Archive for February 2017

What is the function of the concentrator (generator)?

What is the function of the concentrator (generator)?




a) To cool the refrigerant vapour
b) To increase the absorbency potential of used Lithium Bromide
c) To speed up the evaporation of the refrigerant
d) To cool the concentrated absorbent
e) To exchange heat between the high temperature refrigerant vapour and the atmosphere







Answer: B

In comparing absorption and compression refrigeration systems, which of the following comparisons is true?

In comparing absorption and compression refrigeration systems, which of the following comparisons is true?




a. Slugs of liquid carried over from the evaporator do not damage the compression system but can ruin an absorption system
b. Absorption systems require less space than compression systems
c. Cooling water requirements are larger for an absorption system than for a compression system
d. More equipment and piping are required for a compression system
e. Pumps in absorption systems require more electrical power








Answer: C

The absorber in the lithium bromide refrigeration system is equipped with a pump

The absorber in the lithium bromide refrigeration system is equipped with a pump



a. To force water into a finely divided state
b. To decrease contact between absorbent and refrigerant
c. To decrease the refrigerant evaporation point
d. To speed the absorption of water vapour
e. To keep the cycle pressure constant







Answer: D

In an absorption refrigeration system, the compressor used in a compression refrigeration system is eliminated. Instead, the compressor's functions are performed by the:

In an absorption refrigeration system, the compressor used in a compression refrigeration system is eliminated. Instead, the compressor's functions are performed by the:




a. condenser, expansion valve, and the receiver
b. evaporator, absorber and generator
c. generator pump, evaporator pump, and the absorber pump
d. absorber, generator, and the generator pump
e. evaporator, absorber, and the generator







Answer: D

Which of the following statements about Lithium bromide absorption refrigeration systems is false?

Which of the following statements about Lithium bromide absorption refrigeration systems is false?




a. Lithium bromide solution has the ability to absorb water vapour readily
b. The system efficiency is increased by forcing water through a spray header
c. Evacuating the system lowers the boiling point of water
d. As water vapour is absorbed by lithium bromide, the vacuum in the evaporator decreases
e. The operating cycle in the system is continuous








Answer: D

Most absorption refrigeration systems are put in place where there is cheap excess or waste heat available. What is this heat primarily used for?

Most absorption refrigeration systems are put in place where there is cheap excess or waste heat available. What is this heat primarily used for?




a. To pressurize the system
b. To evaporate the water out of the weak Lithium Bromide
c. To decrease the evaporation point of the refrigerant
d. To maintain a minimum load on the system, during periods of low cooling demand
e. To maintain the continuous vacuum








Answer: B

In the Lithium Bromide refrigeration system, what is the function of the concentrator (generator)?

In the Lithium Bromide refrigeration system, what is the function of the concentrator (generator)?





a. To exchange heat between the high temperature refrigerant vapour and the atmosphere
b. To increase the absorbency potential of used absorbent
c. To speed up the evaporation of the refrigerant
d. To cool the concentrated absorbent
e. To cool the refrigerant vapour






Answer: B

Which of the following steps is not a step in the startup of a reciprocating or rotary compressor refrigerating system?

Which of the following steps is not a step in the startup of a reciprocating or rotary compressor refrigerating system?




a) Check oil level in the compressor, it should be at or above the centre of the sight glass.
b) Check the setting of high and low pressure cutout switches.
c) Open all shutoff valves in the system except bypass valves used elsewhere in the system.
d) Valves in lines connecting suction gages should be closed.
e) Check oil level in the compressor; it should be below the centre of the sight glass.







Answer: D

When a chiller has stopped due to low water temperature, and the chilled water temperature subsequently rises approximately 5-6°C above the chilled water temperature set point, the:

When a chiller has stopped due to low water temperature, and the chilled water temperature subsequently rises approximately 5-6°C above the chilled water temperature set point, the:





a. Compressor will restart
b. Compressor will require a manual reset
c. Cooling tower fan will restart
d. Cooling tower fan will shut down
e. Condenser pump will restart





Answer: A

To avoid liquid slugging in a direct expansion evaporator after shutting down a reciprocating or rotary compressor refrigerating system which of the following measures needs to be taken?

To avoid liquid slugging in a direct expansion evaporator after shutting down a reciprocating or rotary compressor refrigerating system which of the following measures needs to be taken?




a. Pump down the evaporator
b. Drain the liquid from the evaporator into the high-side
c. Discharge the condenser refrigerant into the evaporator
d. Open all the suction valves on the connecting condenser line
e. Fill the evaporator with refrigerant vapour







Answer: A

A system of regularly scheduled inspections and lubrications along with the adjustments, minor parts replacement and minor repairs necessary to keep the refrigerating plant and equipment in good operating condition is defined as what:

A system of regularly scheduled inspections and lubrications along with the adjustments, minor parts replacement and minor repairs necessary to keep the refrigerating plant and equipment in good operating condition is defined as what:




a. Preventive maintenance
b. Repair maintenance
c. Routing operation
d. Regular maintenance
e. Troubleshooting








Answer: A

Which of the following steps is not part of the start-up procedure of a centrifugal compressor refrigerating system?

Which of the following steps is not part of the start-up procedure of a centrifugal compressor refrigerating system?





a. Operate the oil pump for at least ten (10) minutes before starting the compressor
b. Open the stop valves in the chilled water system
c. Open the main circuit breakers
d. Open the makeup water valve
e. Check the refrigerant levels







Answer: C

An entire centrifugal compressor refrigerating system, including the auxiliary equipment, can be stopped by simply pressing a stop button, unless

An entire centrifugal compressor refrigerating system, including the auxiliary equipment, can be stopped by simply pressing a stop button, unless




a. The system is automatically controlled
b. The system's auxiliary equipment is not electrically interlocked
c. The system's auxiliary equipment can be stopped simultaneously
d. The compressor can be shut down at the same time as the other equipment
e. There is a cooling demand that must be satisfied







Answer: B

Over charging the system with refrigerant will create:

Over charging the system with refrigerant will create:





a. The formation of bubbles in the sight glass
b. A high discharge condition
c. A low-pressure suction condition
d. The formation of frost at the compressor inlet
e. A low oil pressure condition







Answer: B

Which of the following steps is not part of a start-up of a reciprocating or rotary compressor refrigerating system?

