Chapter 25 Compression Refrigeration System Pre-Startup Procedures

Question 1

1. Just before charging an empty refrigerating system, the entire system should be:
   A. Pressure tested
   B. Boiled out
   C. Pressures to the maximum allowable working pressure
   D. Put under a very high vacuum
   E. Hydro tested

Answer 1

D. Put under a very high vacuum

Question 2

2. Higher than normal head pressure is undesirable because of all of the following except it:
   A. Creates lower evaporator pressure
   B. Increases power consumption
   C. Reduces compressor capacity
   D. Over stresses the compressor parts
   E. Is detrimental to compressor valves and lubrication

Answer 2

A. Creates lower evaporator pressure

Question 3

3.	If the pressure does not drop noticeably on both sides of the refrigeration system all pipe joints in the system should be tested for leaks using: 
A.	Litmus paper
B.	An electronic tester
C.	A soap solution
D.	A halide torch
E.	Water

Answer 3

B. An electronic tester

Question 4

4.	Positive pressure testing of a refrigeration system is done using dry \_\_\_\_\_ gas as the pressure agent. 
A.	Nitrogen
B.	Carbon monoxide
C.	Oxygen
D.	Hydrogen sulphide
E.	Helium

Answer 4

A. Nitrogen

Question 5

5. Once any leaks found in the system are repaired:
   A. Refrigerant can be added to the system
   B. The system should be evacuated
   C. The system is ready for operation
   D. A second pressure test should be conducted
   E. The pressure can be released

Answer 5

D. A second pressure test should be conducted

Question 6

6. Oil is added to the refrigeration system by _____ while the compressor is in operation.
   A. Pouring it into the crankcase
   B. Charging it into the condenser with a suitable pump
   C. Charging it into the evaporator with a suitable pump
   D. Charging it into the crankcase with a suitable pump
   E. Pouring it into the condenser

Answer 6

D. Charging it into the crankcase with a suitable pump

Question 7

7.	What personal protective equipment (PPE) is required when charging a system with refrigerant?
A.	Rubber gloves
B.	Face shield
C.	Goggles
D.	Encapsulated suit
E.	Self contained breathing apparatus

Answer 7

C. Goggles

Question 8

8.	Regulations of the authority having jurisdiction may require that a \_\_\_\_\_ be reported. 
A.	Flush of the condenser
B.	Evacuation of the evaporator
C.	Change of the compressor
D.	Loss of refrigerant
E.	Loss of cooling water

Answer 8

D. Loss of refrigerant

Question 9

9.	Non-condensable gases in a refrigeration system consist mainly of \_\_\_\_\_ that may have leaked into the system by improper operating or maintenance procedures. 
A.	Impurities in the refrigerant
B.	Air
C.	Gases caused by lubrication breakdown
D.	Sulphur dioxide
E.	Nitrogen oxide

Answer 9

B. Air

Question 10

10.	The initial refrigerant charge is given on the \_\_\_\_\_ side of the system. 
A.	Low-pressure
B.	High-pressure
C.	Evaporator
D.	Compressor inlet
E.	Expansion valve outlet

Answer 10

B. High-pressure

Question 11

11. Overcharging a system causes _____ creating high compressor power consumption.
    A. High compressor suction and discharge pressures
    B. Low suction evaporator pressure
    C. High condenser pressure
    D. High receiver temperature
    E. Low evaporator temperature

Answer 11

A. High compressor suction and discharge pressures

Question 12

12.	Evacuation of the refrigeration system should not be attempted unless the temperature of the surrounding air is \_\_\_\_\_ or higher. 
A.	0°C (32°F)
B.	5°C (41°F)
C.	10°C (50°F)
D.	15°C (59°F)
E.	20°C (68°F)

Answer 12

E. 20°C (68°F)

Question 13

13. The low-pressure side is isolated when its minimum design pressure is reached and then the pressurizing gas is admitted to the refrigeration system high-pressure side and increased to the required:
    A. High-pressure side minimum design pressure
    B. Low-pressure side operating pressure
    C. High-pressure side operating pressure
    D. Low-pressure side minimum design pressure
    E. High-pressure side maximum design pressure

Answer 13

A. High-pressure side minimum design pressure

Question 14

14.	Regulations of the authority having jurisdiction may require that a \_\_\_\_\_ be reported.
A.	Flush of the condenser
B.	Evacuation of the evaporator
C.	Change of the compressor
D.	Loss of refrigerant
E.	Loss of cooling water

Answer 14

D. Loss of refrigerant

Question 15

15. Purge systems are required on refrigeration systems that operate:
    A. Below atmospheric temperature
    B. Below atmospheric pressure
    C. Above atmospheric temperature
    D. Only with ammonia as the refrigerant
    E. Without a qualified operator in attendance

Answer 15

B. Below atmospheric pressure

Question 16

16.	Frost formation on the suction line in a \_\_\_\_\_ system may indicate overcharging. 
A.	Automatic expansion
B.	Capillary tube
C.	Thermostatic expansion
D.	Low-pressure float
E.	High-pressure float

Answer 16

B. Capillary tube

Question 17

17.	Escaping refrigerant will be drawn into the halide torch detectors tube and travel to the burner causing the flame to turn a brilliant: 
A.	Red
B.	Green
C.	Orange
D.	Yellow
E.	Purple

Answer 17

B. Green

Question 18

18.	During charging of the refrigeration system short cycling of the compressor should be avoided due to the starting stress which is placed on the: 
A.	Expansion valve
B.	Condenser cooling water valve
C.	Evaporator level control
D.	Compressor valves
E.	Compressor motor

Answer 18

E. Compressor motor

Question 19

19.	Wetted litmus paper detects leaks in ammonia refrigeration systems by changing the colour of the litmus paper to a: 
A.	White
B.	Bright green
C.	Light blue
D.	Orange
E.	Reddish hue

Answer 19

E. Reddish hue

Question 20

20.	Caution when burned the halocarbon refrigerants containing fluorine produce a very toxic \_\_\_\_\_ gas. 
A.	Hydrogen sulphide
B.	Sulphur dioxide
C.	Carbon monoxide
D.	Phosgene
E.	Mustard

Answer 20

D. Phosgene

Question 21

21.	During the charging process the refrigerant that passes through the system is stored in liquid form in the:
A.	Evaporator
B.	Chiller
C.	Compressor
D.	Receiver
E.	Expansion valve

Answer 21

D. Receiver

Question 22

22. As the pressurizing gas is admitted to the refrigeration system the pressure is first increased to the required:
    A. High-pressure side minimum design pressure
    B. Low-pressure side operating pressure
    C. High-pressure side operating pressure
    D. Low-pressure side minimum design pressure
    E. High-pressure side maximum design pressure

Answer 22

D. Low-pressure side minimum design pressure

Question 23

23. Just before charging an empty refrigerating system, the entire system should be:
    A. Pressure tested
    B. Boiled out
    C. Pressures to the maximum allowable working pressure
    D. Put under a very high vacuum
    E. Hydro tested

Answer 23

D. Put under a very high vacuum

Question 24

24. The refrigeration system condenser pressure should be slightly higher than the saturation pressure corresponding to the temperature of the refrigerant in the:
    A. Evaporator
    B. Downstream side of the expansion valve
    C. Upstream side of the compressor
    D. Accumulator
    E. Condenser

Answer 24

E. Condenser