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Second Half Book 2 > chapter 25 > Flashcards

chapter 25 Flashcards

1
Q

It is the _____ part of the refrigerant molecular composition that during combustion causes the green flame of the halide detector.
Select one:

A.
Chlorine

B.
Carbon

C.
Iodine

D.
Fluorine

E.
Hydrogen

A

A.
Chlorine

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2
Q

Oil is added to the refrigeration system by _____ while the compressor is in operation.
Select one:

A.
Charging it into the crankcase with a suitable pump

B.
Charging it into the evaporator with a suitable pump

C.
Pouring it into the condenser

D.
Charging it into the condenser with a suitable pump

E.
Pouring it into the crankcase

A

A.
Charging it into the crankcase with a suitable pump

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3
Q

What personal protective equipment (PPE) is required when charging a system with refrigerant?
Select one:

A.
Face shield

B.
Self contained breathing apparatus

C.
Encapsulated suit

D.
Goggles

E.
Rubber gloves

A

D.
Goggles

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4
Q

Non-condensable gases in a refrigeration system consist mainly of _____ that may have leaked into the system by improper operating or maintenance procedures.
Select one:

A.
Sulphur dioxide

B.
Gases caused by lubrication breakdown

C.
Impurities in the refrigerant

D.
Air

E.
Nitrogen oxide

A

D.
Air

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5
Q

If any moisture or water vapour is present in a refrigerating system that contains chlorine or fluorine an acid is formed that reacts with the compressor oil to produce sludge that will:
Select one:

A.
Clog the condenser

B.
Plug the expansion valve

C.
Coat the evaporator

D.
Restrict cooling water flow

E.
Corrode metal parts

A

E.
Corrode metal parts

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6
Q

Caution when burned the halocarbon refrigerants containing fluorine produce a very toxic _____ gas.
Select one:

A.
Mustard

B.
Carbon monoxide

C.
Phosgene

D.
Sulphur dioxide

E.
Hydrogen sulphide

A

C.
Phosgene

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7
Q

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:
Select one:

A.
Litmus paper

B.
A soap solution

C.
An electronic tester

D.
Water

E.
A halide torch

A

B.
A soap solution

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8
Q

Wetted litmus paper detects leaks in ammonia refrigeration systems by changing the colour of the litmus paper to a:
Select one:

A.
Light blue

B.
White

C.
Bright green

D.
Orange

E.
Reddish hue

A

E.
Reddish hue

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9
Q

During charging of the refrigeration system short cycling of the compressor should be avoided due to the starting stress which is placed on the:
Select one:

A.
Compressor valves

B.
Evaporator level control

C.
Compressor motor

D.
Expansion valve

E.
Condenser cooling water valve

A

A.
Compressor valves

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10
Q

The initial refrigerant charge is given on the _____ side of the system.
Select one:

A.
High-pressure

B.
Low-pressure

C.
Evaporator

D.
Expansion valve outlet

E.
Compressor inlet

A

A.
High-pressure

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11
Q

Ammonia leaks in refrigeration systems can also be detected by using a sulphur candle which, when lit, gives off a cloud of _____ smoke when exposed to ammonia fumes or vapour.
Select one:

A.
Reddish hue

B.
Light blue

C.
Bright green

D.
Orange

E.
White

A

E.
White

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12
Q

Just before charging an empty refrigerating system, the entire system should be:
Select one:

A.
Boiled out

B.
Pressure tested

C.
Put under a very high vacuum

D.
Hydro tested

E.
Pressures to the maximum allowable working pressure

A

C.
Put under a very high vacuum

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13
Q

As the pressurizing gas is admitted to the refrigeration system the pressure is first increased to the required:
Select one:

A.
High-pressure side maximum design pressure

B.
Low-pressure side minimum design pressure

C.
High-pressure side operating pressure

D.
Low-pressure side operating pressure

E.
High-pressure side minimum design pressure

A

B.
Low-pressure side minimum design pressure

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14
Q

Higher than normal head pressure is undesirable because of all of the following except it:
Select one:

A.
Over stresses the compressor parts

B.
Is detrimental to compressor valves and lubrication

C.
Reduces compressor capacity

D.
Creates lower evaporator pressure

E.
Increases power consumption

A

D.
Creates lower evaporator pressure

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15
Q

The refrigeration system condenser pressure should be slightly higher than the saturation pressure corresponding to the temperature of the refrigerant in the:
Select one:

