4B Older practice Questions Refrigeration Flashcards
(204 cards)
1
Q
Which of the following are principal parts in a closed cycle compression refrigeration system? 1. Absorber 2. Evaporator 3. Compressor 4. Condenser a. 1, 2 b. 3 c. 1, 2, 4 d. 2, 3, 4 e. 1, 2, 3.
A
d. 2, 3, 4
2
Q
Which of the following is not a component of the low, pressure side
of the system?
a. Compressor discharge
b. The evaporator
c. The downstream side of the regulating valve
d. Compressor inlet
e. The accumulator.
A
a. Compressor discharge
3
Q
Which of the following statements about a system that circulates
warm brine back to a chiller tank 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.
A
d. The evaporator cools the brine.
4
Q
The primary difference between direct and indirect refrigeration systems is the: a. Type of heat transfer medium b. Type of refrigerant c. Evaporator pressure d. Compressor location e. Location of the medium being cooled.
A
e. Location of the medium being cooled.
5
Q
The heat given up by the brine in the evaporator, must equal the heat: a. Picked up by the receiver b. Produced by the compressor c. Given up by the condenser d. Gained by the condenser e. Picked up by the refrigerant.
A
e. Picked up by the refrigerant.
6
Q
Which of the following is a result of an economiser on the
refrigeration system.
a. An intercooling effect on the compressor.
b. The reduction of the power required for compression of the
refrigerant.
c. The reduction of flash vapour in the evaporator.
d. An increase in the refrigerating capacity of a system.
e. All of the above.
A
e. All of the above.
7
Q
The brine pump:
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.
A
c. Circulates the brine through the cooling circuits
8
Q
For a direct expansion 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 at temperature 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.
A
d. The evaporator can be located in air circulating ducts
communicating with the material or space being refrigerated
9
Q
Refrigerant condensers:
a. Are always water cooled.
b. Cool the gas refrigerant discharged from the compressor
c. Have a safety valve
d. Remove sensible heat only from the refrigerant
e. Are not required for Freon type refrigerants.
A
b. Cool the gas refrigerant discharged from the compressor
10
Q
A purpose of a liquid refrigerant control or regulating 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. Isolate the high side from the low side.
A
e. Isolate the high side from the low side.
11
Q
Which of the following statements about the economisers is false?
a. It controls the flow of liquid refrigerant from the low, pressure
evaporator to the high, pressure 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 economiser float chamber is connected via the motor to
the second stage inlet of the compressor.
e. It is composed of two chambers.
A
a. It controls the flow of liquid refrigerant from the low, pressure
evaporator to the high, pressure condenser
12
Q
The purpose of the condenser in an ammonia compression refrigeration system is to: a. Establish two pressure levels b. Extract heat from the system c. Absorb heat into the system d. Regulate the flow of refrigerant e. Reheat the refrigerant.
A
b. Extract heat from the system
13
Q
Raising the condensing point (saturation temperature) of the refrigerant vapour above the temperature of the cooling medium is the function of the: a. Compressor b. Condenser c. Evaporator d. Absorber e. Refrigerant.
A
a. Compressor
14
Q
A compression refrigeration system can be divided into two parts; a
high, pressure section carrying the head pressure and a low,
pressure section carrying the _____ pressure:
a. Discharge
b. Back
c. Hot
d. Return
e. Suction.
A
e. Suction.
15
Q
In the condenser:
a. Latent heat must be restored to the refrigerant.
b. The surrounding medium must be hotter than the refrigerant.
c. The heat in the refrigerant lost in the evaporator must be
restored.
d. The condensing medium absorbs heat from the refrigerant.
e. The time to cool a product is condensed.
A
d. The condensing medium absorbs heat from the refrigerant.
16
Q
In actual systems there will be a gradual pressure drop through
each side of the system due to:
a. the economiser
b. Friction in the evaporator, condenser, and piping
c. Decomposition of refrigerants
d. Coefficients of expansion of system components
e. Superheating effects.
A
b. Friction in the evaporator, condenser, and piping
17
Q
Which of the following is not an advantage of a factory assembled
packaged refrigerant?
a. Components are designed to match each other
b. Parts can be ordered and installed separately
c. The unit is equipped with all the required auxiliary equipment
d. Space requirements are minimised
e. The unit is more compact.
A
b. Parts can be ordered and installed separately
18
Q
The type of brine used for skating and hockey rink refrigeration systems is usually: a. Calcium sulphate b. Calcium chloride c. Calcium carbide d. Calcium nitrate e. Sodium chloride.
A
b. Calcium chloride
19
Q
In the evaporator:
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.
A
c. The refrigerant absorbs heat from the surrounding medium
20
Q
A controlled amount of high temperature, high temperature
liquid refrigerant:
5
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. Refrigerant flow is not controlled.
e. Occurs in isoenthalpic systems.
A
a. Passes through the regulating valve to the evaporator.
21
Q
Refrigerant evaporators:
a. Always have 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.
A
e. Are usually oil cooled.
22
Q
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.
A
c. Depends on pressure in the evaporator
23
Q
Piston displacement 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.
A
c. Volume of refrigerant that can be circulated through all the
cylinders per unit time
24
Q
Which of the below is the compressor responsible for doing?
