Chapter 24 Refrigeration Cycle Controls

Question 1

1. One of the most important secondary controls in a refrigerating system is the
refrigerant flow control used to regulate the amount of liquid refrigerant flowing into
the:
A. Refrigerator
B. Condenser
C. Evaporator
D. Receiver
E. Refrigerated space

Answer 1

C. Evaporator

Question 2

2. The thermostatic refrigeration controller has a range adjustment that sets the
   temperature level at which the:
   A. Expansion valve opens and closes
   B. Level in the evaporator control activates
   C. Cut-in and cut-out occurs
   D. Condenser cooling water control activates
   E. Fan starts and stops

Answer 2

C. Cut-in and cut-out occurs

Question 3

3. The thermostatic refrigeration controller has a differential adjustment that sets the
   temperature at which the:
   A. Expansion valve opens and closes
   B. Level in the evaporator control activates
   C. Condenser cooling water control activates
   D. Cut-in and cut-out occurs
   E. Fan starts and stops

Answer 3

D. Cut-in and cut-out occurs

Question 4

4. With the direct type of temperature-actuated refrigeration control the thermostat is
located directly in the:
A. Evaporator
B. Condenser
C. Refrigerator
D. Space to be cooled
E. Receive

Answer 4

D. Space to be cooled

Question 5

5. With the indirect type of temperature-actuated refrigeration control the bulb is
installed in the \_\_\_\_\_ while the remainder of the control is located outside in a
convenient location.
A. Evaporator
B. Condenser
C. Refrigerator
D. Receiver
E. Refrigerated space

Answer 5

E. Refrigerated space

Question 6

6. An evaporator pressure regulator prevents _____ conditions from occurring in the
   evaporator while the compressor is running.
   A. Low pressure and temperature
   B. High pressure and temperature
   C. Low pressure and high temperature
   D. High pressure and low temperature
   E. Low pressure and humidity

Answer 6

A. Low pressure and temperature

Question 7

7. The \_\_\_\_\_ is used in those systems where a drop in temperature below the
minimum setting of the operating thermostat could result in damage to the
equipment.
A. Pressure limiting device
B. Low limit thermostat
C. Pressure-operated safety switch
D. Evaporator pressure regulator
E. Solenoid valve

Answer 7

B. Low limit thermostat

Question 8

8. The CSA B52 Mechanical Refrigeration Code requires the pressure limiting device
   to be connected between the: CSA B52
   A. Compressor and the first stop valve in the suction line
   B. Condenser and the first stop valve in the discharge line
   C. Evaporator and the first stop valve in the discharge line
   D. Condenser and the first stop valve in the suction line
   E. Compressor and the first stop valve in the discharge line

Answer 8

E. Compressor and the first stop valve in the discharge line

Question 9

9. The CSA B52 Mechanical Refrigeration Code requires that the pressure limiting
   device be designed to stop the action of the compressor or generator at a pressure
   not more than _____ of the system high side design pressure.
   A. 80%
   B. 100%
   C. 70%
   D. 90%
   E. 60%

Answer 9

D. 90%

Question 10

10.The CSA B52 Mechanical Refrigeration Code requires that all refrigeration
systems containing more than _____ kg of refrigerant and operating above
atmospheric pressure shall be equipped with a pressure limiting device.
A. 5 kg (11 lb)
B. 15 kg (33.1 lb)
C. 9 kg (19.8 lb)
D. 20 kg (44.1 lb)
E. 12 kg (26.4 lb)

Answer 10

C. 9 kg (19.8 lb)

Question 11

11.The pressure-actuated refrigeration control is actuated by the:

A. Discharge pressure of the compressor
B. Suction pressure of the condenser
C. Discharge pressure of the receiver
D. Suction temperature of the compressor
E. Suction pressure of the compressor

Answer 11

E. Suction pressure of the compressor

Question 12

12. The high-pressure safety cutout protects the refrigerating system from higher than normal pressures due to the:
    A. Presence of non-condensables in evaporator
    B. Presence of non-condensables in the system
    C. Loss of refrigerant
    D. High compressor oil pressure
    E. Presence of refrigerants in the system

