C&G 2079-11 F-Gas Cat I Exam Flashcards

Q: What is the pass mark for the C&G 2079-11 F-Gas Category I exam?

You need 60% on the 40-question multiple-choice theory paper (24 correct answers) within 80 minutes, plus a pass in the separate practical assessment. Both elements must be achieved; the qualification is graded Pass/Fail.

Q: What does F-Gas Category I let a technician do?

Category I is the broadest UK F-Gas certificate: it legally permits leak checking, refrigerant recovery, installation, servicing and maintenance on stationary refrigeration, air-conditioning and heat-pump equipment of any refrigerant charge size.

Q: Does the F-Gas Regulation still apply in Great Britain after Brexit?

Yes. EU Regulation 517/2014 (the F-Gas Regulation) continues to apply in Great Britain as retained EU law, implemented domestically through the Fluorinated Greenhouse Gases Regulations 2015 (SI 2015/310, as amended).

Q: What are the statutory leak-check thresholds I need to know?

Frequency is set by CO2 equivalent charge: 5 to under 50 tonnes = 12-monthly, 50 to under 500 tonnes = 6-monthly, 500 tonnes or more = 3-monthly with a mandatory fixed leak-detection system. A fitted fixed detector doubles the check interval below 500 tonnes.

Q: How should I use these F-Gas flashcards?

Drill the exact numbers (GWP values, leak-check bands, the 5 g/year detector sensitivity, the 80% cylinder fill limit) until they're automatic, then pair them with our free practice questions and AI tutor to confirm understanding before your assessed course exam.

Question 1

What are the four main components of the basic vapour-compression refrigeration cycle?

Accepted Answer

Compressor, condenser, expansion device (valve or capillary), and evaporator, connected in a closed loop the refrigerant circulates through repeatedly.

Question 2

What happens to refrigerant inside the evaporator?

Accepted Answer

Low-pressure liquid refrigerant boils, absorbing latent heat of vaporisation from the surrounding air or product - this phase change produces the system's cooling effect.

Question 3

What is the compressor's role in the refrigeration cycle?

Accepted Answer

It draws in low-pressure vapour from the evaporator and raises its pressure and temperature, adding the work needed so the vapour can reject heat in the condenser.

Question 4

What happens to refrigerant in the condenser?

Accepted Answer

Hot, high-pressure superheated vapour from the compressor is de-superheated and then condensed to liquid, rejecting heat to ambient air or water; total heat rejected equals the cooling load plus compressor work.

Question 5

What happens to refrigerant pressure and temperature across the expansion device?

Accepted Answer

Both fall sharply as the device throttles high-pressure liquid to low pressure. The process is isenthalpic (constant enthalpy), shown as a vertical line on a p-h diagram.

Question 6

Define 'superheat'.

Accepted Answer

The number of degrees a refrigerant vapour is heated above its saturation (boiling) temperature at the prevailing pressure. Adequate suction superheat protects the compressor from liquid floodback/slugging.

Question 7

Define 'sub-cooling'.

Accepted Answer

Cooling liquid refrigerant below its saturation temperature at the prevailing pressure, typically at the condenser outlet, ensuring only liquid (not flash gas) reaches the expansion device.

Question 8

On a pressure-enthalpy (p-h) diagram, what does the area inside the saturation dome represent?

Accepted Answer

The two-phase region where liquid and vapour coexist. To the left of the dome is sub-cooled liquid; to the right is superheated vapour; evaporation and condensation both occur inside the dome at constant pressure.

Question 9

Why must liquid refrigerant never return to the compressor suction?

Accepted Answer

Liquid is effectively incompressible, so it can cause hydraulic shock ('liquid slugging') that damages valves and bearings; maintaining correct suction superheat prevents this floodback.

Question 10

What is the legal basis of the F-Gas Regulation in Great Britain since Brexit?

Accepted Answer

EU Regulation 517/2014 (the F-Gas Regulation) continues to apply in GB as retained EU law, implemented domestically through the Fluorinated Greenhouse Gases Regulations 2015 (SI 2015/310, as amended).

Question 11

How is a refrigerant charge's CO2 equivalent (CO2e) calculated?

Accepted Answer

CO2 equivalent = charge mass in tonnes x the refrigerant's GWP. Example: 10 kg (0.01 t) of R-404A (GWP ~3922) equals about 39 tonnes CO2e. This figure sets the statutory leak-check interval.

Question 12

What HFC service ban took effect on 1 January 2020?

Accepted Answer

It became illegal to use virgin HFCs with a GWP of 2500 or more (e.g. R-404A) to service or maintain equipment with a charge of 40 tonnes CO2 equivalent or more; reclaimed or recycled refrigerant remained permitted under conditions.

Question 13

What is the F-Gas Regulation's 'HFC phase-down'?

Accepted Answer

A quota system that steadily cuts the total CO2-equivalent tonnage of HFCs allowed onto the market, falling to about one-fifth of the 2015 baseline by 2030, driving uptake of lower-GWP and natural refrigerants.