- Maintains a high pressure in the condenser
- Maintains a low pressure in the evaporator
- Raises the pressure of the refrigerant
a. 1
b. 1, 3
c. 2, 3
d. 3
e. 1, 2, 3.
A
e. 1, 2, 3.
25
A typical stationary crankshaft seal consisting of a metallic bellows
soldered at one end to a ring (seal nose) which bears either against
a shoulder on the shaft or against a seal ring on the shaft is called a:
a. Packing gland seal
b. Diaphragm seal
c. Bellows seal
d. Rotating Mechanical seal
e. Set screw.
c. Bellows seal
26
For a Helical Rotor Design rotary 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. All of the above.
b. The driving rotor has less helical lobes than the driven rotor
has flutes
27
Refrigerant compressors:
a. Must have intercoolers
b. Could be centrifugal type
c. Are of the positive displacement type only
d. Are used with vapour absorption systems only
e. Discharge directly into the evaporator.
b. Could be centrifugal type
28
Refrigeration compressors:
a. Raise the refrigerant vapour pressure
b. Must have water jackets
c. Must be placed outside the building
d. Raise the vapour pressure on the discharge of the evaporator
e. Increase the vacuum in the receiver.
a. Raise the refrigerant vapour pressure
29
Which of the following is not a function of the compressor in a
refrigeration system?
a. To draw low pressure refrigerant out of the evaporator
b. To draw low temperature refrigerant out of the evaporator.
c. To lower the temperature of the refrigerant
d. To maintain sufficiently low pressure in the evaporator
e. To raise the pressure of the refrigerant.
c. To lower the temperature of the refrigerant
30
In a rotating vane design rotary compressor, a good seal is
maintained between the vanes and the cylinder by:
a. Centrifugal force
b. The oil
c. High pressure refrigerant vapour
d. Low pressure suction
e. The eccentric rotor size.
a. Centrifugal force
31
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.
a. Establish two pressure levels
32
In rotating mechanical seals the sealing ring is held in position by:
a. A nut bolt and washer
b. Centrifugal force
c. Oil suction
d. High pressure refrigerant vapour
e. A spring.
e. A spring.
33
One negative factor of Hermetic Type reciprocating compressors is:
a. Compressor and motor are mounted within the same housing
b. The motor is cooled by the low pressure, low temperature
vapour drawn into the housing
c. Need not have or require shaft sealing
d. Field servicing is not possible
e. The compressor is driven by an electric motor.
d. Field servicing is not possible
34
```
Pistons and connecting rods are found in which of the following
types of compressors?
a. Reciprocating
b. Rotary
c. Centrifugal
d. Rotary and centrifugal
e. Reciprocating and centrifugal.
```
a. Reciprocating
35
```
Which of the following three compressor types uses impellers to
draw in vapour?
a. Centrifugal compressors
b. Rotary compressors
c. Reciprocating Compressors
d. None of the above
e. All of the above.
```
a. Centrifugal compressors
36
```
Rotary compressors have several different designs, some of which
are:
1. Stationary blade
2. Rotary lobe
3. Helical rotor
4. Rotating blade
5. Reciprocating piston
a. 1, 2, 3
b. 2, 3, 4
c. 3, 4, 5
d. 1, 3, 4
e. 1, 3, 5.
```
d. 1, 3, 4
37
The safety head of a refrigeration compressor is designed to:
a. Relieve high-pressure gas compression
b. Pop when the pressure is too high
c. Relieve pressure due to liquid in the cylinder
d. Prevent explosion damage
e. Operate in place of a safety relief valve.
c. Relieve pressure due to liquid in the cylinder
38
The three main classifications of refrigeration compressors are:
1. Reciprocating
2. Axial
3. Centrifugal
4. Rotary
5. Turbo
a. 1, 2, 3
b. 2, 3, 4
c. 3, 4, 5
d. 1, 3, 4
e. 1, 3, 5.
d. 1, 3, 4
39
```
Refrigeration compressor mechanical seals have the following
advantages over packing glands.
1. They are less costly
2. They require less maintenance
3. There is less wear on rotating shafts
4. The leakage helps with lubrication and cooling
a. 1, 2
b. 2, 3
c. 3, 4
d. 1, 3
e. 2, 4.
```
b. 2, 3
40
The compression ratio of a refrigeration compressor can be
calculated by:
a. Dividing the absolute discharge pressure by the inlet pressure
b. Dividing the discharge pressure by the inlet pressure
c. Dividing the absolute inlet pressure by the absolute discharge
pressure
d. Dividing the inlet pressure by the discharge pressure
e. Dividing the absolute discharge pressure by the absolute inlet
pressure.
e. Dividing the absolute discharge pressure by the absolute inlet
pressure.
41
Which of the following characteristics is common in all of the group B refrigerants?
a. High toxicity
b. High flammability
c. Average Flammability
d. Low Toxicity
e. Low flammability.
a. High toxicity
42
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. Equal to its specific volume.
a. Equal to its latent heat of vaporization
43
Which of the following is not a physical property of refrigerants
a. Toxicity
b. Odour
c. Leakage tendency
d. Oxidization
e. Explosiveness.
d. Oxidization
44
R-22 (Freon-22) is non-toxic and non-flammable. Which of the following groups does it belong to?
a. Group A2
b. Group B4
c. Group A1
d. Group A3
e. Group B2.
c. Group A1
45
The ability of a refrigerant to be dissolved into oil and vice versa is called:
a. Moisture reaction
b. Enthalpy
c. Density
d. Leakage tendency
e. Miscibility.
e. Miscibility.
