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Evidence Guide: UEENEEJ185A - Repair and service carbon dioxide refrigeration systems

Student: __________________________________________________

Signature: _________________________________________________

Tips for gathering evidence to demonstrate your skills

The important thing to remember when gathering evidence is that the more evidence the better - that is, the more evidence you gather to demonstrate your skills, the more confident an assessor can be that you have learned the skills not just at one point in time, but are continuing to apply and develop those skills (as opposed to just learning for the test!). Furthermore, one piece of evidence that you collect will not usualy demonstrate all the required criteria for a unit of competency, whereas multiple overlapping pieces of evidence will usually do the trick!

From the Wiki University

 

UEENEEJ185A - Repair and service carbon dioxide refrigeration systems

What evidence can you provide to prove your understanding of each of the following citeria?

Prepare to service and repair carbon dioxide refrigeration systems

  1. OHS procedures for a given work area are identified, obtained and understood through established routines and procedures
  2. Established OHS risk control measures and procedures are followed in preparation for the work.
  3. Safety hazards which have not previously been identified are reported and advice on risk control measures is sought from the work supervisor.
  4. The nature of work is obtained from documentation or from work supervisor to establish the scope of work to be undertaken.
  5. Advice is sought from the work supervisor to ensure the work is coordinated effectively with others.
  6. Sources of materials that may be required for the work are accessed in accordance with established routines and procedures.
  7. Tools, equipment and testing devices needed to carry out the work are obtained and checked for correct operation and safety
OHS procedures for a given work area are identified, obtained and understood through established routines and procedures

Completed
Date:

Teacher:		 Evidence:

 

 

 

 

 

 

 

Established OHS risk control measures and procedures are followed in preparation for the work.

Completed
Date:

Teacher:		 Evidence:

 

 

 

 

 

 

 

Safety hazards which have not previously been identified are reported and advice on risk control measures is sought from the work supervisor.

Completed
Date:

Teacher:		 Evidence:

 

 

 

 

 

 

 

The nature of work is obtained from documentation or from work supervisor to establish the scope of work to be undertaken.

Completed
Date:

Teacher:		 Evidence:

 

 

 

 

 

 

 

Advice is sought from the work supervisor to ensure the work is coordinated effectively with others.

Completed
Date:

Teacher:		 Evidence:

 

 

 

 

 

 

 

Sources of materials that may be required for the work are accessed in accordance with established routines and procedures.

Completed
Date:

Teacher:		 Evidence:

 

 

 

 

 

 

 

Tools, equipment and testing devices needed to carry out the work are obtained and checked for correct operation and safety

Completed
Date:

Teacher:		 Evidence:

 

 

 

 

 

 

 

Service and repair carbon dioxide refrigeration systems.

  1. Established OHS risk control measures and procedures for carrying out the work are followed.
  2. Measuring system operating parameters is conducted in strict accordance with OHS requirements and established safety procedures
  3. Checks are carried out to ensure the system or component parts are isolated, when necessary in strict accordance OHS requirements and procedures.
  4. Refrigerant is removed from a system safely in accordance with regulatory requirements and industry practices.
  5. Precautions are taken to prevent damage to components while pressure testing the system
  6. Pressure testing is conducted at a pressure compatible with carbon dioxide and in accordance with standards
  7. Leaks are located and rectified using testing methods appropriate to the system and in accordance with industry practices
  8. System is evacuated to the required level and cleaned of all moisture and other contaminants in accordance with industry practices
  9. System is charged safely with refrigerant grade carbon dioxide and compatible lubricants in accordance with industry practices
  10. Established procedures are used to determine actual and specified range of operating conditions from measured and calculated values as they apply to sub critical carbon dioxide vapour compression and liquid recirculation/cascade systems.
  11. Established methods for dealing with unexpected situations are discussed with appropriate person or persons and documented.
  12. Unexpected situations are dealt with safely and with the approval of an authorised person.
  13. Operating conditions are determined without damage to apparatus, circuits, the surrounding environment or services and using sustainable energy practices.
Established OHS risk control measures and procedures for carrying out the work are followed.

