye type) should have shut off valves that can be operated manually and automatically. This means that the shut off valves can be closed manually by an operator and can also be closed automatically in case of any emergency or abnormal conditions. Having both manual and automatic shut off valves ensures that the liquid level can be controlled and the flow can be stopped promptly when required, providing safety and control in the operation of the liquid level gauges.

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• 2.

### CONVERT 20 PSIG TO Hg ABSOLUTE

• A.

30

• B.

70

• C.

80

• D.

90

B. 70
Explanation
To convert PSIG to Hg absolute, we need to use the conversion factor of 1 PSIG = 2.036 Hg absolute. Therefore, to convert 20 PSIG to Hg absolute, we multiply 20 by 2.036, which gives us 40.72 Hg absolute. However, since the answer choices are limited to 30, 70, 80, and 90, the closest value to 40.72 is 70. Hence, the correct answer is 70.

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• 3.

### WHY CAN'T YOU USE A FLARE FITTING 3/4" OR LARGER?

• A.

CAN'T FLARE THAT LARGE

• B.

CAN'T TIGHTEN TO GET A GOOD SEAL

• C.

AGAINST THE LAW

• D.

EASIER TO SWEAT

B. CAN'T TIGHTEN TO GET A GOOD SEAL
Explanation
A flare fitting that is 3/4" or larger cannot be used because it cannot be tightened enough to create a good seal. Flare fittings rely on the compression of the flare against the fitting to create a tight seal, and larger flare fittings may not be able to achieve this level of compression. Therefore, it is easier and more effective to use a different method, such as sweating or soldering, for larger fittings.

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• 4.

### FOR SYSTEMS CONTAINING 50 LBS OF REFRIGERANT, STOP VALVES ARE REQUIRED:

• A.

AT INLET OF EACH COMPRESSOR

• B.

• C.

BEFORE AND AFTER SIGHT GLASS

• D.

NOT REQUIRED

A. AT INLET OF EACH COMPRESSOR
Explanation
Stop valves are required at the inlet of each compressor in systems containing 50 lbs of refrigerant. This is necessary to control the flow of refrigerant into the compressor and to isolate the compressor for maintenance or repair purposes. The stop valve allows for easy shutdown and isolation of the compressor without affecting the rest of the system.

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• 5.

### THE AMOUNT OF VENTILATION FOR REFRIGERANT REMOVAL PURPOSES IN A MACHINE ROOM SHALL BE SIZED ACCORDING TO:

• A.

TOTAL AMOUNT OF REFRIGERANTS IN UNITS

• B.

AMOUNT OF THE MOST FLAMMABLE REFRIGERANT

• C.

AMOUNT OF REFRIGERANT IN LARGEST MACHINE

• D.

TOTAL AMOUNT OF REFRIGERANT IN UNITS AND STORED IN MACHINE ROOM

C. AMOUNT OF REFRIGERANT IN LARGEST MACHINE
Explanation
The amount of ventilation for refrigerant removal purposes in a machine room should be sized according to the amount of refrigerant in the largest machine. This is because the largest machine would likely contain the highest amount of refrigerant, which would require more ventilation to safely remove it from the machine room.

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• 6.

### THE OUTLET FROM A FAN OR AIR DUCT USED TO VENTILATE REFRIGERANTS MUST BE AT LEAST _____ FEET FROM ANY AIR INTAKE OR EXHAUST OR ANY OPENINGS IN AN ADJOINING BUILDING

• A.

5

• B.

10

• C.

20

• D.

50

C. 20
Explanation
The outlet from a fan or air duct used to ventilate refrigerants must be at least 20 feet from any air intake or exhaust or any openings in an adjoining building. This distance is necessary to ensure that the refrigerants are properly vented and do not contaminate the air supply or exhaust systems of the building or neighboring buildings. A greater distance helps to prevent any potential health hazards or damage to the ventilation systems.

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• 7.

### YOU ARE A RMO AND YOU WANT TO WORK ON THE MACHINES PRESSURE RELIEF VALVE ON A DUAL PRESSURE RELIEF VALVE SYSTEM.  WHAT VALVE WOULD YOU INSTALL TO WORK ON ONE PRESSURE RELIEF VALVE WHILE ALLOWING THE OTHER ONE TO OPERATE IN THE SYSTEM?

• A.

GATE VALVE

• B.

BUTTERFLY VALVE OR PLUG VALVE

• C.

TWO WAY VALVE

• D.

THREE WAY VALVE

D. THREE WAY VALVE
Explanation
A three-way valve would be the appropriate choice in this situation because it allows the RMO to work on one pressure relief valve while still allowing the other one to operate in the system. The three-way valve has three ports, which can be used to divert the flow of fluid. By positioning the valve correctly, the RMO can isolate one pressure relief valve from the system while still allowing the other one to function properly. This provides a safe and efficient way to work on the machines' pressure relief valve without disrupting the overall operation of the system.