46
```
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. Freon-22
c. Sulphur Dioxide
d. Butane
e. Propane.
```
b. Freon-22
47
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
b. 30°C condensing and –15°C evaporating
48
Common commercial air conditioning systems use one of the following as the refrigerant:
a. Methyl chloride
b. Ammonia
c. Methane
d. Freon
e. Carbon dioxide.
d. Freon
49
Ammonia is the only commonly used refrigerant that has the physical property of:
a. Miscibility
b. Enthalpy
c. Flammability
d. Density
e. Low condensing pressure.
c. Flammability
50
The property which has to be known for the calculation of the size of control valves and piping etc, is:
a. Specific gravity
b. Enthalpy
c. Refrigerating effect
d. Density
e. Boiling point.
d. Density
51
```
A refrigerant in the “B” Group that is used more than others in its group in refrigeration systems is:
3
a. Propane
b. Ammonia
c. Freon 12
d. Freon 22
e. Methane.
```
b. Ammonia
52
Molecular mass is a dependent factor in which of the following physical properties?
a. Miscibility
b. Leakage tendency
c. Toxicity
d. Flammability
e. Explosiveness.
b. Leakage tendency
53
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.
b. 335 kJ per kg
54
Freon:
a. Is non-toxic
b. Has a strong odor
c. Is explosive when mixed with air
d. Is highly toxic
e. Is prohibited as a refrigerant
a. Is non-toxic
55
The refrigerant R-11 belongs to the following group:
a. “A2”
b. “B1”
c. “A3”
d. “2B”
e. “A1”.
e. “A1”.
56
Which of the following is not a thermodynamic property of heat?
a. Entropy
b. Enthalpy
c. Density
d. Volume
e. Miscibility.
e. Miscibility.
57
The refrigerant with the highest refrigerating effect per kg of any refrigerant is:
a. Propane
b. Ammonia
c. Carbon dioxide
d. Freon 22
e. Water.
b. Ammonia
58
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 systems.
d. Are well suited for industrial refrigeration
59
The ideal commercial 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 the least costly.
d. Be environmentally friendly
60
Freon 22 refrigerant is:
a. Not miscible with oil
b. Mostly used in packing plants
c. Corrosive on copper
d. Corrosive on aluminium
e. A heat, transferring medium
e. A heat, transferring medium.
61
Which of the following has the highest boiling point?
a. Ammonia
b. Freon 12
c. Freon 22
d. Freon 113
e. Water.
e. Water.
62
Group “A” refrigerants as found in the current code are:
a. Non-flammable
b. Low-flammable
c. Low-toxic
d. Low-toxic and flammable
e. High-toxic and flammable.
c. Low-toxic
63
Which of the following is not a requirement for an ideal refrigerant?
a. A fairly low condensing pressure
b. Light in weight
c. A low boiling point
d. A non-poisonous nature
e. A non-corrosive action on metals
b. Light in weight
64
The amount of heat given up by a refrigerant to the evaporator is equal to:
a. The difference between the head pressure and the system pressure times the mass in kg
b. Its latent heat of fusion
c. Its latent heat of vaporization minus the heat required to flash the liquid due to the pressure drop
d. Its latent heat of fusion minus the heat required to flash the liquid due to the pressure drop
e. Its latent heat of vaporization.
c. Its latent heat of vaporization minus the heat required to flash the liquid due to the pressure drop
65
Which of the following is not a physical property of a refrigerant?
a. Miscibility
b. Leakage tendency
c. Toxicity
d. Flammability
e. Entropy.
e. Entropy.
66
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
c. Water evaporating requires a large amount of latent heat
67
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. A multi coil evaporator
d. All of the above
e. None of the above
a. Dry evaporator
68
Which of the following statements about the shell and tube evaporator type is false?
a. It is also known as a chiller.
b. The liquid to be cooled circulates through the tubes in the direct-expansion operation.
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. This type of evaporator cools mainly liquids.
b. The liquid to be cooled circulates through the tubes in the direct-expansion operation.
69
Which of the following statements about double tube condensers is true?
a. Consists of two separate tubes side by side
b. Cannot be used with air, cooled condensers
c. Water flows in the inner tube in the opposite direction of the flow of refrigerant
d. Has the highest efficiency of the water-cooled condensers
e. Has a small condenser for a large capacity system.
c. Water flows in the inner tube in the opposite direction of the flow of refrigerant
70
The evaporator that increases heat exchange by crimping thin metal plates to its form is which type of evaporator?
a. Plate surface evaporator
b. Bare tube evaporator
c. Shell and tube evaporator
d. Finned tube evaporator
e. Double tube.
d. Finned tube evaporator
71
The common types of water cooled condensers used in refrigeration systems are the:
1. Shell and tube
2. Shell and coil
3. Double tube
4. Plate surface
a. 1, 2, 3
b. 1, 3, 4
c. 2, 3, 4
d. 1, 2, 4
e. 3, 4.
a. 1, 2, 3
72
An evaporator that can easily be cleaned and defrosted manually without interrupting the cooling process is which type of evaporator?
