Chap. 117, 118, 119, 120, 121, 122,123 & 124

Question 1

The two types of evaporators, dry evaporators and flooded evaporators differ principally in what respect?

a) the dry evaporator cannot cool liquids
b) method of refrigerant circulation
c) type of refrigerant used
d) size of the evaporator
e) field maintenance availability of the types

Answer 1

b) method of refrigerant circulation

Question 2

An evaporator that contains only a small amount of liquid refrigerant at any time is what type of evaporator?

a) Dry evaporator
b) Flooded evaporator
c) Wet evaporator
d) All of the above
e) None of the above

Answer 2

a) Dry evaporator

Question 3

Refrigerant evaporators:

a) are only used in ammonia systems
b) are part of the high side of the system
c) are used to transfer oil
d) are only used with very high pressure refrigeration systems
e) are used to transfer heat

Answer 3

e) are used to transfer heat

Question 4

The evaporator which increases heat exchange by crimping thin metal plates to its form is which type of evaporator?

a) Plate surface
b) Bare tube
c) Shell and tube
d) Finned tube
e) none of the above

Answer 4

d) Finned tube

Question 5

An evaporator which can easily be cleaned and defrosted manually without interrupting the cooling process is which type of evaporator?

a) Bare finned
b) Finned
c) Plate surface
d) Shell and tube
e) None of the above

Answer 5

c) Plate surface

Question 6

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 6

e) The liquid to be cooled circulates through the tubes in the direct-expansion operation

Question 7

Air-cooled condensers of large capacity are found mainly in which of the following locations?

a) roof tops
b) closed rooms with low air circulation
c) warm dry rooms
d) cold rooms with low air circulation
e) any of the above

Answer 7

a) roof tops

Question 8

Which of the following statements about double tube
condensers is true?
a) It consists of two separate tubes side by side.
b) It cannot be used with air cooled condensers.
c) Water flow in the inner tube is in the opposite direction of the flow of refrigerant.
d) It has the highest efficiency of the water-cooled
condensers.
e) It is a small condenser for a large capacity system

Answer 8

c) Water flow in the inner tube is in the opposite direction of the flow of refrigerant

Question 9

The condenser which is very expensive to clean and requires the tubes to be cleaned with acid and neutralized is the:

a) shell and tube condenser
b) shell and coil condenser
c) double tube condenser
d) evaporative condensers
e) baffle condensers

Answer 9

b) shell and coil condenser

Question 10

The amount of water used in an evaporative condenser is only a small percentage of that used in a water condenser of the same capacity. This is due primarily to what?
a) Evaporating condensers also use air to cool the
refrigerant.
b) The evaporating condensers spray refrigerated water onto condensing coil.
c) Water evaporating requires a large amount of latent heat.
d) Water being recirculated.
e) None of the above

Answer 10

c) Water evaporating requires a large amount of latent heat.

Question 11

The common types of water-cooled condensers used in refrigeration systems are:

1. the shell and tube
2. the shell and coil
3. the double tube
4. the plate surface
   a) 1, 2, 3
   b) 1, 3, 4
   c) 2, 3, 4
   d) 1, 2, 4
   e) 3, 4

Answer 11

a) 1, 2, 3

Question 12

Defective condenser operation is a result of the presence of all of the following except

a) scale forming chemicals
b) dirty cooling water
c) noncondensible gases
d) low coolant circulation
e) compressor lubricating oil

Answer 12

e) compressor lubricating oil

Question 13

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 13

b) to remove the latent heat from the refrigerant

Question 14

Starting, stopping or unloading of the compressor is usually done by all of the following operating controls except:
a) temperature actuated control
b) viscosity activated control
c) pressure activated control
d) humidity activated control
e) All of the above can control the starting, stopping or
unloading of the compressor

Answer 14

b) viscosity activated control

Question 15

The operating control which uses a bimetal element is a:

a) fluid expansion actuating control
b) pressure actuated control
c) humidity actuated control
d) temperature actuated control
e) solenoid actuated control

