Elements and Performance Criteria

Context
This competency unit includes items of equipment such as:
large refrigeration systems that produce low temperatures
multi-stage centrifugal compressors
heat exchangers.

Typical problems include:
maintaining required operating temperatures
recognising and acting upon unstable/sub-optimal operation (e.g. icing, moisture, fouling)
controlling critical variables and outputs.

All operations are performed in accordance with procedures.

HSE
All operations to which this unit applies are subject to stringent health, safety and environment requirements, which may be imposed through State or Federal legislation, and these must not be compromised at any time. Where there is an apparent conflict between performance criteria and HSE requirements, the HSE requirements take precedence.

Assessment context and methods
Assessment for this unit of competency will be on an operating plant. The unit will be assessed in as holistic a manner as is practical and may be integrated with the assessment of other relevant units of competency. Assessment will occur over a range of situations, which will include disruptions to normal, smooth operation.

Simulation may be required to allow for timely assessment of parts of this unit of competency (e.g. parts of elements 1 and 4). Simulation should be based on the actual plant and will include walk throughs of the relevant competency components. Simulations may also include the use of case studies/scenarios and role plays.

This unit of competency requires a significant body of knowledge, which will be assessed through questioning and the use of what if scenarios both on the plant (during demonstration of normal operations and walk throughs of abnormal operations) and off the plant.

Critical aspects
Competence must be demonstrated in the ability to recognise and analyse potential situations requiring action and then in implementing appropriate corrective action. The emphasis should be on the ability to stay out of trouble rather than on recovery from a disaster.

Consistent performance should be demonstrated. In particular look to see that:
early warning signs of equipment/processes needing attention or with potential problems are recognised
the range of possible causes can be identified and analysed and the most likely cause determined
appropriate action is taken to ensure a timely return to full performance
obvious problems in related plant areas are recognised and an appropriate contribution made to their solution.

These aspects may be best assessed using a range of scenarios/case studies/what ifs as the stimulus with a walk through forming part of the response. These assessment activities should include a range of problems, including new, unusual and improbable situations, which may have been generated from the past incident history of the plant, incidents on similar plants around the world, hazard analysis activities and similar sources.

Resource implications
Assessment will require access to an operating plant over an extended period of time, or a suitable method of gathering evidence of operating ability over a range of situations. A bank of scenarios/case studies/what ifs will be required as will a bank of questions, which will be used to probe the reasoning behind the observable actions.

Other assessment advice
In all plants it may be appropriate to assess this unit concurrently with relevant teamwork and communication units. For many plants, it might be appropriate for this unit to be assessed with:
PMAOPS304A - Operate and monitor compressor systems and equipment

In a major hazard facility, it may be appropriate to assess this unit concurrently with:
PMAOHS200A Participate in workplace safety procedures.

Essential knowledge
Competence includes a comprehensive understanding of the role of the refrigeration system and its integral equipment in the overall operation of the plant. In particular it includes the ability to:
identify and describe the function of all items of the refrigeration system
describe the causes and remedies of common problems such as those selected in the range of variables.

Competence includes a comprehensive understanding of the principles of refrigeration such as:
block diagram of a refrigeration system
basic principles of refrigeration
types of industrial refrigerants and their applications
the use of 'self refrigerants' (i.e., the process fluid, such as ethylene or propylene, is also the refrigerant)
methods of controlling refrigeration systems (e.g. pressure regulation)
factors affecting performance.

It also requires a knowledge of:
principles of operation of each item of equipment (e.g. heat exchangers, compressors, condensers, vaporisers, refrigerant drains, valves)
physics of operation
brittle fracture, stress limits and the affects of thermal shock on materials of construction
vapourisation, condensation and impact on process
good operating practices
contamination issues
methods of resolving problems
HAZCHEM symbols and codes.