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:

Design ammonia refrigeration systems as described in 8) and including:

A

Understanding required operating functions and parameters from the design specification

B

Developing the design within the safety, regulatory and functional requirements and budget limitations

C

Documenting and presenting design effectively

D

Successfully negotiating design alteration requests

E

Obtaining approval for final design

F

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 designing ammonia refrigeration systems.

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..

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 designing single-stage and/or multi-stage ammonia refrigerating systems.

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

KS01-EJ181A

Ammonia refrigeration system design

Evidence shall show an understanding of Ammonia refrigeration systems, components and piping design requirements, applying safe working practices and relevant Standards, Codes and Regulations to an extent indicated by the following aspects:

T1 Technical Standards, Codes and Regulations

Environmental and safety considerations in the use and disposal of ammonia refrigerant

Toxicity of ammonia, the effects on human health and the legislative limitations imposed on ammonia refrigerant as a result

Flammability of ammonia, concentration, LEL

Environmental effects

Safe disposal

MSDS samples

Registration requirements for transport and on-site use

Relationship between ammonia system refrigerant charge and Dangerous Goods Storage regulations

Engine ventilation requirements and determination of ventilation rates

Scrubbers for elimination of the harmful effects of ammonia

T2 Ammonia refrigeration system design requirements

Applications of refrigerant ammonia (NH3) in industrial refrigeration

Introduction to industrial ammonia refrigeration applications and systems

Applications in Industrial Refrigeration: Cool and cold storage, food processing, beverage manufacturing plants, fertilizer plants, second compression stage of CO2 systems

Application in environment control and air conditioning: Large scale reticulated water/secondary refrigerant systems

Advantages and disadvantages of ammonia refrigerant compared with other natural and synthetic refrigerants

Properties, application and limitations of ammonia refrigerant

General classification of ammonia refrigerant according to AS 1677 Refrigerating Systems

Common contaminants in ammonia refrigeration systems, water, oil, non-condensable and the effects of same on cycle efficiency and system wear

Refrigeration machine oils soluble in ammonia, oil type, applications, reactions with water

Thermal and transport properties of ammonia in comparison with other natural and synthetic refrigerants including the behaviour in a vapour compression cycle

Application concepts and principles

Single stage vapour compression cycles with dry expansion refrigerant feed

Single and dual stage vapour compression cycles with liquid overfeed

Single stage vapour compression cycles with screw compressors and liquid overfeed

Cascade NH3/CO2 systems with dry expansion and liquid overfeed

Single and dual stage vapour compression cycles with gravity flooded refrigerant feed

Single and dual stage vapour compression cycles with NH3 used as a volatile secondary refrigerant

Dual stage vapour compression cycles with multiple (>2) saturation temperature levels

Automatic defrost principles including off-cycle air defrost, ambient air defrost, hot gas defrost, electric defrost and water defrost

Selection and sizing of ammonia pumps for liquid overfeed systems

Selection and sizing of high pressure and low pressure vessels

Refrigerant pipe sizing using Ammonia refrigerant

Selection of suitable refrigerant oil

T3 Ammonia refrigeration system components and piping

Corrosion and Material selection

Materials compatibility table

Thermal and other properties of materials in use

Pipe material and jointing methods/materials

Compressors

Pumps, impellers and seals

Isolation and control valves

Heat exchangers

Pipe and insulation materials, pipe stresses and pipe suspension methods

Mild steel pipe

Stainless steel pipe

Sharpy tested pipe

Post-installation insulation (in situ foaming, formed insulation, closed cell flexible insulation

Pre-insulated pipe material

Vapour barrier – importance and maintenance

Heat exchangers

Finned air coolers or evaporators - induced draught, forced draught, stainless steel/aluminium, mild steel galvanized, all aluminium, stainless steel/AlMg3, all stainless steel; description of what materials are used where and for what reason; various refrigerant feed methods including advantages/disadvantages i.e. top feed, bottom feed, vertical up flow/down flow of air; fin spacing, fin thickness; impact of geometry on fluid pressure drops

Condensers – evaporative, air cooled, air cooled adiabatically assisted, water cooled shell and tube, water cooled plate/plate, water cooled plate and shell, cascade shell and tube, cascade plate/plate, cascade plate and shell; material selection for condensers, importance of discharge temperature for condenser design

Cooling towers

Intercoolers and economizers of the closed type, sizing of liquid subcooling coils and tube bundles

Liquid coolers or evaporators – plate/plate, plate/shell, shell and tube; material selections, refrigerant feed methods, oil management

Screw compressor oil coolers – plate/plate type, shell and tube type, water cooled, refrigerant cooled, surface enhancement options

Heat recovery – shell and tube de-superheaters, plate/plate de-superheaters, heat recovery condensers of various types

System control and monitoring

Compressor capacity control – pressure and temperature signals

Room temperature and humidity control – understanding the principle of cooling and re-heating air streams to control absolute moisture contents

Control of condensers – optimization of overall plant C.O.P.

Floating condensing pressures

Control of fluid temperatures within the system – oil, secondary refrigerants, subcooling

Control of flows – thermostatic expansion valves, low pressure floats, high pressure floats, motorized valves, electronic expansion valves, hand regulating valves, oil return systems between compressor oil separators and compressors

Pressure controllers - evaporating pressure controllers, thermostatic controllers, hot gas bypass valves, crankcase pressure regulators, overflow valves, NH3 pump pressure control, flow controllers, defrost pressure controllers

Defrost control

PLC control systems

SCADA systems

Water treatment and desiccant dehumidifiers

Condenser water treatment – purpose and legislative requirement

Treatment of secondary refrigerant loops including monitoring

Desiccant dehumidifiers and their role in infiltration minimization, defrost control and energy savings

Equipment Selection

Use computer software and manufacturers data to select major components of an Ammonia refrigeration plant

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 designing ammonia refrigeration systems in any of the following:

In relation to at least two of the following types of (2 single-stage or 2 multi-stage or 1 single-stage and 1 multi-stage) ammonia refrigeration systems encompassing major components (i.e. condenser, compressors, evaporator, and flash chamber/flash intercooler), associated components and controls and on at least two occasions:

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.