Answer 15

d) temperature actuated control

Question 16

Which of the following statements about pressure stats 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 pressure-stat 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 pressure-stat cannot be used with a capillary tube

Answer 16

c) A pressure-stat can be used in conjunction with an

automatic expansion valve

Question 17

The operating control which consists of a hygroscopic element made of material similar to multiple strands of human hair is called a:

a) humidistat
b) thermostat
c) fluid expansion regulator
d) pressure-stat
e) bimetal element

Answer 17

a) humidistat

Question 18

Which of the following actuating control valves is
electromagnetically operated?
a) Thermostat valve
b) Fluid expansion regulator valve
c) Evaporator pressure regulating valve
d) Condenser cooling water regulating valve
e) Solenoid valve

Answer 18

e) Solenoid valve

Question 19

In many cases evaporator pressure must not be allowed to drop below a certain level to prevent which of the following results?

a) frosting of coils
b) evaporator valve lock
c) tubing implosion
d) overheating of the evaporator
e) overheating of the compressor

Answer 19

a) frosting of coils

Question 20

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 20

e) All of the above

Question 21

Which of the following statements about flow switches is false?
a) They are used on chilled water.
b) They are used as lockout switches when flow is
insufficient.
c) They are operated by the force exerted on a flexible vane
immersed in the liquid flowing in the line.
d) They can only be used to regulate liquid flow (i.e. not air flow).
e) They can be used to close flow indicator circuits

Answer 21

d) They can only be used to regulate liquid flow (i.e. not air flow)

Question 22

The safety control which uses a current transformer with a resistor in the motor circuit is known as

a) high motor temperature cutup
b) low oil sump temperature protection
c) motor overload protection
d) solenoid valve
e) high oil temperature cutout

Answer 22

c) motor overload protection

Question 23

Oil pressure failure switches are used to perform which of the following functions?
a) Keep oil from freezing at low pressure.
b) Prevent compressor startup 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.
e) Keep the oil pressure at a level where the oil will
not freeze

Answer 23

d) Shut down the compressor when the oil pressure drops below the minimum.

Question 24

The most widely used refrigerant control which consists of a bellows or a diaphragm chamber connected to a temperature sensing bulb by means of a small capillary tube is a/an

a) thermostatic expansion valve
b) automatic expansion valve
c) low pressure float valve
d) hand operated expansion valve
e) high pressure float valve

Answer 24

a) thermostatic expansion valve

Question 25

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 downward against the diaphragm which closes the valve.
e) The control may be used with multiple cooling coils
connected to the same compressor

Answer 25

e) The control may be used with multiple cooling coils

connected to the same compressor

Question 26

Which control is used to maintain a constant level of liquid refrigerant in a flooded evaporator in the liquid reserve tank?

a) thermostatic expansion valve
b) automatic expansion valve
c) low pressure float valve
d) hand operated expansion valve
e) high pressure float valve

Answer 26

c) low pressure float valve

Question 27

The simple control which restricts the flow of liquid from the condenser to the evaporator and maintains a pressure difference between the two units by using a considerable pressure drop resulting from resistance between the devices length and small bore is called

a) a high pressure float valve
b) a low pressure float valve
c) a bypass line
d) a capillary tube
e) an external float chamber

Answer 27

d) a capillary tube

Question 28

In a system controlled by a high pressure float valve
insufficient liquid will cause which of the following
results?
a) automatic system shut down
b) boosting the compressors pressure
c) liquid being carried over to the compressor with the
vapour
d) starving the evaporator and reducing the capacity of the system
e) all of the above

Answer 28

d) starving the evaporator and reducing the capacity of the system

Question 29

One method of controlling the capacity of reciprocatingcompressors is to bypass the discharge from one or morecylinders back to the suction side of the compressor. The control is called

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

Answer 29

d) cylinder bypass

Question 30

Sectional evaporators control the capacity of the evaporator by which of the following means?

a) Varying the quantity of air being cooled passing over the evaporator coils.
b) Intermittent operation of the compressor.
c) Divided multipart evaporators which have refrigerant control valves which can be shut off independently as the load decreases.
d) Switching gears in the compressor.
e) Decreasing suction in the compressor

Answer 30

c) Divided multipart evaporators which have refrigerant control valves which can be shut off independently as the load decreases.