a. Bare finned evaporator
b. Finned evaporator
c. Plate surface evaporator
d. Shell and tube evaporator
e. None of the above
c. Plate surface evaporator
73
The condenser which is very expensive to clean which requires the tubes to be cleaned with acid and neutralised is the:
a. Shell and tube condenser
b. Shell and coil condenser
c. Double tube condenser
d. Evaporative condensers
e. Baffle condensers
b. Shell and coil condenser
74
Refrigerant condensers:
a. Are always water, cooled
b. Cool the liquid refrigerant from the compressor
c. Cool the hot compressed refrigerant vapour until it condenses to a liquid
d. Remove the sensible heat from the gas
e. Produce a vacuum in the receiver
c. Cool the hot compressed refrigerant vapour until it condenses to a liquid
75
```
According to their construction evaporators may be divided into the following classes.
3
1. Dry
2. Bare tube
3. Plate surface
4. Flooded
5. Direct expansion
6. Finned tube
7. Shell and tube
a. 1, 2, 3, 4
b. 2, 3, 4, 5
c. 3, 4, 5, 6
d. 4, 5, 6, 7
e. 2, 3, 6, 7.
```
e. 2, 3, 6, 7.
76
The two types of evaporators, dry evaporators and flooded evaporator differ principally in what respect?
a. The dry evaporator cannot cool liquids
b. The method of refrigerant circulation
c. The type of refrigerant used
d. The size of the evaporator
e. The field maintenance availability of the types
b. The method of refrigerant circulation
77
The amount of heat absorbed by evaporating water is:
a. 99.63 kJ/kg
b. 335 kJ/kg
c. 417.46 kJ/kg
d. 2258 kJ/kg
e. 2675.5 kJ/kg.
d. 2258 kJ/kg
78
Refrigerant evaporators are:
a. Only used in ammonia systems
b. Part of the high side of the system
c. Used to transfer oil
d. Only used with very high pressure refrigeration systems
e. Used to transfer heat.
e. Used to transfer heat.
79
The purpose of the condenser in a refrigeration system is to:
a. Remove the sensible heat from the refrigerant
b. Remove the latent heat from the refrigerant
c. Cool the liquid refrigerant
d. Vaporise the liquid refrigerant
e. Reduce the pressure in the evaporator
b. Remove the latent heat from the refrigerant
80
Based on operation the two basic types of evaporators are the dry and _____ evaporator.
a. Direct expansion
b. Bare tube
c. Plate surface
d. Flooded
e. Finned tube.
d. Flooded
81
Defective condenser operation is a result of the presence of all of the following except:
a. Scale forming chemicals
b. Dirty cooling water
c. Non-condensable gases
d. Low coolant circulation
e. Loss of refrigerant.
e. Loss of refrigerant.
82
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. Mechanical rooms.
a. Roof tops
83
The current 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
c. 10 kg
84
Which of the following statements about pressurestats 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.
c. A pressurestat can be used in conjunction with an automatic expansion valve
85
Which of the following actuating control valves is electro magnetically operated?
a. Thermostat valve
b. Fluid expansion regulator valve
c. Evaporator pressure regulating valve
d. Condenser cooling water regulating valve
e. Solenoid valve.
e. Solenoid valve
86
Oil pressure failure switches are used to perform which of the following functions?
a. To keep the oil pressure at a level where the oil will not freeze.
b. To prevent compressor start-up if the oil heater fails.
c. To separate refrigerant dissolved in the oil from the lubricant.
d. To shut down the compressor when the oil pressure drops below the minimum.
e. To keep to oil from freezing at low pressure
d. To shut down the compressor when the oil pressure drops below the minimum
87
5. Actuating or secondary controls are used to:
a. Indirectly control changes in operation
b. Regulate the refrigeration system output when the system limits are reached
c. Regulate the refrigeration system output when the system limits are exceeded
d. Control the operation of cooling water
e. Protect the system from operation beyond set limits.
a. Indirectly control changes in operation
88
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, not air flow
e. They can be used to close flow indicator circuits.
d. They can only be used to regulate liquid flow, not air flow
89
Limiting or safety controls are used to:
a. Indirectly control changes in operation
b. Regulate the refrigeration system output when the system limits are reached
c. Regulate the refrigeration system output when the system limits are exceeded
d. Control the operation of cooling water
e. Protect the system from operation beyond set limits
e. Protect the system from operation beyond set limits.
90
With regard to the high, pressure side, the maximum setting for a pressure, limiting device on a refrigeration system shall not exceed the pressure relief device by:
a. 100%
b. 75%
c. 90%
d. 80%
e. 50%.
c. 90%
91
Operating or primary controls are used to:
a. Indirectly control changes in operation
b. Regulate the refrigeration system output when the system limits are reached
c. Regulate the refrigeration system output when the system limits are exceeded
d. Control the operation of cooling water
e. Protect the system from operation beyond set limits.
b. Regulate the refrigeration system output when the system limits are reached
92
Safety controls serve what function?
a. They stop operation when 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.
e. All of the above.
