Book 2 Chapter 16: Refrigerants

Question 1

What is the classification of a refrigerant that is highly flammable but exhibits low toxicity?
A) A1
B) A3
C) B2
D) B3

Answer 1

B) A3

Question 2

What is the building temperature of R-717 (ammonia) at atmospheric conditions?
A) 47.6ºC (117.68ºF)
B) -33.3ºC (-27.94ºF)
C) -26.1ºC (-14.98ºF)
D) -40.8ºC (-41.44ºF)

Answer 2

B) -33.3ºC (-27.94ºF)

Question 3

What are the factors that affect the leakage tendency of a refrigerant?
A) Operating pressure
B) Density
C) Molecular mass
D) All of the above

Answer 3

D) All of the above

Question 4

The use of oil-miscible refrigerants:
A) Dissolves most of the oil in the system components
B) Returns the oil to the compressor
C) Avoids problems due to oil blockage
D) All of the above

Answer 4

D) All of the above

Question 5

The refrigerating effect of a refrigerant is:
A) Greater than its latent heat of vaporization
B) Less than its latent heat of vaporization
C) Equal to its specific heat capacity
D) Equal to its latent heat of vaporization
E) Equal to its specific volume

Answer 5

D) Equal to its latent heat of vaporization

Question 6

Which of the following characteristics is common in all of the group B refrigerants?
A) Low toxicity
B) Average flammability
C) Low flammability
D) High toxicity
E) High flammability

Answer 6

D) High toxicity

Question 7

The ability of a refrigerant to be dissolved into oil and vice versa is called:
A) Miscibility
B) Density
C) Enthalpy
D) Leakage tendency
E) Moisture reaction

Answer 7

A) Miscibility

Question 8

Which of the following is not a physical property of refrigerants?
A) Toxicity
B) Leakage tendency
C) Explosiveness
D) Oxidization
E) Odour

Answer 8

D) Oxidization

Question 9

Molecular mass is a dependent factor in which of the following physical properties of a refrigerant?
A) Flammability
B) Explosiveness
C) Toxicity
D) Leakage tendancy
E) Miscibility

Answer 9

D) Leakage tendancy

Question 10

Group “A1” refrigerants as found in the current code are:
A) Non-flammable and non-toxic
B) Toxic and non-flammable
C) Low-toxic and flammable
D) Low-flammable and toxic
E) High-toxic and flammable

Answer 10

A) Non-flammable and non-toxic

Question 11

The standard refrigeration cycle is used to compare refrigerants and machines operating under comparable conditions. These standard conditions are:
A) 103ºC and atmospheric pressure
B) -30ºC for the condenser and 15ºC for the evaporator
C) 103 kPa and ambient temperature
D) 30ºC for the condenser and -15ºC for the evaporator
E) 30ºC and atmospheric pressure

Answer 11

D) 30ºC for condenser and -15ºC for the evaporator

Question 12

The property which must be known to calculate the size of control valves pipings, etc is:
A) Refrigerating effect
B) Boiling point
C) Specific volume
D) Enthalpy
E) Density

Answer 12

E) Density

Question 13

R-134a (1,1,1,2-tetrafluoroethane) is non-toxic and non-flammable. Which of the following group does it belong to?
A) Group A1
B) Group A2
C) Group A3
D) Group B2
E) Group B4

Answer 13

A) Group A1

Question 14

The practical refrigerating effect of a refrigerant is:
A) Equal to its latent heat of vaporization
B) Equal to its specific heat capacity
C) Less than its latent heat of vaporization
D) Greater than its latent heat of vaporization
E) Equal to its specific volume

Answer 14

C) Less than its latent heat of vaporization

Question 15

According to the refrigeration tables which of the following is the corresponding temperature at an absolute pressure of 103.05 kPa for R-717?
A) -33ºC
B) 10ºC
C) -75ºC
D) -101ºC
E) 115ºC

Answer 15

A) -33ºC

Question 16

Which refrigerant is corrosive to copper, flammable, readily absorbs in water, is toxic, has the highest refrigerating effect?
A) Dichlorotetrafluoroethane R-114
B) Freon R-22
C) Freon R-134
D) Freon R-12
E) Ammonia R-717

Answer 16

E) Ammonia R-717

Question 17

Refrigerants that are flammable and have low toxicity belong to Group:
A) A3
B) A2
C) B1
D) A1
E) B2

Answer 17

B) A2

Question 18

The condition known as “standard condition” indicates a standard evaporator temperature of:
A) 30ºC (86ºF)
B) -30ºC (-22ºF)
C) -15ºC (5ºF)
D) -10ºC (14ºF)
E) 15ºC (59ºF)

Answer 18

C) -15ºC (5ºF)

Question 19

In an ideal situation the refrigerating effect of a refrigerant is equal to the _______ of the refrigerant.
A) Temperature of fusion
B) Temperature of evaporation
C) Sensible heat of fusion
D) Latent heat of fusion
E) Latent heat of evaporation

Answer 19

D) Latent heat of fusion

Question 20

Which one of the following factors affect the leakage tendency of a refrigerant?
A) Temperature
B) Specific volume
C) Molecular mass
D) Miscibility
E) Enthalpy

Answer 20

C) Molecular mass

Question 21

Moisture in the refrigerant may lead to:
A) Over cooling of the refrigerant
B) High pressure in the evaporator
C) Acid formation resulting in corrosion, sludge formation in the compressor crank case
D) Ice formation in the condenser
E) Low temperature in the condenser

Answer 21

C) Acid formation resulting in corrosion, sludge formation in the compressor crank case

Question 22

What is the boiling temperature of R-22 (Freon 22) at atmospheric conditions?
A) -26.1ºC (-14.98ºF)
B) 47.6ºC (117.68ºF)
C) -40.8ºC (-41.44ºF)
D) 3.6ºC (38.5ºF)
E) -33.3ºC (-27.94ºF)

Answer 22

C) -40.8ºC (-41.44ºF)

Question 23

Refrigerants that are non-flammable and highly toxic belong to Group:
A) B2
B) A3
C) B3
D) B1
E) A2

Answer 23

D) B1

Question 24

The ability of a refrigerant to be dissolved into oil and vice versa is called:
A) Enthalpy
B) Leakage tendency
C) Density
D) Moisture reaction
E) Miscibility

Answer 24

E) Miscibility

Question 25

Which of the following refrigerants has a strong, pungent smell?
A) Freon 22 (R-22)
B) Freon 134a (R-134a)
C) Ammonia (R-717)
D) Freon 11 (R-11)
E) Freon 12 (R-12)

Answer 25

C) Ammonia (R-717)