Completed
Date:

Teacher:		 Evidence:

 

 

 

 

 

 

 

Measuring system operating parameters is conducted in strict accordance with OHS requirements and established safety procedures

Completed
Date:

Teacher:		 Evidence:

 

 

 

 

 

 

 

Checks are carried out to ensure the system or component parts are isolated, when necessary in strict accordance OHS requirements and procedures.

Completed
Date:

Teacher:		 Evidence:

 

 

 

 

 

 

 

Refrigerant is removed from a system safely in accordance with regulatory requirements and industry practices.

Completed
Date:

Teacher:		 Evidence:

 

 

 

 

 

 

 

Precautions are taken to prevent damage to components while pressure testing the system

Completed
Date:

Teacher:		 Evidence:

 

 

 

 

 

 

 

Pressure testing is conducted at a pressure compatible with carbon dioxide and in accordance with standards

Completed
Date:

Teacher:		 Evidence:

 

 

 

 

 

 

 

Leaks are located and rectified using testing methods appropriate to the system and in accordance with industry practices

Completed
Date:

Teacher:		 Evidence:

 

 

 

 

 

 

 

System is evacuated to the required level and cleaned of all moisture and other contaminants in accordance with industry practices

Completed
Date:

Teacher:		 Evidence:

 

 

 

 

 

 

 

System is charged safely with refrigerant grade carbon dioxide and compatible lubricants in accordance with industry practices

Completed
Date:

Teacher:		 Evidence:

 

 

 

 

 

 

 

Established procedures are used to determine actual and specified range of operating conditions from measured and calculated values as they apply to sub critical carbon dioxide vapour compression and liquid recirculation/cascade systems.

Completed
Date:

Teacher:		 Evidence:

 

 

 

 

 

 

 

Established methods for dealing with unexpected situations are discussed with appropriate person or persons and documented.

Completed
Date:

Teacher:		 Evidence:

 

 

 

 

 

 

 

Unexpected situations are dealt with safely and with the approval of an authorised person.

Completed
Date:

Teacher:		 Evidence:

 

 

 

 

 

 

 

Operating conditions are determined without damage to apparatus, circuits, the surrounding environment or services and using sustainable energy practices.

Completed
Date:

Teacher:		 Evidence:

 

 

 

 

 

 

 

Complete work and report on servicing and repairing sub - critical carbon dioxide refrigeration systems.

  1. OHS work completion risk control measures and procedures are followed.
  2. Work site is cleaned and made safe in accordance with established procedures.
  3. Contaminated refrigerant and lubricant is dealt with in accordance with legislative/regulatory requirements
  4. Operation conditions are documented, including identification of any parameter that is not within the specified range for the system.
  5. Work supervisor is notified of the completion of the work in accordance with established procedures.
OHS work completion risk control measures and procedures are followed.

Completed
Date:

Teacher:		 Evidence:

 

 

 

 

 

 

 

Work site is cleaned and made safe in accordance with established procedures.

Completed
Date:

Teacher:		 Evidence:

 

 

 

 

 

 

 

Contaminated refrigerant and lubricant is dealt with in accordance with legislative/regulatory requirements

Completed
Date:

Teacher:		 Evidence:

 

 

 

 

 

 

 

Operation conditions are documented, including identification of any parameter that is not within the specified range for the system.

Completed
Date:

Teacher:		 Evidence:

 

 

 

 

 

 

 

Work supervisor is notified of the completion of the work in accordance with established procedures.

Completed
Date:

Teacher:		 Evidence:

 

 

 

 

 

 

 

Assessed

Teacher: ___________________________________ Date: _________

Signature: ________________________________________________

Comments:

 

 

 

 

 

 

 

 

Instructions to Assessors

Evidence Guide

9) The evidence guide provides advice on assessment and must be read in conjunction with the Performance Criteria, Required Skills and Knowledge, the Range Statement and the Assessment Guidelines for this Training Package. .