93
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
a. Frosting of coils
94
Expansion valves:
a. Will expand the liquid to the receiver
b. Relieve high pressure in the receiver
c. Regulate the liquid refrigerant flow to the evaporator
d. Are used to charge the refrigeration system
e. Isolate the compressor from the condenser
c. Regulate the liquid refrigerant flow to the evaporator
95
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.
d. Temperature actuated control
96
The operating control which consists of a hydroscopic element made of material similar to multiple strands of human hair is called a:
a. Humidistat
b. Thermostat
c. Fluid expansion regulator
d. Pressurestat
e. Bimetal element.
a. Humidistat
97
The oil pressure failure switch uses a _____ element.
a. Fluid expansion
b. Bimetallic
c. Thermostatic
d. Humidity activated
e. Volumetric.
b. Bimetallic
98
The safety control that 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 cut out.
c. Motor overload protection
99
Starting, stopping or unloading of the compressor is usually done by all of the following operating controls except:
a. Temperature actuated control.
b. A viscosity activated control.
c. A pressure activated control.
d. A humidity activated control.
e. All of the above can control the compressor
b. A viscosity activated control.
100
18. A bimetallic element converts temperature changes to mechanical motion by having metals of different:
a. Coefficients of linear expansion
b. Rates of temperature change
c. Temperatures
d. Coefficients of thermal conductivity
e. Electron velocities.
a. Coefficients of linear expansion
101
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 un-loader
c. Variable Inlet Guide Vanes
102
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.
a. Thermostatic expansion valve
103
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. Dampering
c. Suction throttling
d. Cylinder Bypass
e. Sectional evaporating
d. Cylinder Bypass
104
The type of operation that 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
a. Intermittent operation
105
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. The control may be used with multiple cooling coils connected to the same compressor.
c. A spring exerting a downward force on the diaphragm tends to open the valve.
d. The spring force is counter acted by the evaporator pressure acting upward against the diaphragm that closes the valve.
e. When the compressor stops the valve automatically shuts off.
b. The control may be used with multiple cooling coils connected to the same compressor.
106
Sectional evaporators control the capacity of the evaporator by which of the following means? By:
a. Varying the quantity of air being cooled passing over the evaporator coils
b. Intermittent operation of the compressor
c. Divided multi-part evaporators which have refrigerant control valves which can be shut off independently as the load decreases
d. Switching gear in the compressor
e. Decreasing suction in the compressor
c. Divided multi-part evaporators which have refrigerant control valves which can be shut off independently as the load decreases
107
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 device’s 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
d. A capillary tube
108
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. The quantity of air passing through the duct depends on the damper position.
d. Multi-speed blowers cannot be used in combination with evaporator dampers.
e. Actuators are required to provide damper movement.
e. Actuators are required to provide damper movement
109
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
a. The volumetric expansion of a fluid against a return spring
110
Which control is used to maintain a constant level of liquid refrigerant in a flooded evaporator in the liquid reserve tank?
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.
c. A low-pressure float valve
111
The two most commonly used methods of reciprocating compressor output control are:
1. Intermittent operation
2. Cylinder unloaders
3. Cylinder bypass
4. Continuous operation
a. 1, 2
b. 1, 4
c. 2, 3
d. 3, 4
e. 2, 4.
b. 1, 4
112
Manual or hand operated expansion valves are seldom used in modern refrigeration systems except for 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
b. In the bypass line around the automatic control valve
113
The automatic 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
e. Evaporator pressure against a return spring.
114
What will be the effect if an insufficient amount of 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 vapor 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 freeze in position.
b. The heat in the vapor leaving the evaporator causes the pressure in the thermal element to increase opening the expansion valve
115
Which of the following are refrigeration metering or flow control devices?
1. Orifice meter
2. Automatic expansion valve
3. Bourdon tube
4. Thermostat
5. Low-pressure float
6. Capillary tube
a. 1, 2, 3
b. 3, 4, 5
c. 2, 5, 6
d. 4, 5, 6
e. 2, 4, 6.
c. 2, 5, 6
116
In a system controlled by a high-pressure float valve excessive liquid will cause which of the following:
a. Liquid to be carried over to the compressor with the vapor
b. The float chamber to become vapor locked
c. Water hammer
d. Automatic system shut down
e. The compressor to rum continuously.
a. Liquid to be carried over to the compressor with the vapor
117
The reason for using a weighted valve pin in a high-pressure float valve system is:
a. To get proper pressure drop into the evaporator
b. To reduce frosting of the line immediately after the float valve
c. To allow the room temperature to be adjusted
d. Act as a pressure relief device
e. To prevent flooding of the evaporator.
b. To reduce frosting of the line immediately after the float valve
118
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 compressor’s pressure
c. Liquid being carried over to the compressor with the vapour
d. Starving the evaporator and reducing the capacity of the system
e. The compressor will run continuously
Starving the evaporator and reducing the capacity of the system
119
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. Glued.
b. Screwed
120
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. 20%
d. 25%
e. 50%.
a. 10%
121
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
a. Lower noise levels
122
Which of the following statements about refrigeration 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. Pressure gage will not work if the system is equipped with pulsation dampeners
e. Permanently installed pressure gages shall be constructed for at least 1.5 times the design pressure
a. They indicate pressures and corresponding temperatures in a system.