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• 8.

### A WATER REGULATING VALVE IS CONNECTED TO THE OUTLET OF THE CONDENSER.  WHAT IS THIS VALVE DESIGNED TO DO?

• A.

MAINTAIN A CONDENSER PRESSURE WITHIN PRESET LIMITS

• B.

MAINTAIN A CONSTANT WATER PRESSURE

• C.

MAINTAIN A CONSTANT WATER TEMPERATURE

• D.

MAINTAIN A CONSTANT CONDENSER PRESSURE

D. MAINTAIN A CONSTANT CONDENSER PRESSURE
Explanation
The water regulating valve is designed to maintain a constant condenser pressure. This means that it controls the flow of water into the condenser to ensure that the pressure remains within a predetermined range. By regulating the water flow, the valve helps to maintain optimal operating conditions for the condenser, which is crucial for the efficient functioning of the system.

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• 9.

### YOU ARE AN RMO AND YOU START THE MACHINE AND THE MACHINE DOESN'T START.  YOUR FUSES, CIRCUIT BREAKERS AND ELECTRICAL COMPONENTS ARE ALL GOOD.  WHAT WOULD YOU CHECK NEXT?

• A.

SIGHTGLASS

• B.

THERMOSTAT

• C.

LOW PRESSURE CUT OUT, PRESSURE SWITCH

• D.

REFRIGERANT CHARGE

C. LOW PRESSURE CUT OUT, PRESSURE SWITCH
Explanation
If the fuses, circuit breakers, and electrical components are all good, the next thing to check would be the low pressure cut out and pressure switch. These components are responsible for monitoring the pressure in the system and can shut off the machine if the pressure is too low. If these components are faulty or not functioning properly, they could be preventing the machine from starting. Therefore, checking the low pressure cut out and pressure switch would be the logical next step in troubleshooting the issue.

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• 10.

### WHAT IS A SUPERHEATED VAPOR?

• A.

VERY HIGH TEMPERATURE GAS MIXED WITH LIQUID

• B.

DRY VAPOR

• C.

DRY VAPOR AT ITS BOILING POINT

• D.

DRY VAPOR ABOVE ITS BOILING POINT

D. DRY VAPOR ABOVE ITS BOILING POINT
Explanation
A superheated vapor refers to a vapor that is in a gaseous state and is at a temperature higher than its boiling point. In other words, it is a dry vapor that has been heated beyond the point where it would normally condense into a liquid. This can occur when heat is added to a vapor without increasing its pressure, causing the temperature to rise above the boiling point.

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• 11.

### HOW DOES A SOLENOID VALVE WORK?

• A.

OPEN A PLUNGER AND ALLOW REFRIGERANT IN

• B.

OPEN SPRING VALVE AND ALLOW REFRIGERANT IN

• C.

MANUALLY OPEN AND ALLOW REFRIGERANT IN

• D.

MANUALLY CLOSE AND PREVENT REFRIGERANT IN

A. OPEN A PLUNGER AND ALLOW REFRIGERANT IN
Explanation
A solenoid valve works by opening a plunger and allowing refrigerant to flow in. When an electrical current is applied to the solenoid coil, it creates a magnetic field that pulls the plunger away from the valve seat, opening the passage for refrigerant to enter. This allows for the controlled flow of refrigerant in a system.

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• 12.

### WHEN A THERMOSTATIC EXPANSION VALVE IS OPERATING PROPERLY, THE END OF THE COIL WILL CONTAIN

• A.

SATURATED VAPOR

• B.

SUPERHEATED VAPOR

• C.

LOW TEMPERATURE LIQUID

• D.

HOT VAPOR

B. SUPERHEATED VAPOR
Explanation
When a thermostatic expansion valve is operating properly, the end of the coil will contain superheated vapor. This is because the expansion valve is designed to regulate the flow of refrigerant into the evaporator coil. As the high-pressure liquid refrigerant passes through the expansion valve, it undergoes a phase change and turns into a mixture of saturated liquid and vapor. The saturated liquid further evaporates inside the coil, absorbing heat from the surroundings and becoming superheated vapor. Therefore, the correct answer is superheated vapor.

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• 13.

### A COMPRESSOR THAT USES A SHAFT WITH A MECHANICAL SEAL, WHAT IS THE VALVE PLATE MADE OF?

• A.

METAL/CARBON

• B.

PLASTIC

• C.

RUBBER

• D.