Question 14

How do CFCs, HCFCs, HFCs and HFOs differ from each other?

Accepted Answer

CFCs and HCFCs contain chlorine and deplete ozone (ODP > 0); HFCs contain no chlorine (ODP = 0) but many have high GWP; HFOs (e.g. R-1234yf) are unsaturated HFC-type gases with near-zero GWP and ODP = 0.

Question 15

Is it ever legal to deliberately vent (release) F-gases to atmosphere?

Accepted Answer

No. Deliberate release of fluorinated greenhouse gases is prohibited under the F-Gas Regulation; refrigerant must always be recovered by certified personnel.

Question 16

What does an F-Gas Category I certificate authorise a technician to do?

Accepted Answer

It is the broadest UK F-Gas tier: leak checking, refrigerant recovery, installation, servicing and maintenance on stationary refrigeration, air-conditioning and heat-pump equipment of ANY refrigerant charge size.

Question 17

What F-gas records must an operator keep, and for how long?

Accepted Answer

The type and quantity of F-gas installed, added and recovered, the dates and results of leak checks, and the identity of the technician or company that did the work - retained for at least 5 years.

Question 18

Who is the legally responsible 'operator' under the F-Gas Regulation?

Accepted Answer

The person or company with actual power over the technical functioning of the equipment (usually the owner or site manager) - they must arrange leak checks, repairs, recovery and record keeping via certified technicians.

Question 19

Why must a zeotropic blend (e.g. R-407C, R-404A) be charged into a system as a liquid rather than a vapour?

Accepted Answer

Its components have different boiling points; vapour charging would draw off the lighter components first and change the blend's composition (fractionation). Liquid charging keeps the mix correct.

Question 20

What is 'temperature glide' in a zeotropic blend, and how does an azeotropic blend differ?

Accepted Answer

Glide is evaporation/condensation occurring across a range of temperatures at constant pressure, seen in zeotropic blends. Azeotropic blends (e.g. R-507A) behave like a single substance with negligible glide.

Question 21

What does a thermostatic expansion valve (TEV/TXV) do?

Accepted Answer

It uses a sensing bulb on the suction line to modulate liquid flow into the evaporator, maintaining a target superheat and protecting the compressor from liquid floodback.

Question 22

What is the purpose of a filter drier in a refrigeration circuit?

Accepted Answer

It removes moisture, acids and solid contaminants from the circulating refrigerant using a desiccant and filter, preventing ice formation at the expansion device and protecting the compressor.

Question 23

What does continuous bubbling in the liquid-line sight glass usually indicate during steady running?

Accepted Answer

Flash gas in the liquid line, typically caused by an undercharge or a restriction reducing sub-cooling. A clear sight glass with adequate sub-cooling indicates a correctly charged liquid line.

Question 24

What is the function of a liquid receiver?

Accepted Answer

Fitted after the condenser, it stores surplus liquid refrigerant, accommodates changes in charge demand as load varies, and provides a place to pump down the system charge during service.

Question 25

What is a manifold gauge set used for?

Accepted Answer

Reading high-side (red) and low-side (blue) system pressures and controlling refrigerant flow during evacuation, charging and recovery; its saturation scales relate pressure to temperature for setting superheat and sub-cooling.

Question 26

Why is a system evacuated with a vacuum pump before charging?

Accepted Answer

To remove air, moisture and other non-condensables - moisture forms acids and ice at the expansion device, and trapped air raises head pressure. Systems are typically pulled to a deep, stable vacuum (around 500 microns).

Question 27

Why must refrigerant added during charging be measured on accurate weighing scales?

Accepted Answer

Charge is specified by mass, so accurate weighing ensures the correct charge for proper performance, and the quantity added must be recorded to meet F-Gas record-keeping duties.

Question 28

How often must equipment with 5 to under 50 tonnes CO2 equivalent (no fixed leak detector) be leak checked?

Accepted Answer

At least every 12 months.

Question 29

How often must equipment with 50 to under 500 tonnes CO2 equivalent (no fixed leak detector) be leak checked?

Accepted Answer

At least every 6 months.

Question 30

How often must equipment with 500 tonnes CO2 equivalent or more be leak checked, and what else is required at this band?

Accepted Answer

At least every 3 months, AND a fixed (automatic) leak-detection system is mandatory at 500 tonnes CO2 equivalent or more.

Question 31

How does fitting a fixed (automatic) leak-detection system change the statutory leak-check interval?

Accepted Answer

It doubles the interval for the charge band below 500 tonnes: 5 t band becomes 24-monthly, 50 t band becomes 12-monthly. A fixed detector is itself mandatory (not optional) at 500 t or more.

Question 32

When is hermetically sealed equipment exempt from routine leak checks?

Accepted Answer

Only when it is labelled as hermetically sealed AND contains less than 10 tonnes CO2 equivalent. Non-hermetic equipment loses any exemption at 5 tonnes CO2 equivalent.