Which of the following steps is not part of a start-up of a reciprocating or rotary compressor refrigerating system?




a. Check for proper oil level in the compressor
b. All shutoff valves in the system should be open
c. Open shutoff valves in the cooling water supply and return lines of water-cooled condensers
d. Valves in pressure page piping should be closed
e. Check the setting of high and low pressure cut out switches







Answer: D

If the chilled water temperature drops approximately 2.5-3°C below the chilled water temperature set point, the chilled water low temperature cut out will:

If the chilled water temperature drops approximately 2.5-3°C below the chilled water temperature set point, the chilled water low temperature cut out will:



a. Start the compressor
b. Shut down the compressor
c. Stop the chilled water pumps
d. Shut down the cooling tower fan
e. Start the condenser pump







Answer: B

The chilled water flow switch prevents the:

The chilled water flow switch prevents the:



a. Cooling tower fan from starting if chilled water flow has not been established
b. Cooling tower fan from starting if cooling water flow has not been established
c. Refrigeration compressor from starting if chilled water flow has not been established
d. Refrigeration compressor from starting if cooling water flow has not been established
e. Refrigeration compressor from starting if cooling tower fan has not been started







Answer: C

When pumping down a refrigeration system it is recommended to leave _______ residual pressure in the system to prevent air being drawn in through minor leaks or compressor shaft seals.

When pumping down a refrigeration system it is recommended to leave _______ residual pressure in the system to prevent air being drawn in through minor leaks or compressor shaft seals. 




a. 7 to 15 kPa abs
b. 5 to 15 kPa abs
c. 4 to 14 kPa abs
d. 7 to 14 kPa abs
e. 10 to 20 kPa abs








Answer: D

Oil added to refrigeration compressors

Oil added to refrigeration compressors




a) is done when the compressor discharge valve is closed
b) is done with a vacuum on the crankcase
c) is done with the equalizing valve closed
d) is done with the charging line open
e) must be preheated









Answer: B

When charging a refrigeration system it

When charging a refrigeration system it




a) should be done to the condenser
b) should be done with the cooling water shut off
c) should be done to the receiver
d) should be done with the compressor off
e) should be done with the liquid line shutoff valve closed







Answer: E

Charging a refrigeration system

Charging a refrigeration system




a) is done with the expansion valve closed
b) is done by adding refrigerant between the liquid shutoff valve and the expansion valve
c) is done with the compressor shut down
d) is done between the condenser and the receiver
e) is done between the suction valve and the compressor







Answer: B

A sulphur candle is a test for

A sulphur candle is a test for




a) freon leaks
b) ammonia leaks
c) air leaks
d) vacuum seal
e) CFC leaks







Answer: B

Which of the following is not a recommended step for the procedure in which dry nitrogen is used for a system leak test?

Which of the following is not a recommended step for the procedure in which dry nitrogen is used for a system leak test?





a) Remove controls and relief valves which may be damaged by the test pressure.
b) Connect the nitrogen cylinder to the system charging valve.
c) Close the liquid line shut-off valve.
d) Open the liquid line shut-off valve.
e) Set the pressure reducing valve for the minimum design pressure of the high side.





Answer: D

Leak testing on a refrigeration system

Leak testing on a refrigeration system





a) is done with a sulphur stick for freon refrigerant
b) is done with litmus paper for freon
c) is done with a sulphur candle for ammonia
d) must be done with the compressor running
e) is done with a vacuum on the system








Answer: C

Positive pressure testing of a new refrigeration system may be done

Positive pressure testing of a new refrigeration system may be done




a. Using litmus paper
b. By filling the system with oxygen
c. By filling the system with ammonia
d. By filling the system with an inert gas
e. By filling the system with softened water







Answer: D

The initial refrigerant charge is added to

The initial refrigerant charge is added to




a. The high-pressure side of the system
b. At the suction of the compressor
c. The evaporator
d. The expansion valve
e. The heat exchanger







Answer: A

When initially charging a refrigeration system:

When initially charging a refrigeration system:





a. the liquid line shutoff valve must be open
b. the system is charged with liquid refrigerant
c. the compressor must be locked and tagged out
d. the refrigerant container must be connected to the compressor suction
e. liquid is added until the receiver is full







Answer: B

The refrigerant liquid charging valve connection is:

The refrigerant liquid charging valve connection is:




a. On the condenser
b. On the compressor suction crossover valve
c. On the liquid line after the liquid shutoff valve
d. On the liquid receiver
e. Between the evaporator and the compressor inlet







Answer: C

Which of the following statements about adding oil to a system is true?

Which of the following statements about adding oil to a system is true?




a. Oil is added by charging it into the crankcase
b. Because the crankcase is pressurized it is not possible for air to get in the system when adding oil
c. Oil cannot be added while the compressor is in operation
d. The system must be recharged, purged and re-pressurized after the oil has been added.
e. For most compressors, oil is simply added through the dipstick tube.







Answer: A

Which of the following statements about manual refrigeration system purgers is false?