Answer 12

B. Presence of non-condensables in the system

Question 13

13.	The high oil temperature cutout is a safety control that shuts down the compressor when the lubricating oil temperature becomes too high due to:
A.	Loss of refrigerant
B.	Evaporator high temperature
C.	Condenser high pressure
D.	Condenser high temperature
E.	Loss of oil cooling

Answer 13

E. Loss of oil cooling

Question 14

14. The low oil sump temperature protection device prevents the compressor from starting if the oil temperature falls below a preset value so that:
    A. The oil will flow freely
    B. The oil viscosity will be low enough
    C. Any refrigerant dissolved in the oil is separated from the lubricant.
    D. The oil will drain from the condenser
    E. The oil will drain from the evaporator

Answer 14

C. Any refrigerant dissolved in the oil is separated from the lubricant.

Question 15

15. The condenser automatic cooling water regulating valve is operated by the:
    A. Liquid pressure on the compressor discharge
    B. Vapour pressure on the compressor suction
    C. Liquid pressure on the compressor suction
    D. Vapour pressure on the evaporator discharge
    E. Vapour pressure on the compressor discharge

Answer 15

E. Vapour pressure on the compressor discharge

Question 16

16. The high motor temperature cutout stops the compressor if there is a loss of motor cooling or a motor overload due to malfunction of the:
    A. Operating controls
    B. High-pressure safety cutout
    C. Low limit thermostat
    D. High oil temperature cutout
    E. Condenser cooling water regulating valve

Answer 16

A. Operating controls

Question 17

17.	The operation of the compressor (starting, stopping, and unloading) may be accomplished by a \_\_\_\_\_ type of actuated control.
A.	Volume Humidity
B.	Pressure
C.	Mass
D.	Density
E.	Level

Answer 17

B. Pressure

Question 18

18.	The operation of the compressor (starting, stopping, and unloading) may be accomplished by a \_\_\_\_\_ type of actuated control. 
A.	Humidity
B.	Volume
C.	Mass
D.	Density
E.	Level

Answer 18

A. Humidity

Question 19

19.	The operation of the compressor (starting, stopping, and unloading) may be accomplished by a \_\_\_\_\_ type of actuated control.
A.	Volume Humidity
B.	Mass
C.	Temperature
D.	Density
E.	Level

Answer 19

C. Temperature

Question 20

20.	Flow switches are used on chilled water and cooling water lines and air ducts are used as \_\_\_\_\_ switches. 
A.	Evaporator level control
B.	Condenser pressure control
C.	Over pressure lockout
D.	Safety lockout
E.	Low temperature lockout

Answer 20

D. Safety lockout

Question 21

21.	The thermostatic refrigeration controller produces mechanical when subjected to \_\_\_\_\_ fluctuations in the cooled medium. 
A.	Pressure
B.	Temperature
C.	Electrical
D.	Electronic
E.	Humidity

Answer 21

B. Temperature

Question 22

22. Motor overload protection is a manual reset device that will take the motor itself offline when the current drawn by the motor exceeds:
    A. Its minimum allowable value
    B. Its maximum allowable value
    C. The condenser maximum allowable pressure
    D. The evaporator maximum allowable temperature
    E. Its maximum allowable oil temperature

Answer 22

B. Its maximum allowable value

Question 23

23.	The sensing device of a humidistat may consist of a/an \_\_\_\_\_ element.
A.	Hydroscopic
B.	Hygroscopic
C.	Hydroponic
D.	Pneumatic
E.	Hydrophobic

Answer 23

B. Hygroscopic

Question 24

24.	The pressure-operated safety switch is used to protect the refrigeration system against a lower than normal \_\_\_\_\_ pressure.
A.	Compressor suction
B.	Condenser suction
C.	Condenser discharge
D.	Evaporator suction
E.	Condenser cooling water

Answer 24

A. Compressor suction

Question 25

25. In the event of a low oil pressure condition, the oil pressure failure switch will:
    A. Open the recycle valve to take the load off the compressor
    B. Stop the flow of refrigerant to the system
    C. Shutdown the compressor
    D. Sound an audible alarm
    E. Stop the air circulation fan

Answer 25

C. Shutdown the compressor