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Air Con > F-Gas Exam > Flashcards

F-Gas Exam Flashcards

1
Q

What best describes enthalpy?

A

Heat content per unit mass - KJ/Kg

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2
Q

What is the function of an evaporative condenser?

A

To reject latent heat to change vapour to liquid

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3
Q

What will provide the sight glass with a clear liquid line?

A

Sub-cooled liquid

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4
Q

What does the Kyoto protocol cover?

A

Climate Change

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5
Q

What refrigerant is most likely to suffer from changes in its composition after leakage?

A

R407c - Zeotrope Refrigerant blend

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6
Q

Energy efficient ration of a heat pump system is?

A

Heating capacity over Total system input power

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7
Q

As the difference between condensing temperature decreases what happens?

A

Work done decreases and discharge temperature decreases

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8
Q

What qualification is required to recover refrigerant from an A/C system which has a charge of 7.5kg of R407c

A

F Gas Qualification 1

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9
Q

BS EN 378 Requires the saturation temperature of what?

A

55 Degrees

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10
Q

What is most likely to increase refrigerant leakage potential from an air to water heat pump?

A

Excessive discharge vapour superheat

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11
Q

The function of the compressor is what?

A

To circulate refrigerant vapour and increase pressure

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12
Q

Compressor being too hot to touch on a blast freeze system indicates what?

A

Motor failure

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13
Q

What would run with the lowest condensing temperature?

A

Evaporative condenser

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14
Q

A Clean condenser on an A/C System leads to what?

A

A Lower discharge pressure and higher efficiency

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15
Q

When every one degrees celsius that the evaporating temperature is increased….

A

Cooling capacity is increased by 3% and energy use decreased by 3%

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16
Q

What is most likely to cause the evaporator of an unprotected water chiller to freeze solid?

A

Lower than normal waterside temperature

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17
Q

What is the function of an expansion valve?

A

To control refrigerant flow and decrease pressure

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18
Q

What setting is most likely to cause a system hermetic compressor to run continuously and over heat?

A

20K Thermostatic Expansion Valve superheat setting

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19
Q

R22 is classified as a what?

A

Ozone depleting substance

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20
Q

Montreal protocol is the international agreement responsible for what?

A

The phase out of HCFC’s (hydro-chloro-fluoro-carbon)

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21
Q

What is the refrigerant hazard that can make an affected person feel ‘high’?

A

Central Nervous System effect

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22
Q

Why must residual flux be removed from the outside of a brazed copper pipe?

A

Because it absorbs water from the air and corrodes the pipe.

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23
Q

What pipe diameter is the most likely to fail when strength tested with OFN?

A

4 1/8

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24
Q

GWP of R4O4a

A

3922

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25
Q

GWP of R410a

A

2088

26
Q

GWP of R22

A

1810

27
Q

GWP of R245 fa

A

1030

28
Q

GWP of R123

A

120

29
Q

GWP of R600a / R290

A

3

30
Q

GWP of HF01234 yf

A

4

31
Q

GWP of R717 (Ammonia)

A

0

32
Q

Condensing, Compression, Evaporation then?

A

Expansion

33
Q

COP =

A

Refrigeration effect over Compressor work done

34
Q

EER Cooling

A

total cooling capacity over total system power input

35
Q

EER Heating

A

total heating capacity over total system power input

36
Q

Subcooling is established when?

A

Refrigerant liquid is cooled below its boiling point

37
Q

An A/C System with a pipe run of 40% of its max pre charge will have refrigerant in what state in the suction line accumulator?

A

Saturated two phase mixture

38
Q

What would allow an engineer to connect refrigerant gauges to a system with minimum refrigerant loss?

A

Service valve back seated

39
Q

What is the purpose of a TEV (Thermostatic Expansion Valve)

A

To maintain a constant superheat

40
Q

A System with a capillary tube restrictor will?

A

Allow pressures to equalise in off cycle

41
Q

A Clear sight glass and high superheat would indicate what?

A

The TEV is undersized

42
Q

TEV Bulb which has come adrift from the suction line will have what effect

A

Decrease superheat

43
Q

What direction is the most desirable for mounting a condensing unit?

A

North Facing

44
Q

The montreal protocol deals with?

A

Ozone Depletion

45
Q

E.C. Regulation 2037/2000 relates to?

A

CFC’s and HCFC’s

46
Q

What refrigerant is subject to controls in relation to E.C. Regulation 2037/2000

A

R22 - HCFC

47
Q

What poses the greatest risk of fire?

A

HC - Hydrocarbon

48
Q

When the MAP pressure for a refrigerant is 34 Bar what is the safest regulator to use for strength testing?

A

50 Bar - MAP X by 1.43

49
Q

The purpose of a vac pump is to?

A

1 - Evacuate the system of non - condensables
2- Reduce the pressure in the pipework below atmospheric pressure
3- To Cause moisture to evaporate

50
Q

The state of the refrigerant leaving a capillary tube restrictor/expansion device entering an evaporator would be?

A

Saturated mixture at low temperature and low pressure

51
Q

A Superheated vapour is

A

Heated above its Saturated temperature

52
Q

A change of state with no change of temperature is called?

A

Latent

53
Q

A Change of temperature with no change of state is called?

A

Sensible

54
Q

If heat is added to a saturated liquid what will be the effect?

A

It starts to boil to a vapour

55
Q

What should you vacuum a system down to?

A

2000 microns

56
Q

To keep the condenser pressure within manufacturers guidelines you should?

A

Reduce fan speed on high pressure

57
Q

Which compressor is least likely to leak?

A

Hermetic

58
Q

Which cleaning method is most damaging to a fin-coil condenser?

A

Acid-based cleaner

59
Q

GWP of R32

A

675

60
Q

GWP of R1234 ze

A

6

Air Con (2 decks)

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