SILICON

A. METAL/CARBON
Explanation
The valve plate of a compressor that uses a shaft with a mechanical seal is typically made of metal/carbon. This material combination provides durability and resistance to wear and tear, making it suitable for the high-pressure and high-temperature conditions in a compressor. Metal provides strength and stability, while carbon offers self-lubricating properties and low friction. This combination ensures efficient operation and a longer lifespan for the valve plate.

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• 14.

### ON A VALVE PLATE, WHERE ARE THE SUCTION AND DISCHARGE VALVES LOCATED?

• A.

SUCTION ON TOP, DISCHARGE ON BOTTOM

• B.

SUCTION ON BOTTOM, DISCHARGE ON TOP

• C.

SUCTION AND DISCHARGE ON TOP

• D.

SUCTION AND DISCHARGE ON BOTTOM

B. SUCTION ON BOTTOM, DISCHARGE ON TOP
Explanation
On a valve plate, the suction and discharge valves are located with the suction valve on the bottom and the discharge valve on the top.

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• 15.

### WHAT CONTROLS A SOLENOID VALVE ON MOTOR?

• A.

WATTS

• B.

VOLTS

• C.

HORSE POWER

• D.

AMPS

B. VOLTS
Explanation
Volts control a solenoid valve on a motor. Solenoid valves are electromechanical devices that use an electrical current to control the flow of fluid or gas. The voltage applied to the solenoid coil determines the strength of the magnetic field generated, which in turn controls the opening and closing of the valve. By adjusting the voltage, the speed and force of the valve can be regulated to suit the specific requirements of the motor. Therefore, volts play a crucial role in controlling the operation of a solenoid valve on a motor.

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• 16.

### WHY IS GLYCOL A BETTER BRINE THAN SODIUM CHLORIDE?

• A.

MORE CONDUCTIVE

• B.

COST LESS

• C.

NO CORROSION

• D.

HIGHER FREEZING POINT

C. NO CORROSION
Explanation
Glycol is a better brine than sodium chloride because it does not cause corrosion. This means that when glycol is used as a brine, it does not damage or deteriorate the equipment or pipes it comes into contact with. In contrast, sodium chloride can cause corrosion over time, leading to potential damage and maintenance costs. Therefore, glycol is a preferable option as a brine due to its non-corrosive properties.

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• 17.

### WHAT DOES A FILTER DRIER DO?

• A.

REMOVES PARTICLES

• B.

REMOVES MOISTURE

• C.

REMOVES ACID

• D.

ALL OF THE ABOVE

D. ALL OF THE ABOVE
Explanation
A filter drier is a device used in HVAC systems to remove particles, moisture, and acid from the refrigerant. It helps to maintain the cleanliness and efficiency of the system by preventing clogs, corrosion, and damage caused by these contaminants. By removing particles, moisture, and acid, the filter drier ensures that the refrigerant circulates properly and that the system operates effectively. Therefore, the correct answer is "ALL OF THE ABOVE."

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• 18.

### HOW DOES A RECIPROCATING COMPRESSOR VARY CAPACITY?

• A.

• B.

HOT GAS BYPASS

• C.

MOTOR SPEED VARIATIONS

• D.

ALL OF THE ABOVE

D. ALL OF THE ABOVE
Explanation
All of the above options - cylinder unloaders, hot gas bypass, and motor speed variations - can vary the capacity of a reciprocating compressor. Cylinder unloaders allow for the selective unloading of cylinders, reducing the capacity of the compressor. Hot gas bypass allows for the diversion of hot gas from the discharge side to the suction side, regulating the capacity. Motor speed variations can control the speed of the compressor, thereby adjusting the capacity.

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• 19.

• A.

PRESSURE RELIEF VALVE INSIDE THE COMPRESSOR

• B.

PRESSURE RELIEF VALVE AT TOP OF THE HEAD

• C.

VALVE PLATE BEING HELD DOWN BY A SPRING

• D.

HIGH SIDE PRESSURE IN SYSTEM BELOW DESIGN PRESSURE

C. VALVE PLATE BEING HELD DOWN BY A SPRING
Explanation
A safety head refers to a valve plate that is held down by a spring. This valve plate acts as a safety mechanism in a compressor system. When the pressure inside the compressor reaches a certain level, the spring-loaded valve plate opens to release excess pressure, preventing any potential damage or malfunction. This ensures the safe operation of the compressor and protects it from overpressure situations.

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• 20.

### WHEN WATER TURNS TO ICE, WHAT TAKES PLACE?

• A.

SUPERHEAT

• B.

HEAT OF FUSION

• C.

HEAT OF EVAPORATION

• D.

