4.3.9 Guidelines for selecting the parent engine of an engine family
Clasification Society 2024 - Version 9.40
Statutory Documents - IMO Publications and Documents - International Codes - NOx Technical Code - Technical Code on Control of Emission of Nitrous Oxides from Marine Diesel Engines - Chapter 4 - Approval for serially manufactured engines: engine family and engine group concepts - 4.3 Application of the engine family concept - 4.3.9 Guidelines for selecting the parent engine of an engine family

4.3.9 Guidelines for selecting the parent engine of an engine family

  4.3.9.1 The method of selection of the parent engine for NOx measurement shall be agreed to and approved by the Administration. The method shall be based upon selecting an engine which incorporates engine features and characteristics which, from experience, are known to produce the highest NOx emissions expressed in grammes per kilowatt hour (g/kW h). This requires detailed knowledge of the engines within the family. Under certain circumstances, the Administration may conclude that the worst case NOx emission rate of the family can best be characterized by testing a second engine. Thus, the Administration may select an additional engine for test based upon features which indicate that it may have the highest NOx emission levels of the engines within that family. If engines within the family incorporate other variable features which could be considered to affect NOx emissions, these features must also be identified and taken into account in the selection of the parent engine.

  4.3.9.2 The following criteria for selecting the parent engine for NOx emission control shall be considered, but the selection process must take into account the combination of basic characteristics in the engine specification:

  • .1 main selection criteria

    • higher fuel delivery rate

  • .2 supplementary selection criteria

    • higher mean effective pressure
    • higher maximum cylinder peak pressure
    • higher charge air/ignition pressure ratio
    • dp/dα, the lower slope of the combustion curve
    • higher charge air pressure
    • higher charge air temperature

  4.3.9.3 If engines within the family incorporate other variable features which may affect the NOx emissions, these features must also be identified and taken into account in the selection of the parent engine.

Parent topic: 4.3 Application of the engine family concept
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