Question 31

Which of the following statements about evaporator dampers is true?

a) These dampers decrease the resistance to the passage of air.
b) When the damper is closed the quantity of air passing over the evaporator coils is at a maximum.
c) Depending on the damper position the quantity of air passing through the duct varies widely.
d) Multispeed blowers cannot be used in combination with evaporator dampers.
e) None of the above

Answer 31

e) None of the above

Question 32

The type of operation which stops the compressor when the desired low temperature of the substance to be cooled is reached and starts the compressor up again when the temperature rises to a set level is called:

a) intermittent operation
b) continuous operation with reduced output
c) cylinder bypass operation
d) unloading operation
e) variable guide operation

Answer 32

a) intermittent operation

Question 33

The control which is replacing suction throttling and
operates by swirling the refrigerant in the same direction as the compressor impeller, resulting in a reduction of power required by the compressor is which of the following controls?
a) Hot gas bypass
b) Cylinder bypass
c) Variable Inlet Guide Vanes
d) Damper control
e) Compressor unloader

Answer 33

c) Variable Inlet Guide Vanes

Question 34

A simple trap located in the suction line before the
compressor that collects liquid, where it evaporates and returns to the compressor as a gas, is called
a) an oil separator
b) a strainer-drier
c) a distributor
d) an accumulator
e) a stop valve

Answer 34

d) an accumulator

Question 35

Which of the following statements about strainers is false?
a) The strainer is installed in the suction line.
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) Strainers prevent foreign particles from damaging
compressor valves

Answer 35

b) Piping must be disconnected to clean the strainer.

Question 36

A chemical dot placed under the glass lens of a sight glass which is exposed to the liquid serves what function?

a) To monitor liquid flow
b) To monitor refrigerant levels
c) To monitor the presence of moisture
d) To monitor the presence of foreign particles
e) To monitor the pressure levels

Answer 36

c) To monitor the presence of moisture

Question 37

The function of vibration absorbers is to:

a) lower noise levels
b) reduce pipe hammer
c) increase longevity of the system
d) insulate piping and make the system more efficient
e) allow the load on the system to increase dramatically

Answer 37

a) lower noise levels

Question 38

Which of the following pipe joints should be used for high pressure 1 1/4 inch or smaller piping?

a) welded
b) screwed
c) soldered
d) flared
e) none of the above

Answer 38

b) screwed

Question 39

Moisture in a system can result in which of the following?

a) formation of ice
b) acid formation
c) corrosion
d) deterioration of motor insulation
e) all of the above

Answer 39

e) all of the above

Question 40

The accessory which maintains efficient heat transfer by collecting oil that coats the tubes of the condenser is called:

a) a strainer
b) a strainer-drier
c) an oil scrubber
d) a filter
e) an oil separator

Answer 40

e) an oil separator

Question 41

Which of the following statements about pressure gages 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 required for each system.
d) The pressure gage will not work if the system is equipped with pulsation dampeners.
e) None of the above.

Answer 41

a) They indicate pressures and corresponding temperatures in a system.

Question 42

A direct expansion type evaporator that has more than 1 refrigerant circuit in it requires what to have even refrigerant flow in each circuit?

a) A stop valve
b) A purge valve
c) A distributor
d) A purge valve
e) A thermal regulator

Answer 42

c) A distributor

Question 43

Emergency discharge is used to counter which of the following problems?

a) Dangerously low system pressures
b) Toxic refrigerant leaks
c) Combustion of flammable refrigerants
d) Dangerously high system pressures
e) All of the above

Answer 43

d) Dangerously high system pressures

Question 44

The emergency discharge line in a refrigeration system:

a) is located only on the condenser
b) should have a shut-off valve outside the building
c) is required on all sizes of refrigerating units
d) is located on the evaporator
e) is a vented sewer line

