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Elements and Performance Criteria

1. Prepare to service CO² refrigeration system
   • WHS/OHS hazards, risk control methods, relevant standards, codes and legislation are obtained and applied
2. Safety hazards not previously identified are assessed, reported and advice on risk control measures sought from work supervisor
3. Nature of refrigeration work is obtained from documentation or from work supervisor to determine the scope of refrigeration work to be undertaken
4. Advice is sought from work supervisor to ensure refrigeration work is coordinated effectively with others
5. Sources of materials required for the 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 CO² refrigeration system
   • Measuring refrigeration system operating parameters is conducted in accordance with WHS/OHS requirements and workplace safety procedures
8. Inspection and checks are carried out to ensure the refrigeration system or component parts are isolated in accordance with WHS/OHS requirements, industry standards and practices
9. Refrigerant is removed from refrigeration system safely in accordance with WHS/OHS requirements, industry standards and practices
10. Precautions are taken to prevent damage to components while pressure testing refrigeration system
11. Pressure testing is conducted at a pressure compatible with CO² and in accordance with WHS/OHS requirements, industry standards and practices
12. Leaks are located and rectified using testing methods appropriate to the refrigeration system and in accordance with industry standards and practices
13. Refrigeration system is evacuated to the required level and cleaned of moisture and other contaminants in accordance with industry standards and practices
14. Refrigeration 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 sub-critical CO² vapour compression and liquid recirculation/cascade systems in accordance with workplace procedures
16. Unplanned situations are responded to and discussed with appropriate person/s and documented in accordance with workplace procedures in a manner that minimises risk to personnel and equipment
17. Refrigeration operating conditions are determined without damage to apparatus, circuits, the surrounding environment or services using sustainable energy practices
18. Complete work and report on servicing CO² refrigeration system
    • Worksite is cleaned and made safe in accordance with workplace procedures
19. Contaminated refrigerant and lubricant are dealt with in accordance with legislative/regulatory requirements
20. Operation conditions are documented and include identification of any parameters that are not within the specified range for the refrigeration system
21. Work supervisor is notified of the completion of work in accordance with established 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 CO² refrigeration systems must include at least the following:	charging and discharging a CO² system with refrigerant and lubricant in a safe and environmentally responsible manner, excluding self-contained systems determining: suction and discharge pressures ambient, evaporator and condensing temperatures evaporator and condenser temperature difference critical point, triple point, trans-critical and sub-critical refrigerant conditions

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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 legislative, 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 completing work and reporting on servicing and repairing sub-critical carbon dioxide (CO²) refrigeration systems conducting work observing the relevant legislation, regulations, polices and workplace procedures dealing with unplanned events/situations in accordance with workplace procedures in a manner that minimises risk to personnel and equipment decontaminating and evacuating the system discharging/charging refrigerant/lubricants and pressure testing the system without damage to components documenting operating conditions correctly identifying the conditions of the CO² refrigerant at various locations in the vapour compression and volatile secondary (liquid recirculation) system locating and rectifying leaks preparing to service and repair CO² refrigeration systems pressure testing, charging/discharging refrigerant/lubricants and determining the operating conditions of CO² vapour compression and volatile secondary (liquid recirculation) system recording measurements selecting and using appropriate measuring devices correctly servicing and repairing CO² refrigeration systems 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 systems, including: basic CO² refrigeration system basic liquid recirculation /cascade system employing CO² refrigerant at sub-critical condition benefits of using CO² as a refrigerant thermophysical properties operating conditions of CO² refrigeration systems, including: applicable standards and codes CO² refrigeration compressors and lubricants system components, construction and operation servicing and repair techniques for CO² refrigeration systems, including: moisture problems with CO² systems refrigerant conditions refrigerant cylinders and regulators service gauges service procedures system standing pressure as a result of power loss.

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