SUBCOOLING

B. HEAT OF FUSION
Explanation
When water turns to ice, heat energy is released from the water and transferred to the surroundings. This process is known as the heat of fusion. The heat of fusion is the amount of energy required to change a substance from a liquid to a solid state at its melting point. In the case of water, this is the energy released when it freezes and forms ice.

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• 21.

### What is the primary function of the receiver in a refrigeration system?

• A.

To absorb heat from the refrigerant

• B.

To store the refrigerant after condensation

• C.

To increase the pressure of the refrigerant

• D.

To maintain the refrigerant at a constant temperature

B. To store the refrigerant after condensation
Explanation
The receiver in a refrigeration system acts as a storage tank for the refrigerant after it has condensed from a gas to a liquid in the condenser. This allows the system to manage fluctuations in cooling demand and provides a reservoir of liquid refrigerant ready for the evaporative phase of the cycle. This component does not directly absorb heat, increase pressure, or regulate temperature; rather, it ensures that a sufficient quantity of liquid refrigerant is available for continuous system operation.

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• 22.

### IF REFRIGERANT OIL IS MEASURED TO HAVE A VISCOSITY AND THE VISCOSITY NUMBER IS LOW, WHAT DOES THAT MEAN?

• A.

DOESN'T FLOW

• B.

FLOWS EASILY, SMOOTHLY

• C.

FLOW IS SLOW

• D.

RESTRICTED FLOW

B. FLOWS EASILY, SMOOTHLY
Explanation
If the refrigerant oil is measured to have a low viscosity number, it means that the oil flows easily and smoothly. Viscosity is a measure of a fluid's resistance to flow, so a low viscosity indicates that the oil has a thin consistency and can move easily. This is beneficial for the refrigeration system as it allows for smooth and efficient circulation of the oil, ensuring proper lubrication and cooling.

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• 23.

### IF YOU NEED TO ADD ANOTHER PUMP ONLINE, HOW DO YOU DO IT?

• A.

OPEN SUCTION SIDE VALVE AND PUT DISCHARGE IN THE THROTTLE POSITION

• B.

OPEN SUCTION, CLOSE DISCHARGE

• C.

CLOSE SUCTION, OPEN DISCHARGE

• D.

OPEN SUCTION AND SLOWLY FULLY OPEN DISCHARGE

A. OPEN SUCTION SIDE VALVE AND PUT DISCHARGE IN THE THROTTLE POSITION
• 24.

### THE AUTOMATIC EXPANSION VALVE (AEV) IS USED INSTEAD OF A TEV.  IT MAINTAINS A CONSTANT PRESSURE ON THE EVAPORATOR. ANOTHER FUNCTION IT MAY HAVE IS:

• A.

• B.

ALLOWS REFRIGERANT ON RISE IN PRESSURE

• C.

NEEDS TEMPERATURE CONTROL TO PROTECT EVAPORATOR FROM FREEZING UP FROM COLD WATER

• D.

ON WATER TYPE EVAPORATOR, FREEZING WILL NOT OCCUR

D. ON WATER TYPE EVAPORATOR, FREEZING WILL NOT OCCUR
Explanation
The explanation for the given correct answer is that the Automatic Expansion Valve (AEV) is specifically designed for water type evaporators, where freezing of the evaporator will not occur. This means that the AEV does not require temperature control to protect the evaporator from freezing up due to cold water. The AEV maintains a constant pressure on the evaporator, ensuring efficient operation even with variable loads. Additionally, the AEV allows the refrigerant to rise in pressure as needed, further optimizing its performance.

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• 25.

### THE PRESSURE OF WATER GOING THROUGH A SHELL AND TUBE CONDENSER IS PROPORTIONAL TO THE SQUARE OF ITS VELOCITY.  IF ITS VELOCITY ORIGINALLY WAS 40 AND IT'S ORIGINAL PRESSURE WAS HALVED, WHAT WOULD THE VELOCITY BE?

• A.

40

• B.

30

• C.

20

• D.

10

D. 10
Explanation
The pressure of water going through a shell and tube condenser is proportional to the square of its velocity. If the original velocity was 40 and the original pressure was halved, the new velocity can be calculated by taking the square root of the original velocity and multiplying it by the square root of the original pressure. In this case, the square root of 40 is 6.32, and the square root of 0.5 (halved pressure) is 0.71. Multiplying these two values together gives a new velocity of approximately 4.49, which is closest to 10. Therefore, the new velocity would be 10.

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• 26.

### IF 10 BTUs IS TRANSFERRED TO 10 LBS. OF WATER, THE INCREASE IN TEMPERATURE IS CLOSEST TO:

• A.

10Â°F

• B.

10Â°C

• C.

1Â°F

• D.

