Cert III Air Conditioning & Refrigeration flashcards
Cert III Air Conditioning & Refrigeration · Build recall with a focused review session.
32 cards. Read the term and the definition here. The deck at the top of this page is optional.
- Hierarchy of control
- A ranked list of risk controls from most to least effective: eliminate, substitute, engineering controls, administrative controls, then personal protective equipment as the last resort.
- PCBU duty
- A person conducting a business or undertaking must ensure health and safety so far as reasonably practicable, including providing safe systems of work, training, supervision and monitoring.
- Refrigerant recovery
- The process of removing refrigerant from a system into a suitable container using recovery equipment, preventing release to atmosphere and allowing reuse, recycling or reclamation.
- Flashback arrestor
- A device fitted to oxy-fuel gas regulators and torches that stops a flame from travelling back into the hose or cylinder, preventing explosion during brazing work.
- Latent heat
- The heat energy absorbed or released when a substance changes phase at constant temperature, such as boiling liquid refrigerant into vapour in the evaporator.
- Superheat
- The difference between the actual suction line temperature and the saturation temperature at suction pressure; it confirms the evaporator is fully flooded with liquid.
- Subcooling
- The difference between the condensing saturation temperature and the liquid line temperature; it confirms the condenser has condensed all refrigerant and the liquid is solid.
- Compression ratio
- Absolute discharge pressure divided by absolute suction pressure; high ratios increase discharge temperature and reduce volumetric efficiency, affecting compressor reliability.
- Temperature glide
- The temperature change during phase change for a zeotropic blend; superheat uses dew point and subcooling uses bubble point to account for this range.
- Dew point
- The temperature at which air becomes saturated and water vapour begins to condense; cooling below dew point produces condensate on coils and ducts.
- Ohm's law
- The relationship V = I × R, where voltage equals current multiplied by resistance; used to calculate expected readings when testing electrical circuits and components.
- Power factor
- The ratio of real power to apparent power in an AC circuit; single-phase power equals voltage times current times power factor.
- Contactor
- An electrically operated switch that uses a coil to close heavy-duty contacts, supplying power to compressors, fans and heaters under control circuit command.
- Thermal overload
- A protection device that trips when motor current exceeds a set value for a set time, preventing winding damage from sustained overcurrent or overheating.
- Phase rotation
- The order in which three-phase voltages reach their peaks; incorrect rotation reverses scroll and screw compressor direction, causing damage and no pumping.
- Defrost termination
- A sensor and control that ends the defrost cycle when the coil reaches a set temperature or pressure, preventing overheating and excess energy use.
- Triple evacuation
- A commissioning method using repeated evacuation with dry nitrogen breaks to remove moisture and non-condensables, confirmed by a micron gauge holding below 500 microns.
- Nitrogen purge
- A flow of dry nitrogen through the pipework during brazing that displaces oxygen and prevents internal oxidation scale from forming inside the refrigerant circuit.
- Pressure testing
- A strength and leak test using dry nitrogen at the specified test pressure, held and recorded; oxygen and air must never be used on a refrigerant circuit.
- Charge by weight
- Adding refrigerant measured on scales to the manufacturer's specified mass; blends must be charged as liquid to avoid fractionation and incorrect composition.
- Air balancing
- Adjusting dampers and fan speeds to deliver design airflow to each zone, verified by measuring air quantities and static pressures during commissioning.
- High superheat fault
- A reading above design superheat with low suction pressure, indicating undercharge, a liquid line restriction, or an expansion valve that is underfeeding.
- Low superheat fault
- A reading below design superheat with high suction pressure, indicating overcharge or an overfeeding valve; liquid floodback can damage the compressor.
- High discharge pressure
- A discharge pressure above normal, caused by poor condenser airflow, fouled coils, non-condensables, or high ambient temperature; it raises current draw and trip risk.
- Sight glass moisture
- An indicator in the liquid line that changes colour when moisture is present, signalling the need for evacuation, filter drier replacement or leak investigation.
- Leak detection
- Locating refrigerant loss using electronic detectors, soap bubbles, pressure decay or UV dye; the leak is repaired before the system is recharged.
- Decommissioning
- The controlled removal of a system from service: isolate power, recover refrigerant, purge and cap lines, remove and dispose of oil and components as regulated waste.
- Oil condition check
- Inspecting compressor oil level and colour; dark or acidic oil indicates overheating, moisture or burnout and requires oil change and system clean-up.
- Refrigerant record
- A log of refrigerant purchased, used, recovered and disposed of, with dates and equipment identifiers, required for environmental compliance and audit.
- Job service report
- A written record of the site, equipment, refrigerant charge, measured readings, work performed, parts used and recommended follow-up, given to the customer.
- Refrigerant handling licence
- The national credential required to buy, handle, recover or dispose of refrigerants; electrical work on refrigeration plant requires a separate electrician licence.
- Safe work method statement
- A document that sets out the high-risk work steps, hazards, controls and responsible persons, reviewed with the team before work begins.