SAQA

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SOUTH AFRICAN QUALIFICATIONS AUTHORITY

REGISTERED UNIT STANDARD THAT HAS PASSED THE END DATE:

Design simplex refrigeration systems

SAQA US ID	UNIT STANDARD TITLE
9466	Design simplex refrigeration systems
ORIGINATOR
SGB Air-conditioning Refrigeration and Ventilation
PRIMARY OR DELEGATED QUALITY ASSURANCE FUNCTIONARY
-
FIELD			SUBFIELD
Field 06 - Manufacturing, Engineering and Technology			Engineering and Related Design
ABET BAND	UNIT STANDARD TYPE	PRE-2009 NQF LEVEL	NQF LEVEL	CREDITS
Undefined	Regular	Level 5	Level TBA: Pre-2009 was L5	15
REGISTRATION STATUS		REGISTRATION START DATE	REGISTRATION END DATE	SAQA DECISION NUMBER
Passed the End Date - Status was "Registered"		2001-06-13	2004-06-13	SAQA 0836/01
LAST DATE FOR ENROLMENT		LAST DATE FOR ACHIEVEMENT
2005-06-13		2008-06-13

In all of the tables in this document, both the pre-2009 NQF Level and the NQF Level is shown. In the text (purpose statements, qualification rules, etc), any references to NQF Levels are to the pre-2009 levels unless specifically stated otherwise.

This unit standard does not replace any other unit standard and is not replaced by any other unit standard.

PURPOSE OF THE UNIT STANDARD

To identify and confirm customer and system requirements.
To select a suitable simplex refrigeration system for cold and freezer rooms up to 120 m? and to select the components and controls to suit the application or according to specifications.
Prepare designs that meet these requirements and prepare design and system documentation.
Prepare power and control diagrams.

LEARNING ASSUMED TO BE IN PLACE AND RECOGNITION OF PRIOR LEARNING

Explain the function and operation of refrigeration circuits as applied to refrigeration systems and select and explain the function of components, accessories and controls.
Analyse the refrigeration cycle as applied to refrigeration systems with the aid of the pressure-enthalpy diagram and refrigerant tables.
Calculate the cooling requirements for cold and freezer rooms for short and long term storage of consumables.
Draw free hand diagrams of typical electrical control and power circuits.
Interpret electrical power and control diagrams.

UNIT STANDARD RANGE

Simplex systems for cold room and freezer rooms up to a volume of 120 m?, controlled by either a thermostat or a pressure switch.

Specific Outcomes and Assessment Criteria:

SPECIFIC OUTCOME 1

Select simplex refrigeration system.

ASSESSMENT CRITERIA

ASSESSMENT CRITERION 1

1. Customer's requirements are evaluated, quantified and confirmed.

ASSESSMENT CRITERION 2

2. Installation site is determined, inspected and evaluated.

ASSESSMENT CRITERION 3

3. Operation, implications, costs and benefits of alternative systems are considered and explained.

ASSESSMENT CRITERION 4

4. The most cost effective design is selected.

ASSESSMENT CRITERION 5

5. Design parameters required to satisfy system and customer requirements are established and explained.

SPECIFIC OUTCOME 2

Select refrigerant, system components and accessories.

ASSESSMENT CRITERIA

ASSESSMENT CRITERION 1

1. A suitable type of refrigerant is selected.

ASSESSMENT CRITERION 2

2. Main components for the system are selected and optimised.

ASSESSMENT CRITERION RANGE

Compressor, condenser (or condensing unit), evaporator and expansion device.

ASSESSMENT CRITERION 3

3. Accessories required to meet design specification are selected.

ASSESSMENT CRITERION RANGE

Pressure switches and controllers, refrigerant flow control devices, filter-driers, sight glass and valves.

ASSESSMENT CRITERION 4

4. Equipment and component capacities are calculated and their performance under part load determined.

ASSESSMENT CRITERION 5

5. Consequences of oversized or undersized components and accessories are listed and discussed.

ASSESSMENT CRITERION 6

6. The consequences of selecting an unsuitable refrigerant are listed and discussed.

SPECIFIC OUTCOME 3

Select a suitable control system and control components.

ASSESSMENT CRITERIA

ASSESSMENT CRITERION 1

1. A suitable type of control system is selected and motivated.

ASSESSMENT CRITERION RANGE

Control by thermostat or pressure switch.

ASSESSMENT CRITERION 2

2. Suitable control components are selected.

ASSESSMENT CRITERION RANGE

Thermostats, pressure switches, head pressure controls.

ASSESSMENT CRITERION 3

3. Set points for all controls are determined correctly.

ASSESSMENT CRITERION 4

4. A suitable defrost system, if required, is selected and motivated.

ASSESSMENT CRITERION 5

5. Consequences of selecting unsuitable controls are listed and discussed.

SPECIFIC OUTCOME 4

Design an electrical power and control diagram.