1Â°C

C. 1Â°F
Explanation
When 10 BTUs of heat is transferred to 10 lbs. of water, the increase in temperature is closest to 1Â°F. This is because the specific heat capacity of water is 1 BTU/lbÂ°F, which means that it takes 1 BTU of heat to raise the temperature of 1 lb. of water by 1Â°F. Therefore, when 10 BTUs of heat is transferred to 10 lbs. of water, the temperature will increase by 1Â°F.

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• 27.

### WHAT IS THE ORDER OF COMPONENTS ON THE LIQUID LINE OF A RECIPROCATING SYSTEM FROM THE KING VALVE?

• A.

FILTER DRIER, SOLENOID VALVE, SIGHT GLASS, TEV TO EVAPORATOR

• B.

SOLENOID VALVE, FILTER DRIER, SIGHT GLASS, TEV TO EVAPORATOR

• C.

SIGHT GLASS, SOLENOID VALVE, FILTER DRIER, TEV TO EVAPORATOR

• D.

TEV, SIGHT GLASS, SOLENOID VALVE, FILTER DRIER TO EVAPORATOR

A. FILTER DRIER, SOLENOID VALVE, SIGHT GLASS, TEV TO EVAPORATOR
Explanation
The correct order of components on the liquid line of a reciprocating system from the king valve is filter drier, solenoid valve, sight glass, TEV to evaporator. This order ensures that the refrigerant passes through the filter drier first to remove any contaminants, then through the solenoid valve to control the flow of refrigerant, followed by the sight glass to provide a visual indication of the refrigerant's condition, and finally through the TEV (Thermal Expansion Valve) to regulate the flow of refrigerant into the evaporator.

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• 28.

### THE UNIT USED TO MEASURE THE AMOUNT OF ELECTRONS FLOWING PAST A CERTAIN POINT IN AN ELECTRICAL CIRCUIT IS CALLED:

• A.

OHM

• B.

AMPERE

• C.

VOLT

• D.

WATT

• E.

NONE OF THE ABOVE

B. AMPERE
Explanation
The unit used to measure the amount of electrons flowing past a certain point in an electrical circuit is called Ampere. Ampere is the SI unit of electric current and is defined as the rate of flow of electric charge. It represents the number of electrons passing through a point in a circuit per second. Ohm is the unit of electrical resistance, Volt is the unit of electric potential difference, and Watt is the unit of power. None of the above options accurately measure the flow of electrons in a circuit.

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• 29.

### BEFORE USING A VOLTMETER, THE TECHNICIAN SHOULD ALWAYS:

• A.

• B.

TOUCH THE TWO LEADS TOGETHER TO ENSURE CONTINUITY

• C.

SET THE RANGE SELECTOR TO A SETTING HIGHER THAN THE VOLTAGE EXPECTED TO BE READ

• D.

TURN THE POWER OFF

• E.

NONE OF THE ABOVE

C. SET THE RANGE SELECTOR TO A SETTING HIGHER THAN THE VOLTAGE EXPECTED TO BE READ
Explanation
The technician should always set the range selector to a setting higher than the voltage expected to be read before using a voltmeter. This is because if the range selector is set too low, it may not be able to accurately measure the voltage and could potentially damage the voltmeter. By setting the range selector higher, the technician ensures that the voltmeter can handle the voltage being measured and provides a more accurate reading.

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• 30.

### AS AN RMO YOU ENTER A SYSTEM OF A RECIPROCATING REFRIGERATION UNIT.  THIS SYSTEM HAS A 150 LB. REFRIGERANT CHARGE, YOU WOULD EXPECT TO FIND STOP VALVES:

• A.

ON THE INLET SUPPLY AND DISCHARGE LINE

• B.

BEFORE AND AFTER LIQUID BULL'S EYE SIGHT GLASS

• C.

ON THE INLET LINE OF THE CONDENSER RECEIVER

• D.

ON THE INLET TO EACH COMPRESSOR

C. ON THE INLET LINE OF THE CONDENSER RECEIVER
Explanation
In a reciprocating refrigeration unit, the condenser receiver is a component that stores the condensed refrigerant before it is sent to the expansion valve. The stop valve on the inlet line of the condenser receiver helps to control the flow of refrigerant into the receiver and allows for maintenance and repairs to be done safely. Therefore, it is expected to find stop valves on the inlet line of the condenser receiver.

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• 31.

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

• A.

A REFRIGERANT FIRE

• B.

REFRIGERANT POISONING

• C.

OXYGEN DEPRIVATION

• D.