A.
Upstream side of the compressor

B.
Condenser

C.
Accumulator

D.
Evaporator

E.
Downstream side of the expansion valve

A

B.
Condenser

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16
Q

Frost formation on the suction line in a _____ system may indicate overcharging.
Select one:

A.
Thermostatic expansion

B.
Low-pressure float

C.
Automatic expansion

D.
Capillary tube

E.
High-pressure float

A

D.
Capillary tube

17
Q

An alternate method to leak testing with a soap solution when using nitrogen is the:
Select one:

A.
Ultrasonic detector

B.
X-ray radiography

C.
Ultraviolet scanner

D.
Magnetic flux tester

E.
Infrared scanner

A

A.
Ultrasonic detector

18
Q

Overcharging a system causes _____ creating high compressor power consumption.
Select one:

A.
Low evaporator temperature

B.
High receiver temperature

C.
High condenser pressure

D.
Low suction evaporator pressure

E.
High compressor suction and discharge pressures

A

E.
High compressor suction and discharge pressures

19
Q

Regulations of the authority having jurisdiction may require that a _____ be reported.
Select one:

A.
Flush of the condenser

B.
Evacuation of the evaporator

C.
Loss of refrigerant

D.
Change of the compressor

E.
Loss of cooling water

A

C.
Loss of refrigerant

20
Q

Evacuation of the refrigeration system should not be attempted unless the temperature of the surrounding air is _____ or higher.
Select one:

A.
20°C (68°F)

B.
15°C (59°F)

C.
10°C (50°F)

D.
5°C (41°F)

E.
0°C (32°F)

A

A.
20°C (68°F)

21
Q

The pressurizing gas is admitted to the refrigeration system through the _____ valve.
Select one:

A.
Charging

B.
King

C.
Drain

D.
Queen

E.
Isolation

A

A.
Charging

22
Q

It may be illegal to _____ a refrigeration system without determining the location of and repairing the system leak.
Select one:

A.
Drain refrigerant from

B.
Evacuate the evaporator of

C.
Change the compressor of

D.
Flush the condenser of

E.
Simply add refrigerant to

A

E.
Simply add refrigerant to

23
Q

During the charging process the refrigerant that passes through the system is stored in liquid form in the:
Select one:

A.
Evaporator

B.
Compressor

C.
Receiver

D.
Expansion valve

E.
Chiller

A

C.
Receiver

24
Q

Purge systems are required on refrigeration systems that operate:
Select one:

A.
Below atmospheric pressure

B.
Below atmospheric temperature

C.
Above atmospheric temperature

D.
Only with ammonia as the refrigerant

E.
Without a qualified operator in attendance

A

A.
Below atmospheric pressure

25
Q

Positive pressure testing of a refrigeration system is done using dry _____ gas as the pressure agent.
Select one:

A.
Helium

B.
Oxygen

C.
Nitrogen

D.
Carbon monoxide

E.
Hydrogen sulphide

A

C.
Nitrogen

26
Q

In a process called “copper plating” the acids remove copper from heat exchanger surfaces and redeposit it at points of:
Select one:

A.
Low pressure

B.
High temperature

C.
High pressure

D.
Low temperature

E.
High flow

A

B.
High temperature

27
Q

Why should oxygen not be used to pressurize a system for leak checking purposes?
Select one:

A.
An external source of moisture free oxygen is required

B.
It could result in an explosion

C.
Oxygen is not compatible with refrigerants

D.
The oxygen combines with any non-condensable gases present to increase the system head pressure

E.
The oxygen can cause pitting of the parts of the system

A

B.
It could result in an explosion

28
Q

Once any leaks found in the system are repaired:
Select one:

A.
The system should be evacuated

B.
Refrigerant can be added to the system

C.
A second pressure test should be conducted

D.
The system is ready for operation

E.
The pressure can be released

A

C.
A second pressure test should be conducted

29
Q

The leakage of air into a refrigeration system that operates below atmospheric pressure will cause the _____ to cycle more often.
Select one:

A.
Evaporator level control

B.
Condenser cooling water regulator

C.
Compressor

D.
Purge unit

E.
Expansion valve

A

D.
Purge unit

30
Q

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:
Select one:

A.
Low-pressure side minimum design pressure

B.
High-pressure side maximum design pressure

C.
High-pressure side operating pressure

D.
High-pressure side minimum design pressure

E.
Low-pressure side operating pressure

A

D.
High-pressure side minimum design pressure

Second Half Book 2 (15 decks)

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