Which of the following statements about manual refrigeration system purgers is false?




a. Gas being vented into the atmosphere must pass through a beaker filled with water
b. The receiver and condenser should be purged separately
c. Purging rids the system of non-condensable gases
d. Purgers cause considerable loss of refrigerant
e. They must be operated on a regular schedule








Answer: D

The liquid line shutoff valve of a refrigeration system is:

The liquid line shutoff valve of a refrigeration system is:




a. Used when purging the system
b. A regulating valve
c. Used to relieve pressure
d. Closed when charging the system with liquid
e. On top of the receiver







Answer: D

What can cause a high discharge pressure in a refrigeration system?

What can cause a high discharge pressure in a refrigeration system?




a. Low evaporator level
b. Too much cooling water to the condenser
c. Over purging the unit
d. Excessive compressor operation
e. Unit is over charged with refrigerant








Answer: E

It is very important to slowly open oil drain valves and plugs in the crankcase for which of the following reasons?

It is very important to slowly open oil drain valves and plugs in the crankcase for which of the following reasons?




a. The oil is very hot
b. Oil can never be drained below the critical minimum level
c. Residual pressure in the crankcase may blow refrigerant vapour and oil out
d. Old oil is contaminated with refrigerant and may be very acidic
e. The oil is very cold, and may cause freeze-burns








Answer: C

Which of the following statements about strainers is false?

Which of the following statements about strainers is false?





a. Strainers prevent foreign particles from damaging compressor valves
b. Piping must be disconnected to clean the strainer
c. Hermetic type compressors are equipped with a built-in suction strainer
d. Strainers typically consist of a fine mesh screen basket
e. The strainer is installed in the suction line








Answer: B

Which of the following statements about refrigeration pressure gauges is true?

Which of the following statements about refrigeration pressure gauges is true?





a. They indicate pressures and corresponding temperatures in a system.
b. Dials on refrigeration pressure gages do not indicate saturation temperature
c. Only one pressure gage is normally installed on a system
d. Smaller systems have no provisions for the installation of pressure gages
e. Permanently installed pressure gages shall be constructed for at least 1.5 times the design pressure






Answer: A

The emergency discharge line of a refrigeration system:

The emergency discharge line of a refrigeration system:




a. Is located only on the condenser
b. Must have a manually-operated emergency discharge valve outside the building
c. Is required on all sizes of refrigeration systems
d. Is connected to the liquid space of the receiver
e. Must be painted bright yellow








Answer: B

A refrigeration system contains 30 kg of an A1 refrigerant. Which of the following system locations does NOT require a stop valve, according to CSA B52 code?

A refrigeration system contains 30 kg of an A1 refrigerant. Which of the following system locations does NOT require a stop valve, according to CSA B52 code?




a. Suction inlet of each compressor
b. Discharge outlet of each compressor
c. Suction inlet of each condensing unit
d. Discharge outlet of each condensing unit
e. Suction inlet of each liquid receiver







Answer: E

One function of vibration absorbers is to:

One function of vibration absorbers is to:




a. Lower noise levels
b. Allow the load on the system to increase dramatically without straining the components in the system
c. Increase longevity of the system
d. Insulate piping and make the system more efficient
e. Align piping






Answer: A

A pressure relief device on a refrigeration system shall have sufficient capacity to prevent the pressure in the pressure vessel from rising more than _____ above the setting of the pressure relief device.

A pressure relief device on a refrigeration system shall have sufficient capacity to prevent the pressure in the pressure vessel from rising more than _____ above the setting of the pressure relief device.





a. 10%
b. 15%
c. 103 kPa
d. 25%
e. 50%







Answer: A

One method of controlling the capacity of reciprocating compressors is to bypass the discharge from one or more cylinders back to the suction side of the compressor. The control is called

One method of controlling the capacity of reciprocating compressors is to bypass the discharge from one or more cylinders back to the suction side of the compressor. The control is called




a) compressor unloading
b) damping
c) suction throttling
d) cylinder bypass
e) sectional evaporating






Answer: D

Which of the statements about automatic expansion valves is false?

Which of the statements about automatic expansion valves is false?



a) The valve maintains constant pressure in the evaporator during compressor operation regardless of the load.
b) When the compressor stops the valve automatically shuts off.
c) A spring exerting a downward force on the diaphragm tends to open the valve.
d) The spring force is countered by evaporator pressure acting upward against the diaphragm which closes the valve.
e) The control may be used with multiple cooling coils connected to the same compressor.







Answer: E

A method of controlling the capacity of reciprocating refrigeration compressors, whereby the discharge of high-pressure refrigerant is re-introduced to the suction side of the compressor, is called:

A method of controlling the capacity of reciprocating refrigeration compressors, whereby the discharge of high-pressure refrigerant is re-introduced to the suction side of the compressor, is called:



a. Compressor unloading
b. Cylinder throttling
c. Suction throttling
d. Hot gas bypass
e. Cylinder unloading






Answer: D

The simple, small-bore device that restricts the flow of liquid from the condenser to the evaporator and maintains a pressure difference between the two, is called:

The simple, small-bore device that restricts the flow of liquid from the condenser to the evaporator and maintains a pressure difference between the two, is called:



a. A high-pressure float valve
b. A low-pressure float valve
c. An equalizer line
d. A capillary tube
e. An intermediate valve (pressure reducing valve)





Answer: D

The type of operation that stops a refrigeration compressor when the temperature setpoint of the cooled substance is reached, then re-starts the compressor when the temperature set-point is exceeded, is called:

The type of operation that stops a refrigeration compressor when the temperature setpoint of the cooled substance is reached, then re-starts the compressor when the temperature set-point is exceeded, is called:



a. Intermittent operation
b. Continuous operation with reduced output
c. Cylinder bypass
d. Unloading
e. Variable guide vane operation






Answer: A

Which of the following statements about the evaporator bypass dampers in a refrigeration system is true?

