F-Gas Exam Flashcards
What best describes enthalpy?
Heat content per unit mass - KJ/Kg
What is the function of an evaporative condenser?
To reject latent heat to change vapour to liquid
What will provide the sight glass with a clear liquid line?
Sub-cooled liquid
What does the Kyoto protocol cover?
Climate Change
What refrigerant is most likely to suffer from changes in its composition after leakage?
R407c - Zeotrope Refrigerant blend
Energy efficient ration of a heat pump system is?
Heating capacity over Total system input power
As the difference between condensing temperature decreases what happens?
Work done decreases and discharge temperature decreases
What qualification is required to recover refrigerant from an A/C system which has a charge of 7.5kg of R407c
F Gas Qualification 1
BS EN 378 Requires the saturation temperature of what?
55 Degrees
What is most likely to increase refrigerant leakage potential from an air to water heat pump?
Excessive discharge vapour superheat
The function of the compressor is what?
To circulate refrigerant vapour and increase pressure
Compressor being too hot to touch on a blast freeze system indicates what?
Motor failure
What would run with the lowest condensing temperature?
Evaporative condenser
A Clean condenser on an A/C System leads to what?
A Lower discharge pressure and higher efficiency
When every one degrees celsius that the evaporating temperature is increased….
Cooling capacity is increased by 3% and energy use decreased by 3%
What is most likely to cause the evaporator of an unprotected water chiller to freeze solid?
Lower than normal waterside temperature
What is the function of an expansion valve?
To control refrigerant flow and decrease pressure
What setting is most likely to cause a system hermetic compressor to run continuously and over heat?
20K Thermostatic Expansion Valve superheat setting
R22 is classified as a what?
Ozone depleting substance
Montreal protocol is the international agreement responsible for what?
The phase out of HCFC’s (hydro-chloro-fluoro-carbon)
What is the refrigerant hazard that can make an affected person feel ‘high’?
Central Nervous System effect
Why must residual flux be removed from the outside of a brazed copper pipe?
Because it absorbs water from the air and corrodes the pipe.
What pipe diameter is the most likely to fail when strength tested with OFN?
4 1/8
GWP of R4O4a
3922
GWP of R410a
2088
GWP of R22
1810
GWP of R245 fa
1030
GWP of R123
120
GWP of R600a / R290
3
GWP of HF01234 yf
4
GWP of R717 (Ammonia)
0
Condensing, Compression, Evaporation then?
Expansion
COP =
Refrigeration effect over Compressor work done
EER Cooling
total cooling capacity over total system power input
EER Heating
total heating capacity over total system power input
Subcooling is established when?
Refrigerant liquid is cooled below its boiling point
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?
Saturated two phase mixture
What would allow an engineer to connect refrigerant gauges to a system with minimum refrigerant loss?
Service valve back seated
What is the purpose of a TEV (Thermostatic Expansion Valve)
To maintain a constant superheat
A System with a capillary tube restrictor will?
Allow pressures to equalise in off cycle
A Clear sight glass and high superheat would indicate what?
The TEV is undersized
TEV Bulb which has come adrift from the suction line will have what effect
Decrease superheat
What direction is the most desirable for mounting a condensing unit?
North Facing
The montreal protocol deals with?
Ozone Depletion
E.C. Regulation 2037/2000 relates to?
CFC’s and HCFC’s
What refrigerant is subject to controls in relation to E.C. Regulation 2037/2000
R22 - HCFC
What poses the greatest risk of fire?
HC - Hydrocarbon
When the MAP pressure for a refrigerant is 34 Bar what is the safest regulator to use for strength testing?
50 Bar - MAP X by 1.43
The purpose of a vac pump is to?
1 - Evacuate the system of non - condensables
2- Reduce the pressure in the pipework below atmospheric pressure
3- To Cause moisture to evaporate
The state of the refrigerant leaving a capillary tube restrictor/expansion device entering an evaporator would be?
Saturated mixture at low temperature and low pressure
A Superheated vapour is
Heated above its Saturated temperature
A change of state with no change of temperature is called?
Latent
A Change of temperature with no change of state is called?
Sensible
If heat is added to a saturated liquid what will be the effect?
It starts to boil to a vapour
What should you vacuum a system down to?
2000 microns
To keep the condenser pressure within manufacturers guidelines you should?
Reduce fan speed on high pressure
Which compressor is least likely to leak?
Hermetic
Which cleaning method is most damaging to a fin-coil condenser?
Acid-based cleaner
GWP of R32
675
GWP of R1234 ze
6