123
5. 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
d. An accumulator
124
A direct expansion type evaporator that has more than one (1) refrigerant circuit in it requires what to have even refrigerant flow in each circuit?
a. A stop valve
b. An expansion valve
c. A distributor
d. A purge valve
e. A thermal regulator
c. A distributor
125
The accessory that maintains efficient heat transfer by collecting oil that coats the tubes of the condenser is called:
a. Strainer
b. A strainer-drier
c. An oil scrubber
d. A filter
e. An oil separator
e. An oil separator.
126
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.
b. Piping must be disconnected to clean the strainer
127
As per current code a pressure gage, when permanently installed on the high side of a refrigeration system, shall be constructed for at least _____ times the design pressure.
a. 1
b. 1.1
c. 1.2
d. 1.5
e. 2.
c. 1.2
128
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.
d. Dangerously high system pressures
129
As per current code stop valves used with soft, annealed copper tubing or hard drawn copper tubing _____ in outside diameter or smaller shall be securely mounted, independent of tubing fastenings or supports.
a. 15 mm
b. 20 mm
c. 22 mm
d. 25 mm
e. 50 mm.
c. 22 mm
130
As per current code refrigerant discharge to atmosphere shall not be less _____ above the adjoining ground level.
a. 4 m
b. 4.6 m
c. 5 m
d. 10 m
e. 15 m.
b. 4.6 m
131
As per current code refrigerant discharge to atmosphere shall not be less _____ from any window, ventilation opening or exit in any building.
a. 4 m
b. 4.6 m
c. 6.5 m
d. 7.6 m
e. 10 m.
d. 7.6 m
132
As per current code all refrigeration systems containing more than 3 kg of refrigerant shall have stop valves installed at the following locations except the:
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.
e. Suction inlet of each liquid receiver.
133
The emergency discharge line in a refrigeration system:
a. Is located only on the condenser
b. Should have a emergency valve outside the building
c. Is required on all sizes of refrigeration systems
d. Is located on the evaporator
e. Is a vented sewer line.
b. Should have a emergency valve outside the building
134
Moisture in a system can result in which of the following:
a. The formation of ice
b. Acid formation
c. Corrosion
d. The deterioration of motor insulation
e. All of the above.
e. All of the above
135
A chemical dot placed under the glass lens of a sight glass that is exposed to the liquid serves what function? To monitor:
a. Liquid flow
b. Refrigerant levels
c. The presence of moisture
d. The presence of foreign particles
e. The pressure levels
c. The presence of moisture
136
Ammonia leaks may be traced with a wetted test paper treated with:
a. Caustic soda
b. Potassium chromate indicating liquid
c. Potassium iodide-iodate
d. Litmus solution
e. Sulphuric acid
d. Litmus solution
137
A sulphur candle is a test for what:
a. Freon leaks
b. Ammonia leaks
c. Air leaks
d. Vacuum seal
e. CFC leaks
b. Ammonia leaks
138
Before charging a system which of the following needs to be done?
a. The interlocks need to be tested
b. The sequence of controls must be tested
c. The controls need to be set
d. The required valves need to be opened
e. All of the above
e. All of the above.
139
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
a. The high side of the system
140
Which of the following statements about Manual Purging Systems 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. Refrigerant vapour in the purger is always expelled with the non-condensable gases.
e. They must be operated on a regular schedule.
d. Refrigerant vapour in the purger is always expelled with the non-condensable gases
141
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.
b. It is done with a liquid refrigerant
142
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 over stresses compressor parts
e. It is detrimental to compressor lubrication.
b. It decreases condenser capacity
143
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 that may be damaged by the test pressure.
b. Set the pressure, reducing valve for the minimum design pressure of the high side.
c. Close the liquid line shut-off valve.
d. Open the cylinder shut-off valve and disconnect the nitrogen cylinder.
e. Connect the nitrogen cylinder to the system, charging valve.
Open the cylinder shut-off valve and disconnect the nitrogen cylinder.
144
The chilling coil in an automatic purger has a primary function to:
a. Separate refrigerant vapour from the non-condensable gases to be purged.
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. Lower the operating temperature of the purger.
Separate refrigerant vapour from the non-condensable gases to be purged.
145
Before commencing to operate a new plant, or one in which piping alterations have been made, the refrigerant system must be tested for:
a. High pressure
b. Vacuum control
c. Excessive oil consumption
d. Excessive vibration
e. Leaks
e. Leaks.
146
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.
c. Overcharging the system
147
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
d. Required to be closed when charging the system
148
When charging a refrigeration system it should be done:
a. To the condenser
b. With the cooling water shut off
c. To the receiver
d. With the compressor off
e. With the liquid line shutoff valve closed
e. With the liquid line shutoff valve closed
149
Oil separators in refrigeration systems:
a. Discharge oil back into the compressor crankcase
b. Are fitted to the purge line
c. Must be water, cooled
d. Require a relief valve
e. Remove oil from the charging valve
a. Discharge oil back into the compressor crankcase
150
Charging a refrigeration system is done:
a. With the expansion valve closed
b. By adding refrigerant between the liquid shutoff valve and the expansion valve
c. With the compressor shut down
d. Between the condenser and the receiver
e. Between the suction valve and the compressor.
b. By adding refrigerant between the liquid shutoff valve and the expansion valve
151
High head pressure in a refrigeration system usually indicates:
a. Broken plates in the compressor discharge valves
b. Air or non-condensable gases in the system
c. Broken plates in the compressor suction valves
d. Lack of refrigerant in the system
e. The cooling water temperature is too low.
b. Air or non-condensable gases in the system
152
Leak testing of a refrigeration system for tightness may be done under pressure:
a. By the manufacturer
b. With oxygen
c. With ammonia
d. With an inert gas
e. With softened water
d. With an inert gas
153
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
c. Heavy white smoke
154
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 pressurised 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-pressurised after the oil has been added.
e. None of the above.
a. Oil is added by charging it into the crankcase
155
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 storage receiver
e. Between the evaporator and the compressor inlet.
c. On the liquid line after the liquid shutoff valve
156
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.
c. Residual pressure in the crankcase may blow refrigerant vapour and oil out.