ATMOSPHERIC SUPERHEATING

C. OXYGEN DEPRIVATION
Explanation
In the event of a refrigerant escape, regardless of the safety classification of the refrigerant in use, the RMO (Responsible Managing Officer) should be aware of oxygen deprivation. When refrigerant escapes, it can displace the oxygen in the surrounding area, leading to a lack of oxygen for individuals in that space. This can be dangerous and potentially life-threatening if not addressed promptly. Therefore, it is crucial for the RMO to be aware of this risk and take appropriate measures to ensure the safety of all personnel.

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• 32.

### WHEN YOU ARE FINISHED LEAK TESTING WITH NITROGEN AND R-22, THEN THE NEXT STEP WOULD BE:

• A.

VENT REFRIGERANT AND NITROGEN TO OPEN AIR

• B.

REMOVE REFRIGERANT AND NITROGEN AT RECOVERY MACHINE

• C.

• D.

ADD REFRIGERANT IF NEEDED AND PUT SYSTEM BACK ONLINE

A. VENT REFRIGERANT AND NITROGEN TO OPEN AIR
• 33.

### WHEN OIL LEAVES THE SUMP IN A CENTRIFUGAL REFRIGERATION SYSTEM, WHERE DOES THE OIL GO?

• A.

TRAVELS WITH THE REFRIGERANT TO COOL THE REFRIGERATION SYSTEM

• B.

TRAVELS BACK TO THE OIL SUMP

• C.

IS COMPATIBLE WITH REFRIGERANT AND WILL TRAVEL THROUGH SYSTEM AND RETURN TO THE OIL SUMP

• D.

TRAVELS THROUGH THE SYSTEM AND IS DRAINED OUT OF THE SUMP BY A PETCOCK VALVE

B. TRAVELS BACK TO THE OIL SUMP
Explanation
When oil leaves the sump in a centrifugal refrigeration system, it travels back to the oil sump. This means that the oil circulates within the system and returns to its original location.

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• 34.

### THE TYPE OF REFRIGERANT IN THE FEELER BULB ON A SYSTEM WOULD BE:

• A.

SAME AS REFRIGERANT IN SYSTEM

• B.

HIGHLY FLAMMABLE / HIGHLY TOXIC

• C.

NON FLAMMABLE / NON TOXIC

• D.

WOULD BE DIFFERENT TYPE OF REFRIGERANT THAN THE ONE IN THE SYSTEM

C. NON FLAMMABLE / NON TOXIC
Explanation
The correct answer is "NON FLAMMABLE / NON TOXIC". This means that the refrigerant in the feeler bulb on a system is not flammable and does not pose any toxic risks. This is important because the feeler bulb is a component that senses temperature and pressure changes in the system. Using a non-flammable and non-toxic refrigerant ensures safety and prevents any potential hazards in the system.

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• 35.

### WHAT IS THE PRESSURE OF R-22 AT 41°F?

• A.

38 PSIG

• B.

70 PSIG

• C.

18.5" Hg

• D.

81

B. 70 PSIG
Explanation
The pressure of R-22 at 41Â°F is 70 PSIG. This indicates that the refrigerant R-22 is at a pressure of 70 pounds per square inch gauge at a temperature of 41Â°F.

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• 36.

### ASIDE FROM VENTING REFRIGERANT FROM YOUR HOSE CONNECTIONS, THE ONLY OTHER TIME YOU MAY DISCHARGE REFRIGERANT WOULD BE?

• A.

WHEN A FIRE DEPT ENGINEER IS PRESENT

• B.

NEVER

• C.

AFTER THE FIRE DEPT ENGINEER LEAVES THE ROOM

• D.

TO CHECK IF THERE IS REFRIGERANT IN THE SYSTEM

B. NEVER
Explanation
Discharging refrigerant should never be done unless it is necessary for maintenance or repair purposes. It is important to follow proper procedures and regulations when handling refrigerants to prevent harm to the environment and ensure the safe operation of the system. Discharging refrigerant without a valid reason can lead to environmental pollution and is generally considered illegal. Therefore, the correct answer is "NEVER".

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• 37.

### AFTER THE COMPRESSOR YOU HAVE THE OIL SEPARATOR, WHICH:

• A.

IN GENERAL RETURNS THE OIL TO THE CRANKCASE

• B.

FILTERS THE OIL AND RETURNS THE OIL TO THE CRANKCASE

• C.

REMOVES THE WATER FROM THE OIL

• D.

DISTRIBUTES OIL TO THE EVAPORATOR

A. IN GENERAL RETURNS THE OIL TO THE CRANKCASE
Explanation
The oil separator, after the compressor, is responsible for separating the oil from the compressed air. It then generally returns the oil back to the crankcase of the system. This is important as it ensures that the oil is properly circulated and lubricates the moving parts of the compressor. By returning the oil to the crankcase, it helps maintain the efficiency and performance of the compressor.

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• 38.