Which of the following statements about the evaporator bypass dampers in a refrigeration system is true? 




a. They decrease the resistance to the passage of air when they close
b. When the face damper is closed, the quantity of air passing over the evaporator coils is at a maximum
c. The quantity of air passing through the duct depends on the damper position
d. Multi-speed blowers cannot be used in combination with face and bypass dampers
e. Actuators are required to provide damper movement





Answer: E

The automatic expansion valve in a refrigeration system operates on the principle of balancing:

The automatic expansion valve in a refrigeration system operates on the principle of balancing:



a. The volumetric expansion of a fluid against a return spring
b. Evaporator temperature against a return spring
c. Condenser pressure against a return spring
d. Condenser temperature against a return spring
e. Evaporator pressure against a return spring







Answer: E

In refrigeration systems, the most common methods used to control the capacity of a reciprocating compressor are:

In refrigeration systems, the most common methods used to control the capacity of a reciprocating compressor are:



a. Cylinder bypass and hot gas bypass
b. Intermittent operation and continuous operation
c. Cylinder unloaders and variable speed drives
d. Suction throttling and variable inlet vanes
e. Cylinder unloaders and cylinder bypass






Answer: B

What will the effect be if insufficient liquid refrigerant is admitted to the evaporator by a thermostatic expansion valve?

What will the effect be if insufficient liquid refrigerant is admitted to the evaporator by a thermostatic expansion valve?



a. Insufficient force will be generated against the diaphragm and spring to open the expansion valve
b. The heat in the vapour leaving the evaporator causes the pressure in the thermal element to increase opening the expansion valve
c. The room temperature will decrease closing the expansion valve
d. The thermal element reaches an equilibrium leaving the expansion valve in the same position
e. The expansion valve will fail to respond





Answer: B

Sectional evaporators, installed in a refrigeration plant, control their capacity by

Sectional evaporators, installed in a refrigeration plant, control their capacity by



a. Varying the quantity of air passing over the evaporator coils
b. Intermittent operation of the compressor
c. Using solenoid valves to stop the refrigerant flow to one or more evaporator sections
d. Altering the evaporator pressure in one or more of the evaporator sections
e. Switching gear in the compressor




Answer: C

The thermostatic expansion valve operates on the principle of balancing:

The thermostatic expansion valve operates on the principle of balancing:




a. The volumetric expansion of a fluid against a return spring
b. Evaporator temperature against a return spring
c. Condenser pressure against a return spring
d. Condenser temperature against a return spring
e. Evaporator pressure against a return spring






Answer: A

In a refrigeration system, a weighted valve pin is used in a high-pressure float valve system in order to:

In a refrigeration system, a weighted valve pin is used in a high-pressure float valve system in order to:



a. Get proper pressure drop into the evaporator
b. Reduce frosting of the line immediately after the float valve
c. Allow the room temperature to be adjusted
d. Act as a pressure relief device
e. Prevent flooding of the evaporator






Answer: B

The control used in a mechanical refrigeration system to maintain a constant level of liquid refrigerant in the accumulator tank of a flooded evaporator is called

The control used in a mechanical refrigeration system to maintain a constant level of liquid refrigerant in the accumulator tank of a flooded evaporator is called




a. A thermostatic expansion valve
b. An automatic expansion valve
c. A low-pressure float valve
d. A hand operated expansion valve
e. A high-pressure float valve





Answer: C

Manual or hand-operated expansion valves are seldom used in modern refrigeration systems except, occasionally:

Manual or hand-operated expansion valves are seldom used in modern refrigeration systems except, occasionally:



a. To control the temperature of the evaporator
b. In the bypass line around the automatic control valve
c. To control the temperature of the cooling medium
d. In the compressor oil cooling system
e. To control the temperature of the condenser




Answer: B

Safety controls serve what function?

Safety controls serve what function?



a) They stop operation if the temperature gets too high.
b) They stop operation when the pressure gets too high.
c) They stop operation when the pressure is too low.
d) They stop operation when the temperature is too low.
e) All of the above





Answer: E

The CSA B52 code requires that pressure limiting devices shall be provided on all systems operating above atmospheric pressure, except on a factory sealed system containing less than _____ of group A1 refrigerant:

The CSA B52 code requires that pressure limiting devices shall be provided on all systems operating above atmospheric pressure, except on a factory sealed system containing less than _____ of group A1 refrigerant:



a. 9 kg
b. 7 kg
c. 10 kg
d. 5 kg
e. 3 kg






Answer: C

With regard to their application in refrigeration systems, which of the following statements about flow switches is false?

With regard to their application in refrigeration systems, which of the following statements about flow switches is false?




a. They are used on chilled water systems
b. They are used as shutdowns or permissives when flow is insufficient
c. They are operated by the force exerted on a flexible vane immersed in the fluid flowing in the line
d. They can only be used to regulate liquid flow, not air flow
e. They can be used to close flow indicator circuits





Answer: D

The oil-pressure failure switches of a mechanical refrigeration system

The oil-pressure failure switches of a mechanical refrigeration system




a. keep the compressor oil pressure at a level where the oil will not freeze
b. prevent compressor start-up if the oil heater fails
c. separate refrigerant dissolved in the oil from the lubricant
d. shut down the compressor when the oil pressure drops below the minimum required value
e. keep the oil from freezing at low pressure





Answer: D

The expansion valve in a refrigeration system

The expansion valve in a refrigeration system



a. Expands the liquid to the receiver
b. Relieves high pressure in the receiver
c. Regulates the liquid refrigerant flow to the evaporator
d. Is used to charge the refrigeration system
e. Isolates the compressor from the condenser






Answer: C

With regard to a refrigeration system pressurestat, which of the following statements is false?