157
Leak testing on a refrigeration system:
a. Is done with a sulphur stick for freon refrigerant
b. Is done with litmus paper for freon refrigerant
c. Is done with a sulphur candle for ammonia
d. Must be done with the compressor running
e. Is done with a vacuum in the system.
c. Is done with a sulphur candle for ammonia
158
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. When the unit runs continuously
e. Unit is over charged with refrigerant
e. Unit is over charged with refrigerant
159
Oil added to refrigeration compressors:
a. Is done when the compressor discharge valve is closed.
b. Is done with a vacuum in the crankcase.
c. Is done with the equalising valve closed.
d. Is done with the charging line open.
e. Must be preheated.
b. Is done with a vacuum in the crankcase
160
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. Preventative maintenance
b. Safety controls
c. Routing operation
d. Regular maintenance
e. None of the above
a. Preventative maintenance
161
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
c. The coupling is sheared or broken
162
Which of the following steps is not a step in the start-up 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. All shutoff valves in the system should be open except bypass valves used for other purposes.
c. Open shutoff valves in the cooling water supply and return lines of water-cooled condensers.
d. Valves in lines connecting suction gages should be closed.
e. Check the setting of high and low pressure cut out switches
d. Valves in lines connecting suction gages should be closed.
163
The safety control in a centrifugal compressor which ensures the compressor to only be started under a no-load condition is called what?
a. Low Oil Pressure Cut out Switch
b. Condenser High Pressure Cut out
c. Chilled Water Flow Switch
d. Motor demand limiter
e. Vane closed switch
e. Vane closed switch.
164
Checking the condition of electrical starters and contractors 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
e. Annual maintenance
165
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
b. The system’s auxiliary equipment is not electrically interlocked
166
Which of the following steps is not part of the start-up procedure of 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
c. Open the main circuit breakers
167
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. 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
a. Pump down the evaporator
168
A safety control designed to protect the chiller from freezing is the:
a. Vane closed switch.
b. Low oil pressure shut down switch.
c. Motor demand limiter.
d. Chiller water flow switch.
e. Purge unit
d. Chiller water flow switch
169
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.
b. A high discharge condition
170
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 – 15 kPa
b. 5 – 154 kPa
c. 4 – 14 kPa
d. 7 – 14 kPa
e. 10 – 20 kPa
d. 7 – 14 kPa
171
If the chilled water temperature drops approximately 2.5-3°C below the set point of the control thermostat, the chilled water low temperature cut out will:
a. Start the compressor
b. Shut down the compressor
c. Start the cooling tower fan
d. Shut down the cooling tower fan
e. Start the condenser pump.
b. Shut down the compressor
172
When the chilled water temperature rises approximately 5-6°C above the set point of the control thermostat, the:
a. Compressor will be restarted
b. Compressor will be shut down
c. Cooling tower fan will be restarted
d. Cooling tower fan will be shut down
e. Condenser pump will be restarted.
a. Compressor will be restarted
173
When some refrigeration systems are to be shut down for a prolonged period of time they should be “pumped down” and the refrigerant stored in the:
a. Evaporator
b. Condenser
c. Receiver
d. Compressor
e. Supply cylinders
c. Receiver
174
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.
c. Refrigeration compressor from starting if chilled water flow has not been established
175
Ammonia systems are seldom used for air conditioning purposes in large building mainly because ammonia:
a. Systems require a separate power supply not available in most large buildings.
b. Systems are too expensive.
c. Is too toxic.
d. Does not provide sufficient cooling power for large operations.
e. Systems require too much maintenance
c. Is too toxic.
176
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 pressurise the system
b. To evaporate the water out of the weak Lithium Bromide
c. To decrease the evaporation point of the refrigerant
d. To run the pumps which force the water through the sprayers
e. To maintain the continuous vacuum
b. To evaporate the water out of the weak Lithium Bromide
177
Which of the following is not found on the low side of an ammonia absorption refrigeration system?
a. Evaporator
b. Generator
c. Absorber
d. Cooling water
e. Low pressure ammonia vapour
b. Generator
178
In comparing absorption and compression 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
c. Cooling water requirements are larger for an absorption system than for a compression system.
179
In the Lithium Bromide system what is the function of the concentrator (regenerator)?
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
b. To increase the absorbency potential of used absorbent.
180
In order to lower the boiling point of the refrigerant in the lithium bromide system it is important that the system maintain what?
a. An extremely high vacuum
b. Very high pressure
c. Very low temperatures
d. Very fast refrigerant flow
e. High absorbent circulation
a. An extremely high vacuum
181
The absorber in the lithium bromide refrigeration system is equipped with a pump for which of the following reasons?
