SAQA All qualifications and part qualifications registered on the National Qualifications Framework are public property. Thus the only payment that can be made for them is for service and reproduction. It is illegal to sell this material for profit. If the material is reproduced or quoted, the South African Qualifications Authority (SAQA) should be acknowledged as the source.
SOUTH AFRICAN QUALIFICATIONS AUTHORITY 
REGISTERED UNIT STANDARD THAT HAS PASSED THE END DATE: 

Select and specify types of refrigeration systems 
SAQA US ID UNIT STANDARD TITLE
9453  Select and specify types of 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  8 
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 
Select and specify various refrigeration systems incorporating single or multiple compressor, evaporators and/or condenser both in single and multi-stage applications and discuss typical applications. 

LEARNING ASSUMED TO BE IN PLACE AND RECOGNITION OF PRIOR LEARNING 
  • Understanding of the fundamentals of refrigeration.
  • Explain the operation of the vapour compression refrigeration cycle, and identify and explain the operation of the components and the associated controls, safety devices and defrost systems.
  • Explain function and operation of refrigeration circuits as applied to air-conditioning and refrigeration systems and select and explain the function of components, accessories and controls.
  • Analyze the refrigeration cycle as applied to refrigeration and air-conditioning systems with the aid of the pressure-enthalpy diagram and refrigerant tables.
  • Demonstrate knowledge of refrigeration systems operating on ammonia.
  • Select refrigerant piping to ensure proper plant operation. 
    		•

    UNIT STANDARD RANGE 
    Single and multi-stage compression, economized compression, compound compression, cascades systems, dry expansion, flooded feed, liquid recirculation, and secondary coolants. 

    Specific Outcomes and Assessment Criteria: 

    SPECIFIC OUTCOME 1 
    Describe the requirements for selecting and designing of various refrigeration systems. 

    ASSESSMENT CRITERIA     

    ASSESSMENT CRITERION 1 
    1. The operation of the various refrigeration systems is described using flow diagrams explaining the principle of operation. 

    ASSESSMENT CRITERION 2 
    2. The performance of the main components in the various refrigeration systems are discussed and their influence on the operation of the complete system explained. 

    ASSESSMENT CRITERION 3 
    3. The various considerations to be taken into account when selecting a refrigeration system are listed and explained. 
    ASSESSMENT CRITERION RANGE 
    Single-stage compression, economized compression, compound compression, cascade system compression, dry expansion feed, flooded feed, liquid recirculation, secondary coolants.
     

    ASSESSMENT CRITERION 4 
    4. The factors to be taken into account for selecting the type of refrigerant are discussed. 

    ASSESSMENT CRITERION 5 
    5. The factors to be taken into account when selecting the various components and accessory equipment of the refrigeration system are discussed. 
    ASSESSMENT CRITERION RANGE 
    Compressors, condensers, evaporators, receivers, sub-coolers, intercoolers, expansion tanks, suction accumulators, surge drums, refrigerant liquid pumps.
     

    ASSESSMENT CRITERION 6 
    6. The design principles for refrigerant layout piping and control are discussed. 

    SPECIFIC OUTCOME 2 
    List and explain typical applications of the various systems. 

    ASSESSMENT CRITERIA     

    ASSESSMENT CRITERION 1 
    1. Typical applications of the various refrigeration systems are discussed. 

    ASSESSMENT CRITERION 2 
    2. The advantages and limitations of the various systems are listed and discussed. 

    ASSESSMENT CRITERION 3 
    3. The various systems are compared and optimised for the particular application. 

    ASSESSMENT CRITERION 4 
    4. The system selected is the best combination of first cost, operating cost and reliability. 

    SPECIFIC OUTCOME 3 
    Interpret design requirements and select system. 

    ASSESSMENT CRITERIA     

    ASSESSMENT CRITERION 1 
    1. The various requirements to be considered when selecting a refrigeration system are listed and discussed. 

    ASSESSMENT CRITERION 2 
    2. System practices for specific refrigeration systems are discussed. 
    ASSESSMENT CRITERION RANGE 
    Piping to and from main equipment, oil separation and return.
     

    ASSESSMENT CRITERION 3 
    3. Moisture and contaminant control in refrigeration systems is explained. 

    ASSESSMENT CRITERION 4 
    4. Requirements of secondary coolants in refrigeration systems are listed and applications explained. 

    ASSESSMENT CRITERION 5 
    5. The requirements governing the selection of refrigerants for particular systems are explained. 

    SPECIFIC OUTCOME 4 
    Discuss factors to be considered when specifying a system for a particular application. 

    ASSESSMENT CRITERIA     

    ASSESSMENT CRITERION 1 
    1. The performance data for which the components of the refrigeration system have been designed, are specified to ensure unambiguous procurement of the components. 
    ASSESSMENT CRITERION RANGE 
    Capacities, room and ambient air temperatures and humidity, refrigerant, secondary coolant.
     

    ASSESSMENT CRITERION 2 
    2. The environment in which the components and total system are to operate is specified. 

    ASSESSMENT CRITERION 3 
    3. A final design report is prepared in which all design considerations and details are explained and discussed. 

    ASSESSMENT CRITERION 4 
    4. A technical specification used for tendering purposes and based on the design report is prepared. 


    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 
  • Knowledge of advantages and limitations of various refrigeration systems.
  • Interaction between main components of system and environment.
  • Importance of a correct and complete specification.
  • The effect of correct selection on owning costs. 
    		•


    Critical Cross-field Outcomes (CCFO): 

    UNIT STANDARD CCFO IDENTIFYING 
    Identify and solve problems
  • Selecting optimum refrigeration system to meet customer requirements 
    		•

    UNIT STANDARD CCFO WORKING 
    Work effectively with others
  • Working as part of a design team 
    		•

    UNIT STANDARD CCFO ORGANISING 
    Organize and manage myself and my activities responsibly and effectively
  • Obtaining the correct design and technical information for optimum design 
    		•

    UNIT STANDARD CCFO COMMUNICATING 
    Communicate effectively
  • Preparing final design report and specification 
    		•

    UNIT STANDARD CCFO SCIENCE 
    Use science and technology effectively and critically
  • Using technical information for design 
    		•

    UNIT STANDARD CCFO DEMONSTRATING 
    Demonstrate an understanding of the world as a set of related systems
  • Impact of incorrect selection of system on cost effectiveness of plant 
    		•

    UNIT STANDARD CCFO CONTRIBUTING 
    Learner and societal development
  • By learning how to select and specify refrigeration systems for particular applications 
    		•

    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.
     
    NONE 


    All qualifications and part qualifications registered on the National Qualifications Framework are public property. Thus the only payment that can be made for them is for service and reproduction. It is illegal to sell this material for profit. If the material is reproduced or quoted, the South African Qualifications Authority (SAQA) should be acknowledged as the source.