The Evidence Guide forms an integral part of this unit. It must be used in conjunction with all parts of this unit and performed in accordance with the Assessment Guidelines of this Training Package.

Overview of Assessment

9.1)

Longitudinal competency development approaches to assessment, such as Profiling, require data to be reliably gathered in a form that can be consistently interpreted over time. This approach is best utilised in Apprenticeship programs and reduces assessment intervention. It is the industry-preferred model for apprenticeships. However, where summative (or final) assessment is used it is to include the application of the competency in the normal work environment or, at a minimum, the application of the competency in a realistically simulated work environment. In some circumstances, assessment in part or full can occur outside the workplace. However, it must be in accordance with industry and regulatory policy.

Methods chosen for a particular assessment will be influenced by various factors. These include the extent of the assessment, the most effective locations for the assessment activities to take place, access to physical resources, additional safety measures that may be required and the critical nature of the competencies being assessed.

The critical safety issues inherent in working with electricity, electrical equipment, gas or any other hazardous substance/material present a challenge for those determining competence. Sources of evidence need to be 'rich' in nature to minimise error in judgment.

Activities associated with normal everyday work have a bearing on the decision as to how much and how detailed the data gathered will contribute to its 'richness'. Some skills are more critical to safety and operational requirements while the same skills may be more or less frequently practised. These points are raised for the assessors to consider when choosing an assessment method and developing assessment instruments. Sample assessment instruments are included for Assessors in the Assessment Guidelines of this Training Package.

Critical aspects of evidence required to demonstrate competency in this unit

9.2)

Before the critical aspects of evidence are considered all prerequisites must be met.

Evidence for competence in this unit must be considered holistically. Each element and associated performance criteria must be demonstrated on at least two occasions in accordance with the 'Assessment Guidelines - UEE07 '. Evidence must also comprise:

A representative body of work performance demonstrated within the timeframes typically expected of the discipline, work function and industrial environment. In particular this must incorporate evidence that shows a candidate is able to:

Implement Occupational Health and Safety workplace procedures and practices including the use of risk control measures as specified in the performance criteria and range statement

Apply sustainable energy principles and practices as specified in the performance criteria and range statement

Demonstrate an understanding of the essential knowledge and associated skills as described in this unit. It may be required by some jurisdictions that RTOs provide a percentile graded result for the purpose of regulatory or licensing requirements.

Demonstrate an appropriate level of skills enabling employment

Conduct work observing the relevant Anti Discrimination legislation, regulations, polices and workplace procedures

Demonstrated consistent performance across a representative range of contexts from the prescribed items below:

Pressure testing, charging/discharging refrigerant/lubricants and determining the operating conditions of Carbon Dioxide vapour compression and volatile secondary ( liquid recirculation) system as described in 8) and including:

A

Selecting and using appropriate measuring devices correctly

B

Recording measurements

C

Using calculation methods accurately

D

Discharging / charging refrigerant / lubricants and pressure testing the system without damage to components

E

Locating and rectifying leaks

F

Decontaminating and evacuating the system

G

Identifying the conditions of the refrigerant (R744) at various locations in the vapour compression and volatile secondary (liquid recirculation) system

H

Documenting operating conditions correctly

I

Dealing with unplanned events by drawing on essential knowledge and skills to provide appropriate solutions incorporated in a holistic assessment with the above listed items

Context of and specific resources for assessment

9.3)

This unit should be assessed as it relates to normal work practice using procedures, information and resources typical of a workplace. This should include:

OHS policy and work procedures and instructions.

Suitable work environment, facilities, equipment and materials to undertake actual work as prescribed by this unit.

These should be part of the formal learning/assessment environment.

Note:

Where simulation is considered a suitable strategy for assessment, conditions must be authentic and as far as possible reproduce and replicate the workplace and be consistent with the approved industry simulation policy.

The resources used for assessment should reflect current industry practices in relation to servicing and repairing as well as determining the operating conditions of Carbon Dioxide vapour compression and liquid recirculation/cascade system.

Method of assessment

9.4)

This unit shall be assessed by methods given in Volume 1, Part 3 'Assessment Guidelines'.