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
d. To speed the absorption of water vapour
182
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 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 decreases.
e. The operating cycle in the system is continuous.
d. As water vapour is absorbed by lithium bromide the vacuum decreases.
183
In a Lithium Bromide System which of the following is the refrigerant?
a. Lithium Bromide
b. Ammonia
c. Freon-22
d. Water
e. Strong aqua.
d. Water
184
In an Ammonia Absorption System what is used as the absorbent?
a. Ammonia
b. Air
c. Lithium Bromide
d. Water
e. Freon.
d. Water
185
In an absorption refrigeration system the compressor is eliminated and its functions are performed by the:
1. Condenser
2. Receiver
3. Expansion valve
4. Evaporator
5. Absorber
6. Generator
7. Pump
a. 1, 2, 3
b. 2, 3, 4
c. 3, 4, 5
d. 4, 5, 6
e. 5, 6, 7.
e. 5, 6, 7.
186
The _____ lithium bromide solution has the ability to absorb water vapor readily.
a. Hot
b. Cold
c. White
d. Weak
e. Strong
e. Strong
187
The _____ ammonia is absorbed by the _____ aqua.
a. Vaporized, weak
b. Vaporized, strong
c. Liquid, strong
d. Liquid, weak
e. Fluid, hot.
a. Vaporized, weak
188
In the ammonia absorption refrigeration system the generator is used to convert the _____ aqua to _____ aqua.
a. Strong, weak
b. Weak, strong
c. Hot, cold
d. Cold, hot
e. Black, white
a. Strong, weak
189
15. In the lithium bromide absorption refrigeration system the generator is used to convert the _____ solution to a _____ solution.
a. Strong, weak
b. Weak, strong
c. Hot, cold
d. Cold, hot
e. Black, white
b. Weak, strong
190
Which of the following is not a step in the seasonal pre-start 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
c. Turn on energy sources
191
Which of the following are elements of a mechanical purging system?
1. Purge Pickup tube
2. Purge chamber
3. Manual shutoff valve
4. Safety solenoid valve
5. Oil trap
6. Vacuum Pump
a. 1, 2
b. 1, 2, 5
c. 4, 6
d. 1, 3, 5
e. 1, 2, 3, 4, 5, 6.
e. 1, 2, 3, 4, 5, 6.
192
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. Going through the discharge valve.
d. Absorbing water vapour in the absorber
193
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. Ionisation
b. Dissociation
c. Crystallization
d. Vaporization
e. Neutralization.
c. Crystallization
194
If there is crystallization upon shutdown a possible corrective action?
a. Add octyl alcohol charge
b. Purge the system
c. Adjust cooling tower control
d. Check pump operation
e. Reduce steam pressure.
d. Check pump operation
195
When the temperature of a solution increases, which of the following statements is true?
a. The vapour pressure increases
b. Less water molecules leave the solution
c. The solubility of the salt decreases
d. The concentration decreases
e. The equilibrium constant decreases.
a. The vapour pressure increases
196
In a closed tank the salt solution is said to be in equilibrium when the:
a. Ratio of water and salt does not change.
b. Amount of water in the solution decreases.
c. Ratio of salt in the solution increases.
d. Amount of salt in the solution decreases.
e. Ratio of water in the solution increases.
a. Ratio of water and salt does not change
197
The accumulation of non-condensable gases in the absorption refrigeration system will cause:
a. An increase in capacity
b. Shorter dilution cycle
c. Longer dilution cycle
d. Lower chilled water temperatures
e. A reduction in capacity.
e. A reduction in capacity.
198
In a closed tank that is partially filled with a salt solution at a temperature well below the boiling point of the solution:
a. Some molecules of water vapor will actually escape from the solution.
b. There will be a steady stream of water vapor molecules leaving and entering the solution.
c. No molecules of water vapor will be able escape from the solution.
d. No molecules of water vapor will be absorbed back into the solution.
e. Some molecules of water vapor will actually be absorbed back into the solution.
b. There will be a steady stream of water vapor molecules leaving and entering the solution
199
10. During seasonal start-up, 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 non-condensable gases are detected in the system.
d. About one half hour after the absorption unit is started
200
When shutting down the lithium bromide 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. Turn off the air supply to the pneumatic control system
d. Open all disconnect switches
e. Service the purge pump.
b. Close the manual steam or hot water supply valve
201
The concentration of the lithium bromide solution can be most easily controlled by controlling the:
a. Volume of water sprayed into the absorber
b. Temperature in the cooling tower
c. Amount of weak Lithium Bromide pumped into the generator.
d. Pressure in the vacuum between the evaporator and the absorber.
e. Temperature in the generator.
e. Temperature in the generator
202
Which of the following is not a result of having non-condensable 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
c. Lower than normal temperatures of the chilled water leaving the evaporator
203
Octal alcohol is added to the lithium bromide solution to:
a. Act as a drying agent
b. Act as a wetting agent
c. Help the lithium bromide solution absorb ammonia
d. Help the lithium bromide solution absorb non-condensables
e. Act as a dispersing agent
b. Act as a wetting agent
204
Absorption refrigeration systems must be purged of:
a. Condensable gases
b. Air
c. Non-condensable gases
d. Nitrogen
e. Ammonia vapor.
c. Non-condensable gases
