Book 2: 5-23 - "Refrigeration Metering Devices & Capacity Controls"

Question 1

The thermal expansion valve works quite satisfactorily provided the pressure drop across the:
Select one:

A. Receiver is small

B. Condenser is small

C. Condenser is large

D. Evaporator is small

E. Evaporator is large

Answer 1

D. Evaporator is small

Question 2

One of the forces that tend to close the thermal expansion valve is the force exerted by the:
Select one:

A. Receiver inlet pressure

B. Pressure in the condenser

C. Compressor outlet pressure

D. Evaporator pressure

E. Thermal element

Answer 2

D. Evaporator pressure

Question 3

The automatic expansion valve is a liquid refrigerant control valve that maintains a constant _____ during the time the compressor is operating, regardless of load.
Select one:

A. Compressor discharge pressure

B. Evaporator pressure

C. Evaporator temperature

D. Condenser temperature

E. Condenser pressure

Answer 3

B. Evaporator pressure

Question 4

Variable inlet guide vanes are used on _____ refrigeration compressors.
Select one:

A. Centrifugal

B. Rotary lobe

C. Positive displacement

D. Sliding vane

E. Rotary screw

Answer 4

A. Centrifugal

Question 5

The high-pressure float valve is a liquid level operated control valve located on the:
Select one:

A. Low-pressure side of the system

B. High-pressure side of the system

C. Downstream side of the evaporator

D. Evaporator

E. Downstream side of the expansion valve

Answer 5

B. High-pressure side of the system

Question 6

Use of evaporator capacity control requires simultaneous control of the:
Select one:

A. Compressor capacity

B. Condenser temperature

C. Condenser capacity

D. Compressor pressure

E. Evaporator volume

Answer 6

A. Compressor capacity

Question 7

The most common application of evaporator capacity control is to use:
Select one:

A. Sectional evaporators

B. Sectional condensers

C. Adjustable evaporators

D. Sectional receivers

E. Variable evaporators

Answer 7

A. Sectional evaporators

Question 8

With the intermittent operation system of refrigeration compressor control the compressor is started and stopped based on the:
Select one:

A. Size of the substance to be cooled

B. Temperature of the refrigerant

C. Temperature of the condenser

D. Pressure of the condenser

E. Temperature of the substance to be cooled

Answer 8

E. Temperature of the substance to be cooled

Question 9

A refrigeration system using a high-pressure float provides for storage of the refrigerant in the:
Select one:

A. Compressor

B. Condenser

C. Receiver

D. Expansion valve

E. Evaporator

Answer 9

E. Evaporator

Question 10

All of the following methods are used to control the refrigeration compressor output except:
Select one:

A. Variable inlet guide vanes

B. Speed control

C. Cylinder Unloaders

D. Intermittent operation

E. Thermodynamic expansion valve

Answer 10

E. Thermodynamic expansion valve

Question 11

The thermostatic expansion valve must admit enough liquid to maintain the superheat at the evaporator outlet at _____ to provide for maximum evaporator efficiency.
Select one:

A. 10°C to 11°C (50°F to 52°F)

B. 8°C to 9°C (46°F to 48°F)

C. 2°C to 3°C (36°F to 38°F)

D. 5°C to 6°C (41°F to 43°F)

E. 0°C to 1°C (32°F to 34°F)

Answer 11

D. 5°C to 6°C (41°F to 43°F)

Question 12

The bulb of a thermostatic expansion valve is sensitive to the:
Select one:

A. Pressure changes in the condenser

B. Temperature changes in the receiver

C. Pressure changes in the evaporator

D. Temperature changes in the condenser

E. Temperature changes in the evaporator

Answer 12

E. Temperature changes in the evaporator

Question 13

An automatic expansion or constant pressure valve is suitable when compressors are controlled by a:
Select one:

A. Humidistat

B. Rheostat

C. Thermostat

D. Aquastat

E. Pressurestat

Answer 13

C. Thermostat

Question 14

The cylinder bypass method of refrigeration compressor capacity control requires returning high-temperature vapour back to the compressor inlet this hot vapor must be tempered by using the _____ expansion valve to mix a low-temperature saturated mixture of refrigerant with the compressor discharge vapor.
Select one:

A. Hand

B. Capillary

C. Thermodynamic

D. De-superheating

E. Automatic

Answer 14

D. De-superheating

Question 15

The charge of refrigerant in a system with a high-pressure float valve is critical. Insufficient liquid refrigerant in the evaporator may starve the:
Select one:

A. Evaporator and increase the capacity of the system

B. Receiver and increase the capacity of the system

C. Condenser and increase the capacity of the system

D. Evaporator and reduce the capacity of the system

E. Condenser and reduce the capacity of the system

Answer 15

D. Evaporator and reduce the capacity of the system

Question 16

The bulb of a thermostatic expansion valve is usually charged with:
Select one:

A. Instrument oil

B. Alcohol

C. The same refrigerant that is used in the system

D. Water

E. Nitrogen

Answer 16

C. The same refrigerant that is used in the system

Question 17

To compensate for a large pressure drop in an evaporator, the thermal expansion valve is equipped with an equalizing line which connects the underside of the diaphragm or bellows with the:
Select one:

A. Inlet of the evaporator instead of the outlet

B. Inlet of the condenser instead of the outlet

C. Outlet of the receiver instead of the inlet

D. Outlet of the condenser instead of the inlet

E. Outlet of the evaporator instead of the inlet

Answer 17

E. Outlet of the evaporator instead of the inlet

Question 18

The low-pressure float valve is a liquid level operated control valve used to maintain a constant level of liquid refrigerant in the:
Select one:

A. Expansion valve

B. Receiver

C. Compressor

D. Evaporator

E. Condenser

Answer 18

D. Evaporator

Question 19

The force that tends to open the thermal expansion valve is the force exerted by the:
Select one:

A. Pressure in the condenser

B. Thermal element

C. Spring

D. Compressor outlet pressure

E. Pressure in the evaporator

Answer 19

B. Thermal element

Question 20

One of the disadvantages of evaporator capacity control by face damper is that the:
Select one:

A. Refrigerant volume to the space is reduced

B. Temperature of the space is reduced

C. Refrigerant pressure to the space is reduced

D. Temperature of the space is increased

E. Air volume to the space is reduced

Answer 20

E. Air volume to the space is reduced