<p> NZQA unit standard 12449 version 5 Page 1 of 3</p><p>Title Demonstrate knowledge of gas combustion, burners, control systems, and flame protection</p><p>Level 4 Credits 15</p><p>Purpose People credited with this unit standard are able to: demonstrate knowledge of gas combustion and burner systems design; and demonstrate knowledge of gas burners, control systems, and flame protection systems.</p><p>Classification Gas Industry > Gas Utilisation Engineering</p><p>Available grade Achieved</p><p>Guidance Information</p><p>Definition Wobbe index is a number produced when the calorific value of a gas is divided by the square root of the relative density of that same gas.</p><p>Outcomes and performance criteria</p><p>Outcome 1</p><p>Demonstrate knowledge of gas combustion, and burner systems design.</p><p>Performance criteria</p><p>1.1 The combustion characteristics of gas are defined and related to gas burner systems design in terms of the principles of physics and chemistry.</p><p>Range Charles’ law, Boyle’s law, calorific value, gas composition, oxygen requirements, Wobbe index.</p><p>1.2 Heat transfer principles are defined and related to gas burner systems design in terms of industry usage.</p><p>Range conduction, convection, radiation.</p><p>1.3 The requirements for combustion are defined and their role explained in terms of physical laws.</p><p>Range fuel source, ignition source, oxygen.</p><p>MITO New Zealand Incorporated Ó New Zealand Qualifications Authority 2018 SSB Code 101542 NZQA unit standard 12449 version 5 Page 2 of 3</p><p>1.4 Causes of incomplete combustion are explained and the potential hazards identified in terms of industry practice.</p><p>Range lack of oxygen, chilling.</p><p>Outcome 2</p><p>Demonstrate knowledge of gas burners, control systems, and flame protection systems.</p><p>Performance criteria</p><p>2.1 Types of gas burner are described in terms of usage in domestic and industrial environments.</p><p>Range pre-aerated burners, post-aerated burners, pre-mix burners, forced draught burners, radiant burners.</p><p>2.2 Component parts of burners are described in terms of purpose and function.</p><p>Range injector, primary air port, aeration control shutter, venturi, venturi throat, throat restrictor, mixing tube, burner head, burner ports, retention ports.</p><p>2.3 Air injection systems are described in terms of natural draught and forced draught.</p><p>2.4 Faults in burner operation are described in terms of causes, and the steps to prevent them are described in accordance with company procedures.</p><p>Range unstable flame pattern, unsuitable gas flow rate, inadequate air supply, excessive air supply, linting.</p><p>2.5 Component parts of control systems for gas burners are described in terms of purpose, function, and industry usage.</p><p>Range isolation valves, control valves, governor, weep line, test cock, thermostat.</p><p>2.6 Control systems for gas burners are described in terms of pressure operated systems and electrically operated systems.</p><p>2.7 Types of flame protection system for gas burners are described in terms of purpose and industry usage.</p><p>Range bimetallic, vapour pressure, thermo-electric, flame conduction and rectification, photo-electric.</p><p>Planned review date 31 December 2019</p><p>MITO New Zealand Incorporated Ó New Zealand Qualifications Authority 2018 SSB Code 101542 NZQA unit standard 12449 version 5 Page 3 of 3</p><p>Status information and last date for assessment for superseded versions Process Version Date Last Date for Assessment Registration 1 25 September 1997 N/A Revision 2 3 August 2000 N/A Revision 3 10 October 2002 N/A Rollover and 4 20 November 2006 N/A Revision Revision and 5 17 August 2017 N/A Rollover</p><p>Consent and Moderation Requirements (CMR) reference 0014 This CMR can be accessed at http://www.nzqa.govt.nz/framework/search/index.do.</p><p>Comments on this unit standard</p><p>Please contact MITO New Zealand Incorporated [email protected] if you wish to suggest changes to the content of this unit standard.</p><p>MITO New Zealand Incorporated Ó New Zealand Qualifications Authority 2018 SSB Code 101542</p>