This unit involves the skills and knowledge required to design ammonia refrigerated systems.

It includes designing ammonia refrigerated systems based on a design brief and customer requirements, applying relevant industry standards, selecting components and documenting system design.

The skills and knowledge described in this unit may, in some jurisdictions, require a licence or permit to practice in the workplace subject to regulations for undertaking refrigeration and air conditioning work. Practice in the workplace and during training is also subject to work health and safety (WHS)/occupational health and safety (OHS) regulations.

No other licensing, legislative or certification requirements apply to this unit at the time of publication.

ELEMENTS

PERFORMANCE CRITERIA

Elements describe the essential outcomes.

Performance criteria describe the performance needed to demonstrate achievement of the element.

1

Prepare to design ammonia refrigeration systems

1.1

WHS/OHS requirements and workplace procedures for a given work area are identified, obtained and applied

1.2

Scope of the refrigeration system is determined from design specifications and/or in consultation with relevant person/s

1.3

Safety systems are identified, obtained and applied in accordance with relevant industry standard

1.4

Work supervisor and/or customer/s are consulted to determine functions and parameters of the system required in accordance with design specifications and workplace documentation

1.5

Design development work is planned in accordance with workplace procedures for timelines in consultation with others involved

2

Design ammonia refrigeration systems

2.1

WHS/OHS risk control measures and workplace procedures for carrying out the work are followed

2.2

Relevant ammonia refrigeration system analysis, components and piping are applied to developing the system design in accordance with workplace procedures and relevant industry standards

2.3

Safety, functionality and budgetary considerations are incorporated in the design specifications

2.4

Equipment required is selected in accordance with the design specifications and workplace procedures

2.5

Location of components is documented in accordance with workplace procedures and operation of system functions

2.6

System design draft is checked for compliance with the design brief and regulatory requirements

2.7

System design is documented for submission to relevant person/s for approval

2.8

Unplanned events are dealt with in accordance with problem-solving techniques and workplace procedures

3

Obtain approval for engineering computer applications design

3.1

System design is presented to customer and/or relevant person/s in accordance with workplace procedures

3.2

Requests for alterations to the design are negotiated with relevant person/s in accordance with workplace procedures

3.3

Final design is documented and approval obtained from relevant person/s in accordance with workplace procedures

3.4

Quality of work is monitored in accordance with workplace procedures and relevant industry standards

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 one occasion and include:

understanding required operating functions and parameters from the design specification

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

documenting and presenting design effectively

negotiating design alteration requests successfully

obtaining approval for final design

dealing with unplanned events

applying relevant work health and safety (WHS)/occupational health and safety (WHS/OHS) requirements, including using risk control measures

designing ammonia refrigeration systems

preparing to design ammonia refrigeration systems.

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:

ammonia refrigeration system design, components and piping design requirements, safe working practices and relevant standards, codes and regulations, including:

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 and lower explosive limit (LEL)

environmental effects

safe disposal

safety data sheets (SDS)/material safety data sheets (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

ammonia refrigeration system design requirements:

applications of ammonia refrigerant (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 and 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/NZS 1677 Refrigerating systems SAA refrigeration code 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 and 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 ammonia/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 ammonia 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

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 and 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 and 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, and importance of discharge temperature for condenser design

cooling towers

intercoolers and economisers of the closed type, sizing of liquid sub-cooling coils and tube bundles

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

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

heat recovery – shell and tube de-superheaters, plate/plate de-superheaters and 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 – optimisation of overall plant C.O.P

floating condensing pressures

control of fluid temperatures within the system – oil, secondary refrigerants and sub-cooling

control of flows – thermostatic expansion valves, low pressure floats, high pressure floats, motorised valves, electronic expansion valves, hand regulating valves, and 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, ammonia pump pressure control, flow controllers and defrost pressure controllers

defrost control

programmable logic controller (PLC) control systems

supervisory control and data acquisition (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 minimisation, defrost control and energy savings

equipment selection:

use computer software and manufacturers’ data to select major components of an ammonia refrigeration plant

problem-solving techniques

relevant job safety assessments or risk mitigation processes

relevant manufacturer specifications

relevant WHS/OHS legislated requirements

relevant workplace budget, quality, policies and procedures

relevant workplace documentation.

Assessors must hold credentials specified within the Standards for Registered Training Organisations current at the time of assessment.

Assessment must satisfy the Principles of Assessment and Rules of Evidence and all regulatory requirements included within the Standards for Registered Training Organisations current at the time of assessment.

Assessment must occur in suitable workplace operational situations where it is appropriate to do so; where this is not appropriate, assessment must occur in simulated suitable workplace operational situations that replicate workplace conditions.

Assessment processes and techniques must be appropriate to the language, literacy and numeracy requirements of the work being performed and the needs of the candidate.

Resources for assessment must include access to:

a range of relevant exercises, case studies and/or simulations

relevant and appropriate materials, tools, facilities and equipment currently used in industry

applicable documentation, including workplace procedures, equipment specifications, regulations, codes of practice and operation manuals.

Foundation skills essential to performance are explicit in the performance criteria of this unit of competency.

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.

Designing ammonia refrigeration systems must include at least two different systems of the following:

two single-stage, or

two multi-stage, or

one single-stage and one multi-stage

Designing ammonia refrigeration systems must include at least the following:

one major component, including:

condenser

compressors

evaporator

flash chamber/flash intercooler

associated components and controls

Electrotechnology

Refrigeration and air-conditioning