With regard to a refrigeration system pressurestat, which of the following statements is false?




a. The control is connected to the suction line of the compressor
b. The control consists of a switch actuated through a linkage arrangement connected to a bellows or diaphragm
c. A pressurestat can be used in conjunction with an automatic expansion valve
d. When the pressure drops to the minimum allowable the switch acts opposite to a thermostat and opens
e. A pressurestat cannot be used with a capillary tube






Answer: C

Which one is NOT true about the shell and tube condenser?

Which one is NOT true about the shell and tube condenser?



a. High maintenance cost
b. High cooling efficiency
c. Cleaned easily
d. Used in medium to large air conditioning installations





Answer: A

The purpose of a condenser in a refrigeration system is

The purpose of a condenser in a refrigeration system is




a) to remove the sensible heat from the refrigerant
b) to remove the latent heat from the refrigerant
c) to cool the liquid refrigerant
d) to vaporize the liquid refrigerant
e) to reduce the pressure in the evaporator





Answer: B

Which of the following statements about the shell and tube evaporator type is false?

Which of the following statements about the shell and tube evaporator type is false?




a) It is also known as a chiller.
b) This type of evaporator cools mainly liquids.
c) The refrigerant is circulating in the shell in the flooded operation.
d) Refrigerant vapour is drawn out of the evaporator by the compressor.
e) The liquid to be cooled circulates through the tubes in the direct-expansion operation.







Answer: E

The amount of water used in the evaporative condenser of a refrigeration plant is only a small percentage of that used in a water condenser of the same capacity, because

The amount of water used in the evaporative condenser of a refrigeration plant is only a small percentage of that used in a water condenser of the same capacity, because



a. Evaporating condensers also use air to cool the refrigerant
b. The evaporating condensers spray refrigerated water onto condensing coil
c. The cooling water evaporates, removing far more heat per kilogram of system coolant
d. Of water conservation methods
e. Of the scarcity of water in locations that use evaporative condensers






Answer: C

Which of the following statements about the shell and tube refrigeration evaporator is false?

Which of the following statements about the shell and tube refrigeration evaporator is false?



a. It is also known as a chiller
b. The brine circulates through the tubes in a direct-expansion chiller
c. The refrigerant is contained in the shell, and surrounds the tubes, in the flooded chiller
d. Refrigerant vapour is drawn out of the evaporator by the compressor
e. This type of evaporator cools mainly liquids





Answer: B

All refrigeration evaporators:

All refrigeration evaporators:



a. require regular defrosting
b. are part of the high side of the system
c. are located between the expansion valve and the king valve.
d. are flooded with refrigerant
e. boil liquid refrigerant at low pressure and low temperature







Answer: E

Which of the following statements about double tube refrigeration condensers is true?

Which of the following statements about double tube refrigeration condensers is true?



a. They consist of two separate tubes side by side
b. They are easy to clean
c. Water flows in the inner tube in the opposite direction of the flow of refrigerant
d. They have the highest efficiency of the water-cooled condensers
e. They have a large cooling capacity combined with a small size.




Answer: C

With regard to refrigeration systems, large-capacity air-cooled condensers are found mainly

With regard to refrigeration systems, large-capacity air-cooled condensers are found mainly



a. on roof tops
b. in indoor mechanical rooms, with ductwork supplying cooling air
c. in locations where water is plentiful
d. where they are protected from the environment
e. in systems where the high-side pressure does not exceed 103 kPa





Answer: A

Dry and flooded evaporators differ principally in what respect?

Dry and flooded evaporators differ principally in what respect?



a. The dry evaporator is designed to cool gases only
b. The heat transfer surfaces of a flooded evaporator are kept covered with liquid refrigerant
c. Flooded systems primarily use B1 and B2 refrigerants
d. Dry evaporators use low-side floats, whereas flooded evaporators use high-side floats
e. The drift eliminators in a dry evaporator are considerably smaller







Answer: B

A compressor seal is required to prevent:

A compressor seal is required to prevent:




a. Refrigerant and oil leakage into the compressor
b. Refrigerant and oil leakage along the shaft
c. Prevent moisture from escaping the compressor
d. Prevent dirt and moisture from leaving the compressor






Answer: B

The function of a safety heads is to:

The function of a safety heads is to:



a. Relieve the pressure of compression when the compressor cycles off
b. Relieve the pressure in the cylinder if a liquid slug of refrigerant is in the cylinder
c. Protect the compressor from over heating
d. Protect the compressor from short cycling








Answer: B

Consider a single stage, single acting reciprocating compressor. Calculate the piston displacement in cubic metres per minute, if given the following: piston stroke 12 cm piston diameter 10 cm piston speed 1100 working strokes per minute

Consider a single stage, single acting reciprocating compressor.
Calculate the piston displacement in cubic metres per minute, if given the following:
piston stroke 12 cm
piston diameter 10 cm
piston speed 1100 working strokes per minute



a. 1.031
b. 1.033
c. 1.035
d. 1.037
e. 1.039








Answer: D

Packing gland seals are used on what compressor?

Packing gland seals are used on what compressor?




a. Open type
b. Hermetic type
c. Large capacity ammonia compressor
d. Rotating sliding vane design
e. Helical rotor design







Answer: C

Shaft seals are used on what compressor?

Shaft seals are used on what compressor?



a. Open type
b. Hermetic type
c. Stationary single-blade design
d. Rotating sliding vane design
e. Helical rotor design








Answer: A

Advantages of the centrifugal compressor are?