### AN OPEN TYPE COMPRESSOR IS KEEPING THE REFRIGERANT FROM ESCAPING BY TIGHTENING A SEAL MADE OF:

• A.

RUBBER

• B.

• C.

CARBON AND METAL

• D.

FORTIFIED PLASTIC

C. CARBON AND METAL
Explanation
An open type compressor is keeping the refrigerant from escaping by tightening a seal made of carbon and metal. Carbon and metal are both strong materials that can withstand the pressure and temperature fluctuations in a compressor. They provide a tight and secure seal to prevent any leakage of the refrigerant.

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• 39.

### HOW MANY BTUs ARE ABSORBED IN 5 TONS OF ICE?

• A.

188,000

• B.

2,200,000

• C.

1,440,000

• D.

NONE

C. 1,440,000
Explanation
In this question, the correct answer is 1,440,000. BTU is a unit of energy, and it stands for British Thermal Unit. The question asks how many BTUs are absorbed in 5 tons of ice. Ice has a specific heat capacity of 0.5 BTU/lbÂ°F, and it takes 144 BTUs to melt 1 lb of ice. Since there are 2,000 lbs in a ton, 5 tons of ice would be 10,000 lbs. Therefore, to calculate the total BTUs absorbed, we multiply the weight (10,000 lbs) by the heat capacity (0.5 BTU/lbÂ°F) and the melting point (144 BTUs), which gives us 1,440,000 BTUs.

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• 40.

### WHAT ARE THE RECOVERY REQUIREMENTS FOR LOW PRESSURE APPLIANCES

• A.

25" Hg

• B.

0 PSI

• C.

10" Hg

• D.

5" Hg

A. 25" Hg
Explanation
The recovery requirements for low-pressure appliances is 25" Hg. This means that the pressure should be reduced to 25 inches of mercury during the recovery process. This is important to ensure the safe and efficient removal of refrigerants from the appliance. By reducing the pressure to 25" Hg, the refrigerant can be effectively recovered without causing any damage to the appliance or posing any safety risks.

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• 41.

### IF YOU ARE USING A RECOVERY MACHINE TO RECOVER REFRIGERANT FROM THE SYSTEM WITHOUT USING THE SYSTEM COMPRESSOR, WHAT KIND OF RECOVERY MACHINE IS THAT?

• A.

SELF CONTAINED

• B.

SELF DEPENDENT

• C.

CENTRIFUGAL RECOVERY MACHINE

• D.

NONE OF THE ABOVE

A. SELF CONTAINED
Explanation
A self-contained recovery machine is used to recover refrigerant from a system without using the system compressor. This type of recovery machine is designed to operate independently and does not rely on the system's compressor to remove the refrigerant. It is a standalone unit that is capable of recovering refrigerant efficiently and effectively.

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• 42.

### WHEN IS A CENTRIFUGAL WATER PUMP CONSIDERED A "LIFT PUMP"?

• A.

WHEN THE SUCTION INLET OF THE WATER SOURCE IS BELOW THE PUMP LEVEL

• B.

WHEN THE DISCHARGE IS 120' ABOVE

• C.

WHEN THE WATER IS LIFTED BY PUMP

• D.

WHEN THE PUMP WEIGHS LESS THAN 50 LBS.

A. WHEN THE SUCTION INLET OF THE WATER SOURCE IS BELOW THE PUMP LEVEL
Explanation
A centrifugal water pump is considered a "lift pump" when the suction inlet of the water source is below the pump level. This means that the pump is able to lift water from a lower source to a higher discharge point. In this scenario, the pump is primarily responsible for creating the necessary suction force to draw water from the lower source and push it to a higher point.

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• 43.

### WHERE DO NON-CONDENSABLE VAPORS AND MOISTURE COLLECT?

• A.

LIQUID LINE

• B.

CONDENSER

• C.

EVAPORATOR

• D.

FILTER DRIER

B. CONDENSER
Explanation
Non-condensable vapors and moisture collect in the condenser. The condenser is a component of a refrigeration system where the high-temperature refrigerant vapor is cooled and condensed into a liquid. During this process, any non-condensable vapors and moisture present in the refrigerant will also be condensed and collected in the condenser.

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• 44.

### AFTER LEAK DETECTING WITH MOISTURE OF NITROGEN AND A TRACE OF R-22, THE RMO:

• A.

HAS TO RECOVER ONLY THE R-22

• B.

CAN VENT THE MIXTURE TO THE ATMOSPHERE

• C.

RECOVER BOTH INTO THE SAME CONTAINER

• D.