Answer 44

b) should have a shut-off valve outside the building

Question 45

Higher than normal head pressure is undesirable for all of the following reasons except:

a) it increases power consumption
b) it decreases condenser capacity
c) it reduces compressor capacity
d) it overstresses compressor parts
e) it is detrimental to compressor lubrication

Answer 45

b) it decreases condenser capacity

Question 46

Which of the following statements about Manual Purging Systems is false?

a) They must be operated on a regular schedule.
b) The receiver and condenser should be purged separately.
c) Purging rids the system of noncondensable gases.
d) Refrigerant vapour in the purger is always expelled with the noncondensable gases.
e) Gas being vented into the atmosphere must pass through a water beaker.

Answer 46

d) Refrigerant vapour in the purger is always expelled with the noncondensable gases.

Question 47

The chilling coil in an automatic purger has a primary
function to:
a) lower the operating temperature of the purger
b) keep the system cooling while being purged
c) increase the efficiency of the system
d) keep discharge through the coil at the lowest available suction pressure
e) separate refrigerant vapour from the noncondensable gases to be purged

Answer 47

e) separate refrigerant vapour from the noncondensable gases to be purged

Question 48

When using lighted sulphur candles to test for ammonia leaks in a refrigeration system, the presence of ammonia will be indicated by:

a) a cloud of yellow smoke
b) light brown smoke
c) heavy white smoke
d) heavy black smoke
e) light red smoke

Answer 48

c) heavy white smoke

Question 49

Leak testing for tightness under pressure of a refrigeration system:

a) is done by the manufacturer
b) is done with oxygen
c) is done with ammonia
d) is done with an inert gas
e) is done with softened water

Answer 49

d) is done with an inert gas

Question 50

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 50

c) is done with a sulphur candle for ammonia

Question 51

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 51

d) Open the liquid line shut-off valve.

Question 52

A sulphur candle is a test for:

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

Answer 52

b) ammonia leaks

Question 53

Before charging a system which of the following needs to be done?

a) Interlocks need to be tested
b) Controls need to be set
c) Controls need to be set
d) Required valves need to be opened
e) All of the above

Answer 53

e) All of the above

Question 54

The initial refrigerant charge is given where on the system?

a) The high side of the system
b) The low side of the system
c) The evaporator
d) The expansion valve
e) The heat exchanger

Answer 54

a) The high side of the system

Question 55

Frost formation on the suction line indicates what?

a) Moisture in the system
b) “Copper-Plating” on the bearings and compressor exhaust valve
c) Overcharging the system
d) Thermostat controlled solenoid deterioration
e) Inadequate levels of refrigerant in the system

Answer 55

c) Overcharging the system

Question 56

The liquid line shutoff valve is:

a) used when purging the system
b) a regulating valve
c) used to relieve pressure
d) required to be closed when charging the system
e) on top of the receiver

Answer 56

d) required to be closed when charging the system

Question 57

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 57

b) is done by adding refrigerant between the liquid shutoff valve and the expansion valve

Question 58

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 58

e) should be done with the liquid line shutoff valve closed

Question 59

When initially charging a refrigeration system

a) it must be done with the liquid line shutoff valve open:
b) it is done with a liquid refrigerant
c) it must be done after the unit is shut down
d) it must be done at the compressor suction
e) water should be added to dilute the refrigerant

Answer 59

b) it is done with a liquid refrigerant

Question 60

What can cause a high discharge pressure with refrigeration systems?

a) low evaporator level
b) too much cooling water to the condenser
c) over-purging the unit
d) when unit runs continuously
e) unit over-charged with refrigerant

Answer 60

e) unit over-charged with refrigerant

Question 61

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 repressurized after the oil has been added.
e) None of the above

Answer 61

a) Oil is added by charging it into the crankcase.

