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SOUTH AFRICAN QUALIFICATIONS AUTHORITY 
REGISTERED UNIT STANDARD: 

Explain function and operation of refrigeration circuits as applied to air-conditioning or refrigeration systems and select and explain the function of components, accessories and controls 
SAQA US ID UNIT STANDARD TITLE
116418  Explain function and operation of refrigeration circuits as applied to air-conditioning or refrigeration systems and select and explain the function of components, accessories and controls 
ORIGINATOR
SGB Air-conditioning Refrigeration and Ventilation 
PRIMARY OR DELEGATED QUALITY ASSURANCE FUNCTIONARY
-  
FIELD SUBFIELD
Field 06 - Manufacturing, Engineering and Technology Manufacturing and Assembly 
ABET BAND UNIT STANDARD TYPE PRE-2009 NQF LEVEL NQF LEVEL CREDITS
Undefined  Regular  Level 4  NQF Level 04 
REGISTRATION STATUS REGISTRATION START DATE REGISTRATION END DATE SAQA DECISION NUMBER
Reregistered  2018-07-01  2023-06-30  SAQA 06120/18 
LAST DATE FOR ENROLMENT LAST DATE FOR ACHIEVEMENT
2024-06-30   2027-06-30  

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 replaces: 
US ID Unit Standard Title Pre-2009 NQF Level NQF Level Credits Replacement Status
9520  Explain function and operation of refrigeration circuits as applied to air-conditioning or refrigeration systems and select and explain the function of components, accessories and controls  Level 4  NQF Level 04  Complete 

PURPOSE OF THE UNIT STANDARD 
Explain the processes taking place in the components and accessories of a refrigeration plant in order to select the correct components and accessories. 

LEARNING ASSUMED TO BE IN PLACE AND RECOGNITION OF PRIOR LEARNING 
Explain the operation of vapour compression refrigeration systems and identify refrigeration plant components and accessories. 

UNIT STANDARD RANGE 
Air-cooled, water-cooled and evaporatively cooled DX and flooded systems as applied to air-conditioning or refrigeration systems. Direct and pilot operated controls, including crankcase pressure regulators, evaporator pressure regulators and condenser pressure control systems. Capacity control systems. Discharge by-pass valves, pressure relief valves, rupture discs, Electronic Expansion Valves. High side and low side float valves, poppet valves and orifices. 

Specific Outcomes and Assessment Criteria: 

SPECIFIC OUTCOME 1 
Explain the function and operation of various types of refrigeration systems. 
OUTCOME RANGE 
Direct expansion with capillary tube or with thermostatic expansion valve, flooded systems with high side float, flooded systems with low side float, liquid overfeed systems, reverse cycle systems. Systems with single and multiple compressors, evaporators and condensers 

ASSESSMENT CRITERIA
 

ASSESSMENT CRITERION 1 
The various refrigeration systems are listed and typical applications stated. 
ASSESSMENT CRITERION RANGE 
Air-cooled, water cooled and evaporatively cooled direct expansion, flooded, and overfeed systems.
 

ASSESSMENT CRITERION 2 
A schematic diagram of the various systems is sketched. 

ASSESSMENT CRITERION 3 
The various systems are compared and their advantages and limitations given. 

ASSESSMENT CRITERION 4 
The methods of oil return and the components required for this are discussed. 

SPECIFIC OUTCOME 2 
Explain the function and principles of operation of various refrigeration system components and accessories. 
OUTCOME RANGE 
Compressors, condensers, evaporators, metering devices, cooling towers, fans, pumps, receivers, accumulators, vibration eliminators, crankcase heaters, sight glasses, moisture indicators, service valves, shut-off valves, safety valves, fusible plugs, charging valves, filter driers, strainers, mufflers, suction-liquid line heat exchangers, oil separators. 

ASSESSMENT CRITERIA
 

ASSESSMENT CRITERION 1 
The principles of operation of components and accessories as well as the internal and external factors influencing the operation are described. 

ASSESSMENT CRITERION 2 
The purpose of installing components and accessories are listed and discussed. 

ASSESSMENT CRITERION 3 
System components and accessories are listed and identified on an actual plant. 

ASSESSMENT CRITERION 4 
Advantages and limitations of components and accessories are discussed. 

ASSESSMENT CRITERION 5 
The checks to be carried out before putting equipment into operation are explained. 

ASSESSMENT CRITERION 6 
The relevant maintenance requirements for the various system components and accessories are discussed. 

ASSESSMENT CRITERION 7 
The common faults experienced with system components and accessories are listed. 

ASSESSMENT CRITERION 8 
The factors to be considered when selecting system components and accessories are listed and discussed. 

ASSESSMENT CRITERION 9 
Components and accessories at specific given operating conditions are selected from catalogues and tables. 

ASSESSMENT CRITERION 10 
Different makes and types of components and accessories are compared and contrasted. 

ASSESSMENT CRITERION 11 
Performance graphs of components are compiled from given data to establish performance across entire load spectrum. 

SPECIFIC OUTCOME 3 
Explain the function and operation of various refrigeration system controls. 
OUTCOME RANGE 
Pressure, temperature and flow controls. 

ASSESSMENT CRITERIA
 

ASSESSMENT CRITERION 1 
The operation of various types of control are listed and identified. 

ASSESSMENT CRITERION 2 
The operation is described, compared and contrasted for the various types of control methods used in refrigeration systems. 

