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Elements and Performance Criteria

1. Prepare to service self-contained CO² refrigeration and heat pump system
   • WHS/OHS hazards, risk control methods, relevant standards, codes and legislation are obtained and applied
2. Safety hazards not previously identified are reported, risk assessed and advice on risk control measures sought from work supervisor
3. Nature of work is obtained from documentation or from work supervisor to determine the scope of work to be undertaken
4. Advice is sought from work supervisor to ensure the work is coordinated effectively with others
5. Sources of materials required for the refrigeration work are accessed in accordance with workplace and procedures
6. Tools, equipment and testing devices needed to carry out refrigeration work are obtained and checked for correct operation and safety
7. Service and repair self-contained CO² refrigeration and heat pump system
   • Measuring system operating parameters are conducted in accordance with WHS/OHS requirements and workplace safety procedures
8. Refrigeration inspection and checks are carried out to ensure the system or component parts are isolated in accordance with WHS/OHS requirements and workplace procedures
9. Refrigerant is removed from system safely in accordance with regulatory requirements, industry standards and practices
10. Precautions are taken to prevent damage to components while pressure testing the refrigeration and heat pump system
11. Pressure testing is conducted at a pressure compatible with CO² and in accordance with industry standards and practices
12. Refrigerant leaks are located and rectified using testing methods appropriate to the system and in accordance with industry standards and practices
13. Refrigeration and heat pump system is evacuated to the required level and cleaned of all moisture and other contaminants in accordance with industry standards and practices
14. Refrigeration and heat pump system is charged safely with refrigerant grade CO² and compatible lubricants in accordance with industry standards and practices
15. Actual and specified range of operating conditions are determined from measured and calculated values as they apply to CO² vapour compression systems in accordance with workplace procedures and industry standards
16. Unplanned situations are dealt with safely and in accordance with workplace procedures and approval of authorised person/s in a manner that minimises risk to personnel and equipment
17. Operating conditions are determined without damage to apparatus, circuits, the surrounding environment or services using sustainable energy practices
18. Complete and report servicing and repair of self-contained CO² refrigeration and heat pump system work activities
    • Worksite is cleaned and made safe in accordance with workplace procedures
19. Contaminated refrigerant and lubricant are dealt with in accordance with legislative/regulatory and industry standard requirements
20. Operation conditions are documented and include identification of any parameter that is not within the specified range for the system
21. Work supervisor is notified of the completion of work in accordance with workplace procedures

Range Statement

Range is restricted to essential operating conditions and any other variables essential to the work environment. Non-essential conditions may be found in the UEE Electrotechnology Training Package Companion Volume Implementation Guide.

Servicing and repairing self-contained CO² vapour compression systems must include at least the following:

domestic refrigerators and freezers refrigerated cabinets heat pumps water heaters checking: suction and discharge pressures ambient, evaporator and condensed/gas cooler temperatures evaporator and gas cooler temperature difference critical point, triple point and trans-critical and sub-critical refrigerant conditions of CO² charging and discharging trans-critical CO² system with refrigerant and lubricant in a safe and environmentally responsible manner

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Performance Evidence

Evidence required to demonstrate competence in this unit must be relevant to and satisfy all of the requirements of the elements, performance criteria and range of conditions on at least two separate occasions and include:

applying relevant legislation, industry standards and practices applying relevant work health and safety (WHS)/occupational health and safety (WHS/OHS) requirements and workplace procedures and practices, including using risk control measures applying sustainable energy principles and practices dealing with unplanned events/situations in accordance with workplace procedures in a manner that minimises risk to personnel and equipment discharging/charging refrigerant/lubricants and pressure testing the system without damage to components documenting operating conditions correctly identifying the conditions of the carbon dioxide (CO²) refrigerant at various locations in the vapour compression system in a trans-critical and sub-critical state locating and rectifying leaks pressure testing, evacuating, charging/discharging refrigerant/lubricants and determining the operating conditions of CO² vapour compression systems recording measurements selecting and using appropriate measuring devices correctly using calculation methods accurately.

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Knowledge Evidence

Evidence required to demonstrate competence in this unit must be relevant to and satisfy all of the requirements of the elements, performance criteria and range of conditions and include knowledge of:

CO² refrigeration compressors and lubricants, including: types, construction and their applications types of compatible compressor oil (Polyolester (POE) and Polyaphalefin (PAO)) safe handling of lubricants for CO² applications using safety data sheets (SDS)/material safety data sheets (MSDS) cylinder regulators moisture problems with CO² systems refrigerant CO² cylinders and regulators refrigerant conditions refrigeration principles relevant industry standards, codes and practices relevant job safety assessments or risk mitigation processes, including hazards associated with CO² relevant manufacturer specifications relevant WHS/OHS legislated requirements relevant workplace documentation, including service manuals and service documentation relevant workplace policies and procedures self-contained systems employing CO² refrigerant at trans-critical condition, including: basic operation domestic refrigerators and freezers heat pumps water heaters refrigerated cabinets systems and major components typical applications service gauges service procedures CO² refrigerant, including: benefits of using CO² as a refrigerant thermophysical properties servicing tools, equipment and safe working procedures, including: cylinder regulators moisture problems with CO² systems refrigerant CO² cylinders and regulators refrigerant conditions service gauges service procedures system standing pressure as a result of power loss system components, construction and operation, including: capillary tubes and accurators CO² evaporator design features CO² sub-cooler design features electronic expansion valves liquid-suction heat exchangers pressure relief devices refrigerant flow controls system standing pressure as a result of power loss. trans-critical CO² refrigeration and heat pump systems.

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