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: 

Demonstrate knowledge of the refrigeration system operating on ammonia 
SAQA US ID UNIT STANDARD TITLE
9444  Demonstrate knowledge of the refrigeration system operating on ammonia 
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 
Design, select, install, commission and operate ammonia refrigeration systems. 

LEARNING ASSUMED TO BE IN PLACE AND RECOGNITION OF PRIOR LEARNING 
Explain the operation of the vapour compression cycle, and identify and explain the operation of the components and the associated controls, safety devices and defrost systems.
Explain the precautions to be taken with refrigeration oils and how oil can be used to indicate the condition of a refrigeration system.
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.
Plot the multi-stage refrigeration cycle on a pressure-enthalpy diagram and explain its operation. 

UNIT STANDARD RANGE 
Single, multi-stage and compound ammonia systems. 

Specific Outcomes and Assessment Criteria: 

SPECIFIC OUTCOME 1 
Explain the operation of ammonia refrigerant systems. 

ASSESSMENT CRITERIA 

ASSESSMENT CRITERION 1 
1. A block diagram of the main components and accessories is drawn. 

ASSESSMENT CRITERION 2 
2. The purpose and function of all components and accessories is explained. 

ASSESSMENT CRITERION 3 
3. The operation of ammonia refrigerant systems is explained. 

ASSESSMENT CRITERION 4 
4. The properties of ammonia refrigerant are explained. 
ASSESSMENT CRITERION RANGE 
Chemical, thermodynamic and physical.
 

ASSESSMENT CRITERION 5 
5. The advantages and limitations of ammonia as refrigerant are discussed. 

ASSESSMENT CRITERION 6 
6. The principles of two-phase flow (ammonia liquid-vapour) is explained. 

ASSESSMENT CRITERION 7 
7. The oil/ammonia relationship in ammonia refrigerant systems is explained. 

ASSESSMENT CRITERION 8 
8. Safety precautions to be adhered to when operating ammonia systems are discussed. 

SPECIFIC OUTCOME 2 
Design liquid ammonia pumped re-circulation system and piping. 

ASSESSMENT CRITERIA 

ASSESSMENT CRITERION 1 
1. The principles of liquid re-circulation are evaluated and its merits and limitations explained. 

ASSESSMENT CRITERION 2 
2. The sizing, selection and positioning of the ammonia liquid pump is carried out from manufacturers' catalogues and/or computerised data. 

ASSESSMENT CRITERION 3 
3. Ammonia pump cavitation and methods to prevent it are explained. 

ASSESSMENT CRITERION 4 
4. Requirements of liquid re-circulation piping and defrost piping are explained. 

ASSESSMENT CRITERION 5 
5. Sizing of refrigerant piping is correctly undertaken. 
ASSESSMENT CRITERION RANGE 
Liquid, vapour, liquid/vapour and defrost gas lines.
 

ASSESSMENT CRITERION 6 
6. Design principles of surge drum (liquid separator) sizing are explained and sizing is correctly undertaken. 

ASSESSMENT CRITERION 7 
7. Diagrammatic layouts of ammonia liquid re-circulation systems are correctly undertaken. 

ASSESSMENT CRITERION 8 
8. The philosophy of piping material selection for ammonia systems is explained. 

ASSESSMENT CRITERION 9 
9. Methods of pipe sizing and valve selection are explained and correctly undertaken. 
ASSESSMENT CRITERION RANGE 
Pressure drop data and/or computerised programs.
 

SPECIFIC OUTCOME 3 
Select liquid ammonia pumped re-circulation system and piping. 

ASSESSMENT CRITERIA 

ASSESSMENT CRITERION 1 
1. The method of liquid control is explained and selection and operation of liquid control valves is demonstrated. 

ASSESSMENT CRITERION 2 
2. Standard practices regarding pipe location are explained. 

ASSESSMENT CRITERION 3 
3. Methods of oil separation, collection and return are listed and explained. 

ASSESSMENT CRITERION 4 
4. Recommendations for the selection of pipefittings and joints are discussed. 

SPECIFIC OUTCOME 4 
Select the main components for ammonia systems. 

ASSESSMENT CRITERIA 

ASSESSMENT CRITERION 1 
1. Reasons for compressor cooling are discussed. 

ASSESSMENT CRITERION 2 
2. Compressor cooling methods are listed and explained including their merits and limitations. 

ASSESSMENT CRITERION 3 
3. Sizing and selection of condenser, receivers and evaporators is carried out given manufacturers' data and catalogues and/or computerised programs. 

ASSESSMENT CRITERION 4 
4. Locating condensers, receivers, and evaporators and design of interconnecting piping is explained. 
ASSESSMENT CRITERION RANGE 
Single and parallel operation of condensers, receivers and evaporators.
 

ASSESSMENT CRITERION 5 
5. The method to determine the refrigerant charge of ammonia systems explained and demonstrated. 

SPECIFIC OUTCOME 5 
Design and select compound ammonia refrigeration systems. 

ASSESSMENT CRITERIA 

ASSESSMENT CRITERION 1 
1. The principles of operation of compound ammonia systems are explained. 

ASSESSMENT CRITERION 2 
2. The application and operation of gas and liquid intercooling is explained. 

ASSESSMENT CRITERION 3 
3. The design principles of compound ammonia systems are explained and demonstrated. 

ASSESSMENT CRITERION 4 
4. The components for compound refrigeration systems are selected. 


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 
  • Identifying requirements of ammonia systems
  • Identifying applications of ammonia systems
  • Refrigerant pump cavitation and methods of prevention
  • Safety requirements when using ammonia
  • Knowledge of Occupational Health and Safety Act
  • Safe handling of refrigerants
  • Knowledge of thermodynamic properties of ammonia refrigerant, ammonia vapour/liquid two-phase flow, ammonia-oil relationship 
    		•


    Critical Cross-field Outcomes (CCFO): 

    UNIT STANDARD CCFO IDENTIFYING 
    Identify and solve problems
  • Identifying requirements for ammonia systems and selection 
    		•

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

    UNIT STANDARD CCFO ORGANISING 
    Organize and manage myself and my activities responsibly and effectively
  • Selecting correct design method and procedures 
    		•

    UNIT STANDARD CCFO SCIENCE 
    Use science and technology effectively and critically
  • Design principles for ammonia plant and components 
    		•

    UNIT STANDARD CCFO DEMONSTRATING 
    Demonstrate an understanding of the world as a set of related systems
  • Be aware of the effect of leakage of refrigerants on the environment 
    		•

    UNIT STANDARD CCFO CONTRIBUTING 
    Learner and societal development
  • By learning how to design ammonia refrigeration systems 
    		•

    UNIT STANDARD NOTES 
    Specific requirements are contained in one or more of the following documents:
  • Manufacturer`s instructions and technical information regarding the selection of components.
  • Company procedures and guidelines.

    Legal requirements are contained in:
  • Occupational Health and Safety Act.
  • Code of Practice for the Safe Handling of Refrigerants.
  • Standard safety precautions when using ammonia. 
    		•

    QUALIFICATIONS UTILISING THIS UNIT STANDARD: 
      ID QUALIFICATION TITLE PRE-2009 NQF LEVEL NQF LEVEL STATUS END DATE PRIMARY OR DELEGATED QA FUNCTIONARY
    Elective  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.