RECOVER BOTH, BUT IN SEPARATE CYLINDERS

B. CAN VENT THE MIXTURE TO THE ATMOSPHERE
Explanation
The correct answer is "CAN VENT THE MIXTURE TO THE ATMOSPHERE." This means that after leak detecting with moisture of nitrogen and a trace of R-22, the RMO is allowed to release the mixture of nitrogen and R-22 into the atmosphere. This suggests that the mixture is not considered harmful or hazardous, and it is acceptable to vent it into the surrounding environment.

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• 45.

### THE RMO WANTS TO GET A TEMPERATURE READING FROM THE SUCTION LINE, BUT THERE ARE NO GAUGES:

• A.

THE RMO CAN TOUCH THE LINE AND USE HIS EXPERIENCE TO ESTIMATE WHAT THE TEMPERATURE IS

• B.

BUY A THERMOMETER AND STICK IT ON THE SUCTION LINE WITH PUTTY

• C.

GET TWO THERMOMETERS AND GET THE AVERAGE READINGS

• D.

TOUCH THE THERMOMETER ON THE SUCTION LINE AND GET A READING

B. BUY A THERMOMETER AND STICK IT ON THE SUCTION LINE WITH PUTTY
Explanation
The best explanation for the given correct answer is that buying a thermometer and sticking it on the suction line with putty is the most accurate and reliable method to get a temperature reading. This method ensures that the thermometer is directly in contact with the suction line, providing an accurate measurement. Touching the line and using experience to estimate the temperature may not be as precise, and getting average readings from two thermometers may introduce additional variability.

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• 46.

### HOW DO YOU CONTROL CAPACITY OF A CENTRIFUGAL COMPRESSOR WITH VARIABLE GUIDE VANES?

• A.

INCREASE SUB-COOLING

• B.

INCREASE THE SPEED OF THE MOTOR

• C.

VARY THE PASSAGES OF THE VANES

• D.

PISTON VALVE CLEARANCE

C. VARY THE PASSAGES OF THE VANES
Explanation
By varying the passages of the vanes in a centrifugal compressor with variable guide vanes, the capacity of the compressor can be controlled. This means that by adjusting the angle or position of the guide vanes, the flow of the gas or fluid through the compressor can be regulated. This allows for flexibility in controlling the amount of compression and therefore the capacity of the compressor. By changing the passages of the vanes, the compressor can be adjusted to meet the specific requirements of the system it is operating in.

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• 47.

### A RECIPROCATING COMPRESSOR SHAFT SEAL IS MADE UP OF:

• A.

PLASTIC

• B.

RUBBER

• C.

GRAPHITE FIBER HEMP

• D.

METAL

D. METAL
Explanation
A reciprocating compressor shaft seal is made up of metal because metal seals are known for their durability, strength, and ability to withstand high pressures and temperatures. Metal seals also provide a tight and reliable seal, preventing any leakage of the compressed gas. Additionally, metal seals are resistant to wear and tear, making them suitable for the reciprocating motion of the compressor shaft.

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• 48.

### WHAT IS THE MINIMUM HEIGHT LEVEL INSIDE THE MACHINERY ROOM EXHAUST?

• A.

LESS THAN 5'

• B.

MORE THAN 5'

• C.

25'

• D.

50'

A. LESS THAN 5'
Explanation
The minimum height level inside the machinery room exhaust is less than 5'. This means that the height of the machinery room exhaust is below 5 feet.

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• 49.

### CENTRIFUGAL COMPRESSORS USE WHAT KIND OF REFRIGERANT?

• A.

CFCs

• B.

HIGH PRESSURE REFRIGERANT

• C.

LOW PRESSURE REFRIGERANT

• D.

ALL THE ABOVE

D. ALL THE ABOVE
Explanation
Centrifugal compressors can use all of the above refrigerants, including CFCs, high-pressure refrigerants, and low-pressure refrigerants. The choice of refrigerant depends on various factors such as the specific application, desired performance, environmental regulations, and safety considerations.

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• 50.

### TO PREVENT AGAINST STRUCTURAL COLLAPSE IN PIPE WORK, WHEN INSTALLING BENDED COPPER TUBING:

• A.

USE ANNEALED COPPER

• B.

USE A SPRING BENDER

• C.

• D.

USE BRAZED ELBOWS

Explanation
When installing bended copper tubing, using a large radius helps prevent structural collapse in the pipe work. A large radius allows for a smoother bend, reducing the stress and strain on the tubing. This helps to maintain the integrity of the tubing and prevents it from collapsing under pressure. Using a smaller radius could cause the tubing to kink or deform, leading to potential failure or leaks in the system. Therefore, using a large radius is the best choice to prevent structural collapse in pipe work.

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

• Current Version
• Apr 17, 2024
Quiz Edited by
ProProfs Editorial Team
• Feb 10, 2014
Quiz Created by
Catherine Halcomb

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