Unit 9 Refrigeration

Question 1

Which of the following is NOT a form of refrigeration evaporator construction? 
Select one:
a. Bare tube 
b. Plate surface 
c. Shell and tube 
d. Finned tube 
e. Double-tube

Answer 1

e. Double-tube

Question 2

Ammonia piping (according to IIAR), should be labelled in:

Select one:

a. Red background with white letters
b. Orange background with white letters
c. Orange background with black letters
d. Yellow background with black letters

Answer 2

c. Orange background with black letters

Question 3

What is the Permissible Exposure Limit for R-717?

Select one:

a. 300 ppm
b. 50 ppm
c. 70 ppm
d. 2 ppm

Answer 3

b. 50 ppm

Question 4

Which of the following characteristics is common to all of the group B refrigerants?
Select one:
a. High toxicity 
b. High flammability
c. Low Ozone Depleting Potential
d. High Global Warming Potential

Answer 4

a. High toxicity

Question 5

When a liquid evaporates, it 
Select one:
a. Gains sensible heat 
b. Gains latent heat  
c. Loses sensible heat 
d. Loses latent heat

Answer 5

b. Gains latent heat

Question 6

Which of the following is NOT a common type of refrigeration condenser? 
Select one:
a. Flooded  
b. Air-cooled 
c. Shell and tube 
d. Shell and coil

Answer 6

a. Flooded

Question 7

Heat that causes an increase in temperature, is called \_\_\_\_\_ heat: 
Select one:
a. Radiant 
b. Sensible  
c. Latent 
d. Convective

Answer 7

b. Sensible

Question 8

Of the following refrigeration system evaporators, the \_\_\_\_\_\_\_\_\_\_\_ evaporators require the largest refrigerant charge. 
Select one:
a. Direct expansion 
b. Bare tube 
c. Plate surface 
d. Flooded  
e. Finned tube

Answer 8

d. Flooded

Question 9

A liquid trap located in the suction line before a refrigeration compressor, which evaporates liquid refrigerant and returns it to the compressor as a gas, is called: 
Select one:
a. An oil separator 
b. A strainer-drier 
c. A distributor 
d. An accumulator

Answer 9

d. An accumulator

Question 10

Which of the following is NOT a function of the refrigeration compressor?
Select one:
a. Raises the pressure of the refrigerant
b. Raises the temperature of the refrigerant
c. Maintains a low pressure in the evaporator
d. Removes energy from the vapour

Answer 10

d. Removes energy from the vapour

Question 11

In order to lower the boiling point of the refrigerant in the lithium bromide refrigeration system, it is important that the system maintain 
Select one:
a. An extremely high vacuum 
b. Very high pressure 
c. Very low temperatures 
d. High absorbent circulation rates

Answer 11

a. An extremely high vacuum

Question 12

The accessory that maintains efficient heat transfer by collecting oil before it coats the tubes of the condenser is called: 
Select one:
a. A filter-drier 
b. An oil scrubber 
c. An adsorber
d. An oil separator

Answer 12

d. An oil separator

Question 13

The CSA B52 code requires that \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ shall be provided on all systems operating above atmospheric pressure. 
Select one:
a. pressure limiting devices  
b. temperature cutout devices 
c. flow switches
d. purgers

Answer 13

a. pressure limiting devices

Question 14

The net refrigerating effect of a refrigerant is the amount of heat:
Select one:
a. Discharged by the condenser
b. Absorbed by the refrigerant in the evaporator
c. Added to the refrigerant by the compressor
d. Discharged by the refrigerant in the evaporator

Answer 14

b. Absorbed by the refrigerant in the evaporator

Question 15

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. 
Select one:
a. 10% 
b. 150%
c. 103 kPa
d. 25%

Answer 15

a. 10%

Question 16

The function of the condenser in a refrigeration system is to:
Select one:
a. Lower the temperature of the liquid refrigerant
b. Change high pressure refrigerant vapour to liquid
c. Lower the temperature of the refrigerant vapour
d. Lower the liquid refrigerant pressure

Answer 16

b. Change high pressure refrigerant vapour to liquid

Question 17

Which of the following statements about double tube refrigeration condensers is true?
Select one:
a. They consist of two separate tubes side by side.
b. They are easy to clean.
c. Water flows in the inner tube in the opposite direction of the flow of refrigerant.
d. They are the most efficient of all condensers.

Answer 17

c. Water flows in the inner tube in the opposite direction of the flow of refrigerant.

Question 18

Absorption refrigeration systems may use waste in order to
Select one:
a. pressurize the system
b. evaporate water from the weak lithium bromide
c. decrease the evaporation point of the refrigerant
d. maintain a minimum load on the system, during periods of low cooling demand
e. To increase the lithium boiling point.

Answer 18

b. evaporate water from the weak lithium bromide

Question 19

Which of the following statements about refrigeration pressure gauges is TRUE?
Select one:
a. Refrigeration pressure gauges can indicate saturation temperatures in a system.
b. The CSA B52 Code requires permanently installed pressure gauges on all refrigeration systems.
c. Only one pressure gauge is normally installed on a system.
d. Permanently installed pressure gauges shall be constructed for at least 1.5 times the high side design pressure.

Answer 19

a. Refrigeration pressure gauges can indicate saturation temperatures in a system.