Note:
Competent performance with inherent safe working practices is expected in the Industry to which this unit applies. This requires assessment in a structured environment which is intended primarily for learning/assessment and incorporates all necessary equipment and facilities for learners to develop and demonstrate the essential knowledge and skills described in this unit.

Concurrent assessment and relationship with other units

9.5)

There are no concurrent assessment recommendations for this unit.

The critical aspects of occupational health and safety covered in unit UEENEEE001B and other discipline specific occupational health and safety units shall be incorporated in relation to this unit..

Required Skills and Knowledge

7) This describes the essential skills and knowledge and their level, required for this unit.

Evidence must show that knowledge has been acquired of safe working practices and determining the operating conditions of both sub - critical vapour compression and liquid recirculating carbon dioxide refrigerating systems.

All knowledge and skills detailed in this unit should be contextualised to current industry practices and technologies.

KS01-EJ185A

Servicing and repair techniques for carbon dioxide refrigeration Systems

Evidence shall show an understanding of carbon dioxide refrigeration systems, operation, components, service and repair techniques, applying safe working practices and relevant Standards, Codes and Regulations to an extent indicated by the following aspects:

T1 Carbon Dioxide Refrigeration Systems

Introduction to Carbon Dioxide refrigeration System

Benefits of using Carbon Dioxide as a Refrigerant

Thermophysical Properties

Introduction to Liquid recirculation /Cascade system employing Carbon Dioxide refrigerant at Sub-Critical condition.

Systems and Major components

Basic operation

Typical applications

T2 Operating conditions of carbon dioxide Refrigeration Systems

CO2 Refrigeration Compressors and lubricants

Types, construction and their applications (reciprocating, screw, )

Types of compatible compressor oil (POE), (PAO)

Safe handling of lubricants for CO2 applications (MSDS - POE's, PAO)

System components, construction and operation

CO2 Low temperature evaporators design features

Medium Temperature Liquid re-circulation evaporators

Hand expansion valves (medium temp.)

Electronic expansion valves (low temp)

Cryogenic pressure relief devices

Plate heat exchangers

Liquid –Suction heat exchangers

Liquid CO2 Refrigerant Pumps

"Q" Min and "Q" Max valves

Interconnecting piping

Refrigerant receiver

Isolation valves

Applicable Standards and Codes

Hazards associated with Carbon Dioxide (MSDS)

AS/NZS 1677

AS/NZS 1571

IIAR Bulletins

ANSI/ASHRAE Standards

IOR Safety code for Refrigerating Systems utilising Carbon Dioxide

T3 Servicing and repair techniques for carbon dioxide refrigeration systems

Service Gauges

Appropriate Type

Care and Maintenance of Gauges and hoses

Service procedures

Charging CO2 into a system in both vapour and liquid form

Discharging CO2 from a system safely

Pressure testing

System and component isolation

Leak detection methods for CO2

Cylinder Regulators CO2

All currently available regulators provide vapour feed only

Pressure readings (bottle and line)

Refrigerant Cylinders CO2

Refrigerant conditions

Hazards and related safe working practices (dangerous system pressures)

Pressure to temperature conversion (Saturated P/T is only between 430 kPa and 4399kPa)

System standing pressure as a result of power loss.

Moisture problems with CO2 systems

Range Statement

8) This relates to the unit as a whole providing the range of contexts and conditions to which the performance criteria apply. It allows for different work environments and situations that will affect performance.

This unit must be demonstrated in relation to determining operating conditions using measurement and basic calculation methods of carbon dioxide vapour compression and volatile secondary (liquid recirculation) system. These conditions include 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 of carbon dioxide (R744). Further, this unit must be demonstrated in relation to charging and discharging a carbon dioxide (R744) system with refrigerant and lubricant in a safe and environmentally responsible manner. This excludes self contained systems.

Generic terms used throughout this Vocational Standard shall be regarded as part of the Range Statement in which competency is demonstrated. The definition of these and other terms that apply are given in Volume 2, Part 2.1.