Question 62

It is very important to open oil drain valves and plugs in the crankcase for which of the following reasons?
a) The oil is very hot.
b) The oil is very cold.
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) Oil can never be drained below the critical minimum
level.

Answer 62

c) Residual pressure in the crankcase may blow refrigerant vapour and oil out

Question 63

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 63

b) is done with a vacuum on the crankcase

Question 64

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 64

d) Valves in lines connecting suction gages should be

closed

Question 65

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) Fill the compressor with liquid refrigerant
c) Fill the evaporator with refrigerant vapour
d) Open all the suction valves on the connecting condenser line
e) Discharge all the condenser refrigerant into the
evaporator

Answer 65

a) Pump down the evaporator

Question 66

Which of the following steps is NOT part of the startup
procedure of centrifugal compressor refrigerating systems.
a) Check the refrigerant levels.
b) Open the stop valves in the chilled water system.
c) Open the main circuit breakers.
d) Open the makeup water valve.
e) Operate the oil pump for at least 10 minutes before
starting the compressor

Answer 66

c) Open the main circuit breakers.

Question 67

A centrifugal compressor refrigerating system can be stopped simply by pressing the stop button unless which of the following circumstances is true?
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) None of the above

Answer 67

b) The system’s auxiliary equipment is not electrically

interlocked.

Question 68

The safety control in a centrifugal compressor which ensures the compressor to only be started under a no-load condition is called

a) low oil pressure cutout switch
b) condenser high pressure cutout
c) chilled water flow switch
d) motor demand limiter
e) vane closed switch

Answer 68

e) vane closed switch

Question 69

If a compressor fails to start but the motor is running,
which of the following could be a cause?
a) The control circuit is open
b) The compressor is seized
c) The coupling is sheared or broken
d) The motor is burned out
e) The starter is defective

Answer 69

c) The coupling is sheared or broken

Question 70

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:

a) preventative maintenance
b) safety controls
c) routing operation
d) regular maintenance
e) none of the above

Answer 70

a) preventative maintenance

Question 71

Checking the condition of electrical starters and contactors is categorised under which of the following maintenance schedules?

a) Daily maintenance
b) Weekly maintenance
c) Monthly maintenance
d) Semi-annual Maintenance
e) Annual maintenance

Answer 71

e) Annual maintenance

Question 72

In an Ammonia Absorption System what is used as the
absorbent?
a) Ammonia
b) Air
c) Lithium Bromide
d) Water
e) Freon

Answer 72

d) Wate

Question 73

Which of the following is not found on the low side of an ammonia system?

a) Evaporator
b) Generator
c) Absorber
d) Cooling water
e) Low pressure ammonia vapour

Answer 73

b) Generator

Question 74

Ammonia systems are seldom used for air conditioning purposes in large buildings mainly because:

a) ammonia systems require too much maintenance
b) ammonia systems are too expensive
c) ammonia is too toxic
d) ammonia does not provide sufficient cooling power for large operations
e) ammonia systems require a separate power supply not available in most large buildings

Answer 74

c) ammonia is too toxic

Question 75

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

a) Pumps in absorption systems require more electrical power.
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) Slugs of liquid carried over from the evaporator do not damage the compression system but can ruin an absorption system.

Answer 75

c) Cooling water requirements are larger for an absorption system than for a compression system.

Question 76

In a Lithium Bromide System which of the following is the refrigerant?

a) Lithium Bromide
b) Ammonia
c) Freon-22
d) Water
e) None of the above

Answer 76

d) Water

Question 77

In order to lower the boiling point of the refrigerant it is important that the system maintain:

a) an extremely high vacuum
b) very high pressure
c) very low temperatures
d) very fast refrigerant flow
e) high absorbent circulation

Answer 77

a) an extremely high vacuum

Question 78

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

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

Answer 78

d) As water vapour is absorbed by the Lithium Bromide the vacuum decreases.

Question 79

The absorber is equipped with a pump for which of the following reasons?