Advantages of the centrifugal compressor are?




a. No moving parts
b. Can be coupled to an electric motor
c. Cheap
d. A and B
e. All of the above







Answer: D

Rotary compressor types are?
i. Open type
ii. Hermetic type
iii. Stationary single-blade design
iv. Rotating sliding vane design
v. Helical rotor design



a. iii, iv,v
b. i, ii, iii
c. ii, iv, v
d. i, iii, iv
e. ii, iii, iv






Answer: A


In a refrigeration system, the purpose of the compressor is to

In a refrigeration system, the purpose of the compressor is to




a) establish two pressure levels
b) reject the heat from the system
c) absorb the heat into the system
d) regulate the flow of the refrigerant
e) heat the refrigerant








Answer: A

Which of the following is the compressor responsible for doing? i) Maintains a high pressure in the condenser ii) Maintains a low pressure in the evaporator iii) Raises the pressure of the refrigerant

Which of the following is the compressor responsible for doing?
i) Maintains a high pressure in the condenser
ii) Maintains a low pressure in the evaporator
iii) Raises the pressure of the refrigerant



a) i only
b) both i and iii
c) both ii and iii
d) iii only
e) i, ii, and iii








Answer: E

Which of the following is not a function of the compressor in a refrigeration system?

Which of the following is not a function of the compressor in a refrigeration system?




a) draw low pressure refrigerant out of the evaporator
b) draw low temperature refrigerant out of the evaporator
c) lower the temperature of the refrigerant
d) maintain sufficiently low pressure in the evaporator
e) raise the pressure of the refrigerant








Answer: C

The pressure ratio of a refrigeration compressor can be calculated by dividing the:

The pressure ratio of a refrigeration compressor can be calculated by dividing the:




a. Discharge gage pressure by the inlet gage pressure
b. Swept volume of a cylinder by its clearance volume
c. Absolute inlet pressure by the absolute discharge pressure
d. Absolute discharge pressure by the absolute inlet pressure, and then multiplying by the number of cylinders
e. Absolute discharge pressure by the absolute inlet pressure







Answer: E

Refrigerant compressors:

Refrigerant compressors:




a. Must have intercoolers
b. Could be centrifugal type
c. Use automotive-style suction and discharge valves
d. Have more cooling fins than air compressors
e. Discharge directly into the evaporator







Answer: B

Which of the following is NOT a function of the refrigeration compressor?

Which of the following is NOT a function of the refrigeration compressor?





a. Raises the pressure of the refrigerant
b. Raises the temperature of the refrigerant
c. Maintains a low pressure in the evaporator
d. Circulates refrigerant through the system
e. Removes energy from the vapour







Answer: E

A stationary crankshaft seal used on refrigeration compressors, which consists of a metallic bellows soldered at one end to a ring, and which presses against a shoulder on the shaft is called a:

A stationary crankshaft seal used on refrigeration compressors, which consists of a metallic bellows soldered at one end to a ring, and which presses against a shoulder on the shaft is called a:




a. Packing gland seal
b. Diaphragm seal
c. Bellows seal
d. Rotating Mechanical seal
e. Set screw







Answer: C

For a Helical Rotor Design rotary refrigeration compressor, which of the following statements is true?

For a Helical Rotor Design rotary refrigeration compressor, which of the following statements is true?



a. The compressor consists of three opposing grooved rotors
b. The driving rotor has less helical lobes than the driven rotor has flutes
c. The vapour is drawn in via the closed space between the driving rotor and the casing
d. The cylinders around the rotor screws must be considerably larger in diameter than the screws
e. The compressor is reversible, to allow it to be used in heat pump applications









Answer: B

A negative factor of Hermetic Type refrigeration compressors is:

A negative factor of Hermetic Type refrigeration compressors is:




a. They are too large to be used in any application except large industrial plants
b. The drive motor tends to overheat
c. Shaft sealing is difficult
d. Field servicing is not possible
e. It is difficult to replace the shaft coupling








Answer: D

The safety head of a refrigeration compressor is designed to:

The safety head of a refrigeration compressor is designed to:




a. Unload over-loaded cylinders
b. Be installed on a hermetic compressor
c. Relieve pressure due to liquid in the cylinder
d. Prevent explosion damage
e. Operate in place of a safety relief valve








Answer: C

Refrigerant compressors:

Refrigerant compressors:




a. Must have intercoolers
b. Could be centrifugal type
c. Use automotive-style suction and discharge valves
d. Have more cooling fins than air compressors
e. Discharge directly into the evaporator







Answer: B

The piston displacement of a reciprocating refrigeration compressor is defined as:

The piston displacement of a reciprocating refrigeration compressor is defined as:




a. The distance along which the piston travels
b. The cylinder bore
c. Volume of refrigerant that can be circulated through all the cylinders per unit time
d. The revolutions per minute of the compressor motor
e. Piston stroke length








Answer: C

The three main classifications of refrigeration compressors are:

The three main classifications of refrigeration compressors are:





a. Scroll, rotary, and positive displacement
b. Axial, centrifugal, and positive displacement
c. Centrifugal, dynamic, and positive displacement
d. Reciprocating, rotary, and centrifugal
e. Rotary, reciprocating, and lobe








Answer: D

Refrigerant evaporators

Refrigerant evaporators




a) always have the refrigerant on the shell side
b) are located between the expansion valve and the receiver
c) may have brine pumped past the coils in an indirect system
d) may be of the walk-in type
e) are usually oil cooled







Answer: C

Which of the following statements about a system that circulates warm brine or water back to a chiller tank is true?

Which of the following statements about a system that circulates warm brine or water back to a chiller tank is true?




a) The system is a direct refrigeration system.
b) The evaporator in the system is located in direct contact
with the material being refrigerated.
c) The brine or water is the refrigerant.
d) The evaporator cools the brine or water.
e) All of the above.








