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

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

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.

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.

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.

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.

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.

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.

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.

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

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).

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.

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.

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.

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.

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

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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).

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.

At least every 12 months.

At least every 6 months.

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

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.

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.

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.

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.

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

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.

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.

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.

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.

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.

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

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.

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.

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

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

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

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

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.

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.

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.