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

Answer 79

d) To speed the absorption of water vapour

Question 80

What is the function of the concentrator (generator)?

a) To cool the refrigerant vapour
b) To increase the absorbency potential of used LithiumBromide
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 80

b) To increase the absorbency potential of used LithiumBromide

Question 81

Most absorbency 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 maintain the continuous vacuum
c) To decrease the evaporation point of the refrigerant
d) To run the pumps which force the water through the
sprayers
e) To evaporate the water out of the weak Lithium Bromide

Answer 81

e) To evaporate the water out of the weak Lithium Bromide

Question 82

This occurs when the temperature of a strong but still
unsaturated solution is lowered so far that its salt
concentration exceeds the maximum concentration possible at the lower temperature.
a) Ionization
b) Dissociation
c) Crystallization
d) Vapourization
e) Neutralization

Answer 82

c) Crystallization

Question 83

When the temperature of a solution increases, which of the following statements is true?

a) The vapour pressure is high
b) Less water molecules leave the solution
c) The solubility of the salt decreases
d) The concentration decreases
e) The equilibrium constant decreases

Answer 83

a) The vapour pressure is high

Question 84

The concentration of Lithium Bromide in an absorption
refrigerating system will change during which of the
following steps?
a) Going through the expansion valve
b) Going through the suction valve
c) Cooling through the heat exchanger
d) Absorbing water vapour in the absorber
e) None of the above

Answer 84

d) Absorbing water vapour in the absorber

Question 85

Concentration of the Lithium Bromide can be most easily controlled by which of the following means?
a) Controlling the volume of water sprayed into the
absorber.
b) Controlling the temperature in the cooling tower.
c) Controlling the amount of weak Lithium Bromide pumped into the generator.
d) Controlling the pressure in the vacuum between the
evaporator and the absorber.
e) Controlling the temperature in the generator

Answer 85

e) Controlling the temperature in the generator

Question 86

Which of the following is NOT a result of having
noncondensable gases in the absorption systems?
a) Corrosion
b) Oxidation of Lithium Bromide
c) Lower than normal temperatures of the chilled water
leaving the evaporator
d) Reduction in capacity of the system
e) Crystallization in the heat exchanger

Answer 86

c) Lower than normal temperatures of the chilled water

leaving the evaporator

Question 87

Which of the following are elements of a mechanical purging
system?
i) purge pickup tube
ii) purge chamber
iii) manual shutoff valve
iv) safety solenoid valve
v) oil trap
vi) vacuum pump
a) i and ii only
b) i, ii, and v only
c) iv and vi only
d) i, iii, and v only
Which of the following are elements of a mechanical purging
system?
i) purge pickup tube
ii) purge chamber
iii) manual shutoff valve
iv) safety solenoid valve
v) oil trap
vi) vacuum pump
a) i and ii only
b) i, ii, and v only
c) iv and vi only
d) i, iii, and v only
e) all of the elements

Answer 87

e) all of the elements

Question 88

Which of the following is not a step in the seasonal prestart service?

a) clean all cooling and chilled water strainers
b) add water treatment chemicals
c) turn on energy sources
d) check the purge pump
e) check the magnetic strainers

Answer 88

c) turn on energy sources

Question 89

During seasonal startup, when should the purge pump be started?

a) Simultaneously with the absorption unit
b) One half hour before the absorption unit is started
c) At least 24 hours after the compressor is started
d) About one half hour after the absorption unit is started
e) Only when noncondensables are detected in the system

Answer 89

d) About one half hour after the absorption unit is started

Question 90

When shutting down the refrigeration system for a weekend or less which of the following is a correct shutdown procedure?

a) Drain the cooling water circuit
b) Close the manual steam or hot water supply valve
c) Service the purge pump
d) Open all disconnect switches
e) Turn off the air supply to the pneumatic control system

Answer 90

b) Close the manual steam or hot water supply valve

Question 91

If there is a crystallization upon shutdown a possible
corrective action is to:
a) add octyl alcohol charge
b) purge the system
c) adjust cooling tower control
d) check pump operation
e) reduce steam pressure

Answer 91

d) check pump operation