Question 20

The refrigeration condenser design that requires chemical cleaning, because it cannot be mechanically cleaned, is the: 
Select one:
a. Shell and tube condenser 
b. Shell and coil condenser
c. Air-cooled condenser
d. Evaporative condenser

Answer 20

b. Shell and coil condenser

Question 21

The rate at which a refrigeration system removes heat from the refrigerated medium is defined as: 
Select one:
a. the Coefficient of Performance
b. the Net Cooling Effect
c. the refrigeration capacity. 
d. the Compression Ratio

Answer 21

c. the refrigeration capacity.

Question 22

A chemical dot placed under the lens of a sight glass that is exposed to liquid refrigerant monitors
Select one:
a. Liquid flow
b. Refrigerant levels
c. The presence of moisture in the refrigerant
d. Vapour flow

Answer 22

c. The presence of moisture in the refrigerant

Question 23

Which of the following is NOT considered a rotary refrigeration compressor design? 
Select one:
a. Screw  
b. Sliding vane  
c. Scroll 
d. Centrifugal

Answer 23

d. Centrifugal

Question 24

Refrigeration valves should be identified with a tag that has:

Select one:

a. the fluid temperature, pressure, and state
b. the temperature, pressure, and type of fluid
c. the valve number in the system, the fluid, and its state
d. the valve number in the system, the fluid temperature, and its state

Answer 24

c. the valve number in the system, the fluid, and its state

Question 25

``` A sulfur candle is used to test for Select one: a. R-744 leaks b. R-717 leaks c. R-290 leaks d. CFC leaks ```

Answer 25

b. R-717 leaks

Question 26

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

Answer 26

e. boil liquid refrigerant at low pressure and low temperature

Question 27

The low oil pressure cut-off switches of a mechanical refrigeration system Select one: a. keep the compressor oil pressure at a level where the oil will not freeze b. prevent compressor start-up if the oil heater fails c. shut down the compressor when the oil pressure drops below the minimum required value d. keep the oil from gelling at low pressure

Answer 27

c. shut down the compressor when the oil pressure drops below the minimum required value

Question 28

``` An evaporator that can easily be cleaned and defrosted manually without interrupting the cooling process is which type of evaporator? Select one: a. Liquid recirculating evaporator b. Finned evaporator c. Plate surface evaporator d. Shell and tube evaporator ```

Answer 28

c. Plate surface evaporator

Question 29

``` R-744 is non-toxic and non-flammable. Which safety group does it belong to? Select one: a. Group A2 b. Group B4 c. Group A1 d. Group A3 ```

Answer 29

c. Group A1

Question 30

``` The most widely used refrigerant metering device, which consists of a pressure-sensitive bellows or diaphragm connected to a temperature sensing bulb, is the Select one: a. thermostatic expansion valve b. automatic expansion valve c. capillary tube d. manual expansion valve ```

Answer 30

a. thermostatic expansion valve

Question 31

``` One tonne of refrigeration is: Select one: a. 13958 kJ per day b. 1000 kg of mass c. 233 kJ per minute d. 13958 J per hour ```

Answer 31

c. 233 kJ per minute

Question 32

The expansion valve in a refrigeration system Select one: a. Expands the liquid to the receiver b. Regulates the liquid refrigerant flow to the evaporator c. Is used to charge the refrigeration system d. Isolates the compressor from the condenser

Answer 32

b. Regulates the liquid refrigerant flow to the evaporator

Question 33

Which of the following is not a component of the low pressure side of a compression refrigeration system? Select one: a. Compressor discharge piping b. The evaporator c. The downstream side of the expansion valve d. The suction line

Answer 33

a. Compressor discharge piping

Question 34

Which of the following steps is NOT part of a start-up of a reciprocating or rotary compressor refrigerating system? Select one: a. Check for proper oil level in the compressor b. Open shutoff valves in the cooling water supply and return lines of water-cooled condensers c. Valves in pressure piping should be closed d. Check the setting of high and low pressure cut-off switches

Answer 34

c. Valves in pressure piping should be closed

Question 35

Which is NOT a factor in determining the degree of hazard of a refrigerant? Select one: a. Leakage probability of the system b. Amount of refrigerant in the system c. Type of compressor used d. Toxicity or flammability

Answer 35

c. Type of compressor used

Question 36

``` The refrigeration evaporator that increases heat exchange by crimping several thin metal plates to single-wall tubes is a Select one: a. Plate surface evaporator b. Bare tube evaporator c. Shell and tube evaporator d. Finned tube evaporator ```

Answer 36

d. Finned tube evaporator

Question 37

Moisture in a refrigeration system will NOT cause Select one: a. The formation of ice inside the refrigeration system. b. Acid formation inside the refrigeration system. c. The deterioration of the motor insulation of a hermetic compressor. d. Excessive high-side pressures.

Answer 37

d. Excessive high-side pressures.

Question 38

``` What type of evaporator contains only a small amount of liquid refrigerant at any time? Select one: a. Dry evaporator b. Flooded evaporator c. A liquid overfeed evaporator d. A bare-tube evaporator ```

Answer 38

a. Dry evaporator

Question 39

``` A direct expansion type evaporator that has more than one refrigerant circuit requires __________ to provide even refrigerant flow in each circuit. Select one: a. An expansion valve b. A distributor c. A purge valve d. A backpressure regulator ```

Answer 39

b. A distributor

Question 40

``` The saturation temperature of a refrigerant is the same as its: Select one: a. Boiling point b. Freezing point c. Saturation pressure d. Fire point ```

Answer 40

a. Boiling point