Question 33

What sensitivity must an electronic refrigerant leak detector achieve, and how often must it be checked?

Accepted Answer

It must be capable of detecting a leak rate of 5 grams per year or less, and must be checked/calibrated at least every 12 months to maintain that sensitivity.

Question 34

What is the difference between direct and indirect leak-detection methods?

Accepted Answer

Direct methods find the escaping gas itself (electronic sniffer, UV dye and lamp, bubble/soap solution). Indirect methods infer a leak from operating parameters (pressures, temperatures, refrigerant levels). Halide torches do not respond to chlorine-free HFCs, so they are unsuitable for modern refrigerants.

Question 35

What must happen within one month of repairing a detected refrigerant leak?

Accepted Answer

A certified technician must carry out a follow-up check to verify the repair was effective and the system is no longer leaking.

Question 36

What does 'recovery' mean under the F-Gas Regulation?

Accepted Answer

Capturing and storing refrigerant from equipment, such as during servicing or decommissioning, into a suitable recovery cylinder instead of releasing it. Recovery by a certified technician is required before disposal or opening a circuit.

Question 37

What is the difference between recycling and reclaiming recovered refrigerant?

Accepted Answer

Recycling is a basic clean-up (filtering/drying) allowing reuse, often on similar equipment on site. Reclamation reprocesses recovered refrigerant (distillation/chemical treatment) and tests it to a specification such as AHRI 700 so it can be resold as virtually new.

Question 38

Why must a recovery cylinder never be filled beyond about 80% of its capacity with liquid refrigerant?

Accepted Answer

To leave an ullage (vapour) space of roughly 20% for liquid expansion. Overfilling a cylinder so it becomes liquid-full risks dangerous hydraulic over-pressure and rupture.

Question 39

Why must different refrigerants be recovered into separate, clearly labelled cylinders?

Accepted Answer

Mixing refrigerant types cross-contaminates them so they can no longer be recycled or reclaimed and must instead be destroyed, which is costly and wasteful.

Question 40

Is it ever legal to vent refrigerant to atmosphere instead of recovering it, even for a small charge?

Accepted Answer

No. Deliberate release (venting) of F-gases is illegal regardless of charge size because they are potent greenhouse gases; refrigerant must always be recovered into a suitable cylinder.

Question 41

What happens to recovered refrigerant that is too contaminated to recycle or reclaim?

Accepted Answer

It must be sent for destruction (e.g. high-temperature incineration) at a licensed facility rather than reused or released.

Question 42

What does GWP (Global Warming Potential) measure, and what is the reference value?

Accepted Answer

How much heat a greenhouse gas traps over 100 years relative to the same mass of CO2, which is defined as GWP = 1. A higher GWP means greater climate impact per kilogram released.

Question 43

What does ODP (Ozone Depletion Potential) measure, and which refrigerant families have ODP greater than zero?

Accepted Answer

A substance's ability to destroy stratospheric ozone relative to R-11 (ODP = 1). Only chlorine-containing CFCs and HCFCs have ODP > 0; HFCs and HFOs have ODP = 0.

Question 44

What did the 1987 Montreal Protocol establish?

Accepted Answer

The international treaty that controls and phases out ozone-depleting substances, including CFCs and HCFCs.

Question 45

What does the 2016 Kigali Amendment to the Montreal Protocol add?

Accepted Answer

A global commitment to phase down high-GWP hydrofluorocarbons (HFCs) - gases that do not deplete ozone but are potent greenhouse gases.

Question 46

What are the approximate AR4 GWP values (used in F-Gas CO2e calculations) for R-410A, R-32, R-134a, R-1234yf, CO2 (R-744) and ammonia (R-717)?

Accepted Answer

R-410A ~2088, R-32 ~675, R-134a ~1430, R-1234yf <1, CO2 (R-744) = 1 (the reference gas), ammonia (R-717) = 0.

Question 47

Which UK Act places a general duty on employers and employees to ensure health and safety at work, including safe refrigerant handling?

Accepted Answer

The Health and Safety at Work etc. Act 1974 (HASAWA).

Question 48

What do the COSHH Regulations require when handling refrigerants and lubricating oils?

Accepted Answer

Employers must assess and control exposure to substances hazardous to health (e.g. via ventilation, PPE and safe systems of work), supported by safety data sheets.

Question 49

Why is oxygen-free nitrogen (OFN) used both for purging during brazing and for pressure (strength) testing?

Accepted Answer

It is dry and chemically inert: purging with OFN while brazing prevents internal copper oxide scale forming, and using it for pressure testing avoids introducing moisture or reacting with oil. Oxygen or compressed air must never be used for either task.

Question 50

What PPE hazards apply when handling liquid refrigerant, and what other risk exists from a large leak in an unventilated space?

Accepted Answer

Liquid refrigerant causes cold (frost) burns and eye injury on contact, so gloves and eye/face protection are required. A large leak of heavier-than-air refrigerant can also displace oxygen at low level, creating an asphyxiation risk.

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