ASSESSMENT CRITERION 3 
The purpose for using and the position in the system of the direct and pilot operated refrigerant control devices is stated and identified. 
ASSESSMENT CRITERION RANGE 
Evaporator pressure regulators, crankcase pressure regulators, condenser pressure regulators, discharge by-pass valves, reversing valves.
 

ASSESSMENT CRITERION 4 
The purpose and position of refrigerant relief devices are stated and identified. 
ASSESSMENT CRITERION RANGE 
Fusible plugs, pressure relief valves, and rupture discs.
 

ASSESSMENT CRITERION 5 
The factors to be considered when installing control devices and methods are explained. 

ASSESSMENT CRITERION 6 
Metering and control devices are selected from catalogues and tables given operating parameters. 
ASSESSMENT CRITERION RANGE 
Expansion valves, solenoid valves, distributors, check valves, evaporator pressure regulators and crankcase pressure regulators. Determination of pressure difference across thermostatic expansion valves, high side and low side float valves.
 

ASSESSMENT CRITERION 7 
The common faults that can occur with refrigeration systems controls are listed and discussed. 

ASSESSMENT CRITERION 8 
The consequences of selecting over or undersized controls are listed and explained. 

SPECIFIC OUTCOME 4 
Prepare for selecting components and accessories. 

ASSESSMENT CRITERIA
 

ASSESSMENT CRITERION 1 
All the correct information to select the accessory or component is obtained. 

ASSESSMENT CRITERION 2 
All units / symbols for the information are checked for correctness. 

ASSESSMENT CRITERION 3 
All selection criteria are corrected for site conditions. 

ASSESSMENT CRITERION 4 
The information is checked against norms and the selection criteria for other components or accessories for the same system. 

ASSESSMENT CRITERION 5 
Any discrepancies are investigated. 

ASSESSMENT CRITERION 6 
Specifications or special requirements related to make and model numbers are checked. 

ASSESSMENT CRITERION 7 
The correct catalogues are used. 

SPECIFIC OUTCOME 5 
Select components and accessories. 

ASSESSMENT CRITERIA
 

ASSESSMENT CRITERION 1 
All selection criteria are correctly converted, if required. 

ASSESSMENT CRITERION 2 
All capacities or operating parameters are corrected according to the instructions in the catalogues. 

ASSESSMENT CRITERION 3 
The components or accessories are selected at maximum efficiency. 

ASSESSMENT CRITERION 4 
The consequences of selecting components and/or accessories that are too big or too small or differ from the specifications are explained. 

ASSESSMENT CRITERION 5 
All selection criteria are recorded in the correct SI units. 

SPECIFIC OUTCOME 6 
Record results of selection of components and accessories. 

ASSESSMENT CRITERIA
 

ASSESSMENT CRITERION 1 
The correct model number and reference number is recorded. 

ASSESSMENT CRITERION 2 
The operating parameters are recorded in the correct SI units. 

ASSESSMENT CRITERION 3 
The correct order numbers are recorded. 

ASSESSMENT CRITERION 4 
Problems in selecting the components or accessories are recorded and explained. 


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 
Names and functions of refrigeration plant components, accessories and controls.
Application and use of conversion factors and manufacturer's catalogues
Consequences of selecting the incorrect components or accessories or mismatching these
Theory of refrigeration as applied to air-conditioning or refrigeration systems. 

UNIT STANDARD DEVELOPMENTAL OUTCOME 
N/A 

UNIT STANDARD LINKAGES 
N/A 


Critical Cross-field Outcomes (CCFO): 

UNIT STANDARD CCFO IDENTIFYING 
Identify and solve problems
  • Selecting the correct components and accessories
  • Interpret manufacturer's catalogues 

  • UNIT STANDARD CCFO ORGANISING 
    Organize and manage myself and my activities responsibly and effectively
  • Select the correct manufacturer's catalogues 

  • UNIT STANDARD CCFO SCIENCE 
    Use science and technology effectively and critically
  • By understanding the processes involved
  • Identification of components and accessories
  • Appropriate use of conversion factors 

  • UNIT STANDARD ASSESSOR CRITERIA 
    N/A 

    REREGISTRATION HISTORY 
    As per the SAQA Board decision/s at that time, this unit standard was Reregistered in 2012; 2015. 

    UNIT STANDARD NOTES 
    This unit standard replaces unit standard 9520, "Explain function and operation of refrigeration circuits as applied to air-conditioning or refrigeration systems and select and explain the function of components, accessories and controls", Level 4, 8 credits.

    Supplementary information:

    Specific requirements are contained in one or more of the following documents:
  • Manufacturer's instructions.
  • Company procedures and guidelines. 

  • QUALIFICATIONS UTILISING THIS UNIT STANDARD: 
      ID QUALIFICATION TITLE PRE-2009 NQF LEVEL NQF LEVEL STATUS END DATE PRIMARY OR DELEGATED QA FUNCTIONARY
    Core  48966   Further Education and Training Certificate: Air-conditioning, Refrigeration and Ventilation  Level 4  NQF Level 04  Passed the End Date -
    Status was "Reregistered" 
    2009-03-12  Was MERSETA until Last Date for Achievement 


    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.
     
    1. IFIHLILE TRAINING ACADEMY GAUTENG (PTY) LTD (Halfway House)(TP) 



    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.