Answer: D

Choose the true statement. The economiser of a packaged water chiller, used for air conditioning, does NOT

Choose the true statement. The economiser of a packaged water chiller, used for air conditioning, does NOT



a. Have an intercooling effect on the compressor
b. Reduce the power required for compression of the refrigerant
c. Reduce the flash vapour in the evaporator
d. Increase the refrigerating capacity of a system
e. Eliminate liquid carryover to the compressor







Answer: E

Which of the following is not an advantage of a factory assembled, packaged refrigeration unit?

Which of the following is not an advantage of a factory assembled, packaged refrigeration unit?





a. Components are designed to match each other
b. The final installation must be according to code
c. The unit is equipped with all the required auxiliary equipment
d. Space requirements are minimized
e. The unit is factory tested in operation







Answer: B

The brine pump of a refrigeration system:

The brine pump of a refrigeration system:




a. Circulates the refrigerant through the evaporator
b. Pumps brine through the condenser cooling circuits
c. Circulates the brine through the cooling circuits
d. Maintains the brine level in the cooling circuit
e. Is used to remove heat from the condenser









Answer: C

In the evaporator of a refrigeration system:

In the evaporator of a refrigeration system:




a. The refrigerant rejects heat to the cooling tower
b. The refrigerant absorbs heat from the compressor cooling system
c. The refrigerant absorbs heat from the surrounding medium
d. The surrounding medium evaporates
e. The refrigerant is condensed







Answer: C

In the condenser of a refrigeration system:

In the condenser of a refrigeration system:





a. Latent heat is restored to the refrigerant
b. The surrounding medium must be hotter than the refrigerant
c. The heat in the refrigerant given up in the evaporator must be restored
d. The condensing medium absorbs heat from the refrigerant
e. The high pressure vapour is converted to low pressure liquid.






Answer: D

The temperature in the evaporator:

The temperature in the evaporator:





a. Depends on pressure in the receiver
b. Will decrease when the compressor stops
c. Depends on pressure in the evaporator
d. Depends on the ambient temperature
e. Is controlled by the charging valve






Answer: C

With regard to economizers installed on packaged air-conditioning chillers, which of the following statements is false?

With regard to economizers installed on packaged air-conditioning chillers, which of the following statements is false?





a. Economizers control the flow of liquid refrigerant from the evaporator to the condenser
b. Liquid refrigerant levels in each chamber are controlled by float operated, valves
c. The upper float chamber is connected to the bottom of the condenser
d. The economizer float chamber is connected via the motor to the second stage inlet of the compressor
e. It is composed of two chambers









Answer: A

For a direct expansion compression refrigeration system, which of the following statements is true?

For a direct expansion compression refrigeration system, which of the following statements is true?





a. The evaporator in this system is never in direct contact with the material or space being refrigerated
b. For large systems calcium chloride brine is cooled by the evaporator then pumped to the area being refrigerated
c. Water cooled by the chiller evaporation coils is used to refrigerate below 0°C
d. The evaporator can be located in air circulating ducts communicating with the material or space being refrigerated
e. A direct expansion system is not the same type of system as the direct refrigeration system








Answer: D

In the condenser of a refrigeration system:

In the condenser of a refrigeration system:



a. Latent heat is restored to the refrigerant
b. The surrounding medium must be hotter than the refrigerant
c. The heat in the refrigerant given up in the evaporator must be restored
d. The condensing medium absorbs heat from the refrigerant
e. The high pressure vapour is converted to low pressure liquid.







Answer: D

A purpose of a liquid refrigerant control or regulating valve (expansion valve)is to:

A purpose of a liquid refrigerant control or regulating valve (expansion valve)is to:




a. Drain the receiver
b. Regulate the refrigerant flow to the condenser
c. Maintain a constant level in the receiver
d. Regulate the cooling water to the condenser
e. Meter the flow of refrigerant to the evaporator in response to the evaporator load






Answer: E

A controlled amount of high temperature, high pressure liquid refrigerant:

A controlled amount of high temperature, high pressure liquid refrigerant:




a. Passes through the regulating valve to the evaporator
b. Passes through the regulating valve to the liquid receiver
c. Passes through the compressor to the condenser
d. Evaporates in the evaporator, leaving mostly refrigerant liquid at the evaporator outlet
e. Occurs in isenthalpic systems






Answer: A

A refrigeration system circulates warm brine back to a chiller. Which of the following statements about this system is true?

A refrigeration system circulates warm brine back to a chiller. Which of the following statements about this system is true?




a. The condenser in the system is located in direct contact with the material being refrigerated
b. The evaporator in the system is located in direct contact with the material being refrigerated
c. The brine or water is the refrigerant
d. The evaporator cools the brine
e. The system is a direct refrigeration system






Answer: D

The enthalpy of a vapour is

The enthalpy of a vapour is


a. Sensible heat of a liquid
b. Sensible heat of a liquid plus latent heat of evaporation
c. Latent heat of evaporation





Answer: B

Leakage tendency is determine by:

Leakage tendency is determine by:




a. Operating pressure
b. Viscosity
c. Density
d. Molecular mass
e. All of the above






Answer: E

The larger the difference between the temperature of the liquid refrigerant entering the evaporator and the actual evaporator temperature:

The larger the difference between the temperature of the liquid refrigerant entering the evaporator and the actual evaporator temperature:



a. The larger the refrigerating effect will be
b. The smaller the refrigerating effect will be
c. The larger the latent heat will be
d. The smaller the latent heat will be
e. The smaller the sensible heat will be






Answer: B

Which one of the following should a ideal refrigerant should NOT have?