ASSESSMENT CRITERIA

ASSESSMENT CRITERION 1

1. All loads are determined correctly.

ASSESSMENT CRITERION 2

2. All safeties and interlocks are determined correctly.

ASSESSMENT CRITERION 3

3. The power diagram is drawn correctly according to SI standards.

ASSESSMENT CRITERION 4

4. The control diagram is drawn correctly according to SI standards.

ASSESSMENT CRITERION 5

5. Suitable methods of energising the loads are selected and explained.

ASSESSMENT CRITERION 6

6. The total electrical power requirements are determined correctly.

ASSESSMENT CRITERION 7

7. The sequence of operation of the system is explained.

ASSESSMENT CRITERION 8

8. Possible design faults are listed and their consequences explained.

SPECIFIC OUTCOME 5

Consolidate design procedures.

ASSESSMENT CRITERIA

ASSESSMENT CRITERION 1

1. Detailed designs and specifications are prepared and accepted by the customer.

ASSESSMENT CRITERION 2

2. Specifications and designs meet legislative and regulatory requirements and are consistent with industry norms.

ASSESSMENT CRITERION 3

3. Expected life of plant, operating cost and impact on the environment and safety to others are addressed in the designs.

SPECIFIC OUTCOME 6

Prepare design documentation.

ASSESSMENT CRITERIA

ASSESSMENT CRITERION 1

1. Plans for assembly, installation and commissioning are prepared in accordance with company procedures.

ASSESSMENT CRITERION 2

2. All component and system requirements are correctly specified.

ASSESSMENT CRITERION 3

3. Operating manuals and instructions for the operation and management of the system are prepared in line with company procedures.

ASSESSMENT CRITERION 4

4. The manuals and instructions are in line with industry norms and relevant legislative and regulatory requirements.

UNIT STANDARD ACCREDITATION AND MODERATION OPTIONS

Any person wishing to be assessed against this unit standard may apply to an assessment agency, assessor or provider institution accredited by the relevant ETQA, who may appoint a moderator to be present at the assessment.

The assessor must have knowledge and experience of air-conditioning or refrigeration.

UNIT STANDARD ESSENTIAL EMBEDDED KNOWLEDGE

Design procedures and methods, design documentation.

Regulatory and statutory requirements governing design.

Using engineering and scientific principles in design of systems.

Matching components, accessories and controls of the system

Designing electrical power and control diagrams

Critical Cross-field Outcomes (CCFO):

UNIT STANDARD CCFO IDENTIFYING

Identify and solve problems

Identifying customer, site and system requirements for optimum design

UNIT STANDARD CCFO ORGANISING

Organise and manage myself and my activities responsibly and effectively

Identifying design parameters to carry out design and selecting required components, accessories and controls

UNIT STANDARD CCFO COMMUNICATING

Communicate effectively

Discussing design proposals with customer and presenting written design report and specifications

UNIT STANDARD CCFO SCIENCE

Use science and technology effectively and critically

Using sound engineering principles in design of system

UNIT STANDARD CCFO DEMONSTRATING

Demonstrate an understanding of the world as a set of related systems

Selection of materials to be environmentally acceptable

Impact of sub-standard design on operation and costs of plant

UNIT STANDARD CCFO CONTRIBUTING

Learner and societal development

By learning sound engineering design principles

UNIT STANDARD NOTES

Specific requirements are contained in one or more of the following documents:

Statutory and regulatory requirements.

Manufacturer`s instructions and technical information regarding operation of component and equipment specified.

Company design procedures and guidelines.

Industry norms regarding design and design documentation.

QUALIFICATIONS UTILISING THIS UNIT STANDARD:

	ID	QUALIFICATION TITLE	PRE-2009 NQF LEVEL	NQF LEVEL	STATUS	END DATE	PRIMARY OR DELEGATED QA FUNCTIONARY
Core	20722	National Diploma: Air Conditioning, Refrigeration and Ventilation	Level 5	Level TBA: Pre-2009 was L5	Passed the End Date - Status was "Registered"	2004-06-13	MERSETA

PROVIDERS CURRENTLY ACCREDITED TO OFFER THIS UNIT STANDARD:

This information shows the current accreditations (i.e. those not past their accreditation end dates), and is the most complete record available to SAQA as of today. Some Primary or Delegated Quality Assurance Functionaries have a lag in their recording systems for provider accreditation, in turn leading to a lag in notifying SAQA of all the providers that they have accredited to offer qualifications and unit standards, as well as any extensions to accreditation end dates. The relevant Primary or Delegated Quality Assurance Functionary should be notified if a record appears to be missing from here.

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