Which one of the following should a ideal refrigerant should NOT have?




a. A low boiling point at atmospheric pressure
b. A high latent heat capacity: that is, it should require a large amount of heat to convert it from a liquid to a gas after its boiling point has been reached
c. A fairly low condensing pressure
d. An offensive odour
e. A nonpoisonous nature
f. A noncorrosive action on metals
g. A nonflammable and nonexplosive nature when mixed with air
h. A reasonable price







Answer: D

The refrigerating effect of a refrigerant is:

The refrigerating effect of a refrigerant is:




a. Equal to its latent heat of vaporization
b. Greater than its latent heat of vaporization
c. Less than its latent heat of vaporization
d. Equal to its specific heat capacity
e. Less than its net-refrigerating effect




Answer: A

R-22:

R-22:



a. Is non-toxic
b. Has a strong, pungent odour
c. Is explosive when mixed with air
d. Is highly toxic
e. Is not an ozone-depleting substance






Answer: A

What is the name of the refrigerant that has the following characteristics? It is non-flammable, odourless, non-toxic, it does not have a corrosive effect on metal if water is present and at atmospheric pressure it has a boiling point of approximately -40.6°C.

What is the name of the refrigerant that has the following characteristics? It is non-flammable, odourless, non-toxic, it does not have a corrosive effect on metal if water is present and at atmospheric pressure it has a boiling point of approximately -40.6°C.



a. Ammonia
b. R-22
c. R-744R
d. R-134a
e. R-290







Answer: B

Group "A" refrigerants are:

Group "A" refrigerants are:



a. Non-flammable
b. Low-flammable
c. Low-toxic
d. Low-toxic and flammable
e. High-toxic and flammable







Answer: C

The ideal refrigerant should:

The ideal refrigerant should:



a. Have a low latent heat capacity
b. Have a high boiling point
c. Have high condensing pressure
d. Be environmentally friendly
e. Be easily detected because of its strong odour.







Answer: D

The latent heat of fusion of ice is:

The latent heat of fusion of ice is:




a. The sensible heat required for melting ice
b. 335 kJ per kg
c. 335 kJ per ton
d. The latent heat required for evaporation of ice
e. 4.2 kJ per gram





Answer: B

The standard refrigeration cycle is used to compare refrigerants and machines operating under comparable conditions. These standard conditions are:

The standard refrigeration cycle is used to compare refrigerants and machines operating under comparable conditions. These standard conditions are:



a. 1030 kPa and atmospheric pressure
b. 30°C condensing and -15°C evaporating
c. 30 kPa and atmospheric pressure
d. -30°C condensing and 15°C evaporating
e. 30 kPa and atmospheric temperature






Answer: B

Ammonia, as well as being toxic, is also :

Ammonia, as well as being toxic, is also :



a. Miscible
b. Odourless
c. Flammable
d. Dense
e. A low pressure refrigerant






Answer: C

Ammonia refrigerants:

Ammonia refrigerants:



a. Have high sensible heat capacity
b. Mix well with oil
c. Are very expensive
d. Are well suited for industrial refrigeration
e. Are ideally suited to copper piping system






Answer: D

R-22 refrigerant is:

R-22 refrigerant is:



a. Not miscible with oil
b. Mostly used in packing plants
c. Corrosive on copper
d. Corrosive on aluminum
e. A heat transferring medium




Answer: E

Superheat the evaporator is defined as:

Superheat the evaporator is defined as:



a. The most efficient way to remove heat from a process
b. The heat required to accelerate the cooling process
c. The additional heat absorbed by a refrigerant after it has vaporized
d. The best heat available






Answer: C

One tonne of refrigeration is

One tonne of refrigeration is



a) 13958 kJ per day
b) 100 kJ per minute
c) 233 kJ per minute
d) 13958 J per hour
e) 335 J per second






Answer: C

Refrigerant mediums will evaporate

Refrigerant mediums will evaporate



a) when pressure is increased
b) when temperature is increased
c) when they are diluted
d) when temperature is decreased
e) when heat is removed






Answer: B

Which of the following statements about high-side pressure and temperature is true?

Which of the following statements about high-side pressure and temperature is true?



a) The heat flow is from the cooling medium to the hot refrigerant.
b) The condensing temperature of the vapour is 15 - 20 degrees C higher than the temperature of the medium used in the condenser.
c) The condensation temperature of the refrigerant will be lower if the pressure of the vapourized refrigerant is lowered.
d) The condenser functions by taking latent heat from the surrounding air and adding it as sensible heat to the refrigerant.
e) None of the above







Answer: B

Which of the following statements about low-side pressure and temperature is false?

Which of the following statements about low-side pressure and temperature is false?



a) The evaporation temperature of the refrigerant should be 5 - 10 degrees C higher than that of the cooled medium.
b) For a given amount of heat transfer an oversized evaporator can be operated at a higher temperature.
c) The low side pressure depends on the type of evaporation used.
d) The evaporation temperature of the refrigerant will be
higher if the evaporator lowers the refrigerant pressure.
e) All of the above.







Answer: A

The function of the condenser is to

The function of the condenser is to




a) vaporize the liquid refrigerant
b) change high pressure refrigerant vapour to liquid
c) pressurize low pressure refrigerant vapour
d) vent off vaporized refrigerant
e) lower the liquid refrigerant pressure





Answer: B

In the case of a simple ice box which of the following heat transfers is correct?

In the case of a simple ice box which of the following heat transfers is correct?



a) Air loses latent heat, ice does not gain any heat.
b) Air loses sensible heat, ice does not gain any heat.
c) Air loses sensible heat, ice gains sensible heat.
d) Air loses sensible heat, ice gains latent heat.
e) Air loses latent heat, ice gains latent heat.







Answer: D

The net refrigerating effect of a refrigerant is the amount of heat:

The net refrigerating effect of a refrigerant is the amount of heat:



a. Discharged by the condenser
b. Absorbed by the refrigerant in the evaporator
c. Absorbed by the refrigerant in the condenser
d. Discharged by the refrigerant in the evaporator
e. Absorbed by the evaporator





Answer: B
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