4.3 Application of the engine family concept
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Statutory Documents - IMO Publications and Documents - International Codes - NOx Technical Code (2008) - Technical Code on Control of Emission of Nitrogen 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 Application of the engine family concept

  4.3.1 The engine family concept provides the possibility of reducing the number of engines that must be submitted for approval testing, while providing safeguards that all engines within the engine family comply with the approval requirements. In the engine family concept, engines with similar emission characteristics and design are represented by a parent engine.

  4.3.2 Engines that are series-produced and not intended to be modified may be covered by the engine family concept.

  4.3.3 The selection procedure for the parent engine is such that the selected engine incorporates those features that will most adversely affect the NOx emission level. This engine, in general, shall have the highest NOx emission level among all of the engines in the engine family.

  4.3.4 On the basis of tests and engineering judgement, the manufacturer shall propose which engines belong to an engine family, which engine(s) produce the highest NOx emissions, and which engine(s) should be selected for certification testing.

  4.3.5 The Administration shall review for certification approval the selection of the parent engine within the engine family and shall have the option of selecting a different engine, either for approval or production conformity testing, in order to have confidence that all engines within the engine family comply with the applicable NOx emission limit.

  4.3.6 The engine family concept does allow minor adjustments to the engines through adjustable features. Marine diesel engines equipped with adjustable features must comply with all requirements for any adjustment within the physically available range. A feature is not considered adjustable if it is permanently sealed or otherwise not normally accessible. The Administration may require that adjustable features be set to any specification within its adjustable range for certification or in-use testing to determine compliance with the requirements.

  4.3.7 Before granting an engine family approval, the Administration shall take the necessary measures to verify that adequate arrangements have been made to ensure effective control of the conformity of production. This may include, but is not limited to:

  • .1 the connection between the NOx critical component part or identification numbers as proposed for the Engine Family and the drawing numbers (and revision status if applicable) defining those components;

  • .2 the means by which the Administration will be able, at the time of a survey, to verify that the drawings used for the production of the NOx critical components correspond to the drawings established as defining the engine family;

  • .3 drawing revision control arrangements. Where it is proposed by a manufacturer that revisions to the NOx critical component drawings defining an engine family may be undertaken through the life of an engine, then the conformity of production scheme would need to demonstrate the procedures to be adopted to cover the cases where revisions will, or will not, affect NOx emissions. These procedures shall cover drawing number allocation, effect on the identification markings on the NOx critical components and the provision for providing the revised drawings to the Administration responsible for the original engine family approval. Where these revisions may affect the NOx emissions the means to be adopted to assess or verify performance against the parent engine performance are to be stated together with the subsequent actions to be taken regarding advising the Administration and, where necessary, the declaration of a new parent engine prior to the introduction of those modifications into service;

  • .4 the implemented procedures that ensure any NOx critical component spare parts supplied to a certified engine will be identified as given in the approved technical file and hence will be produced in accordance with the drawings as defining the engine family; or

  • .5 equivalent arrangements as approved by the Administration.

4.3.8 Guidance for the selection of an engine family

4.3.8.1 The engine family shall be defined by basic characteristics that must be common to all engines within the engine family. In some cases there may be interaction of parameters; these effects must also be taken into consideration to ensure that only engines with similar exhaust emission characteristics are included within an engine family, e.g., the number of cylinders may become a relevant parameter on some engines due to the charge air or fuel system used, but with other designs, exhaust emissions characteristics may be independent of the number of cylinders or configuration.

4.3.8.2 The engine manufacturer is responsible for selecting those engines from their different models of engines that are to be included in an engine family. The following basic characteristics, but not specifications, shall be common among all engines within an engine family:

  • .1 combustion cycle:

    • - 2-stroke cycle

    • - 4-stroke cycle

  • .2 cooling medium:

    • - air

    • - water

    • - oil

  • .3 individual cylinder displacement:

    • - to be within a total spread of 15%

  • .4 number of cylinders and cylinder configuration:

    • - applicable in certain cases only, e.g., in combination with exhaust gas cleaning devices

  • .5 method of air aspiration:

    • - naturally aspirated

    • - pressure charged

  • .6 fuel type:

    • - distillate/residual fuel oil

    • - dual fuel

    • - gas fuel

  • .7 combustion chamber

    • - open chamber

    • - divided chamber

  • .8 valve and porting, configuration, size and number:

    • - cylinder head

    • - cylinder wall

  • .9 fuel system type:

    • - pump-line-injector

    • - in-line

    • - distributor

    • - single element

    • - unit injector

    • - gas valve

  • .10 miscellaneous features:

    • – exhaust gas re-circulation

    • – water/emulsion injection

    • – air injection

    • – charge cooling system

    • – exhaust after-treatment

    • – reduction catalyst

    • – oxidation catalyst

    • – thermal reactor

    • – particulates trap.

  • .11 ignition methods:

    • – compression ignition

    • – ignition by pilot injection

    • – ignition by spark plug or other external ignition device

4.3.8.3 If there are engines that incorporate other features that could be considered to affect NOx exhaust emissions, these features must be identified and taken into account in the selection of the engines to be included in the engine family.

4.3.9 Guidance 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 that incorporates engine features and characteristics that, from experience, are known to produce the highest NOx emissions expressed in grams per kilowatt hour (g/kWh). This requires detailed knowledge of the engines within the engine family. Under certain circumstances, the Administration may conclude that the worst case NOx emission rate of the engine family can best be characterized by testing a second engine. Thus, the Administration may select an additional engine for test based upon features that indicate that it may have the highest NOx emission levels of the engines within that engine family. If the range of engines within the engine family incorporate other variable features that 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 parent engine shall have the highest emission value for the applicable test cycle.

4.3.10 Certification of an engine family

4.3.10.1 The certification shall include a list, to be prepared and maintained by the engine manufacturer and approved by the Administration, of all engines and their specifications accepted under the same engine family, the limits of their operating conditions and the details and limits of engine adjustments that may be permitted.

4.3.10.2 A pre-certificate, or EIAPP Certificate, shall be issued for a member engine of an engine family in accordance with this Code that certifies that the parent engine meets the applicable NOx limit specified in regulation 13. Where member engine pre-certification requires the measurement of some performance values, the calibration of the equipment used for those measurements shall be in accordance with the requirements of 1.3 of appendix 4 of this Code.

4.3.10.3 When the parent engine of an engine family is tested and gaseous emissions measured under the most adverse conditions specified within this Code and confirmed as complying with the applicable maximum allowable emission limits as given in 3.1, the results of the test and NOx measurement shall be recorded in the EIAPP Certificate issued for the particular parent engine and for all member engines of the engine family.

4.3.10.4 If two or more Administrations agree to accept each other’s EIAPP Certificates, then an entire engine family, certified by one of these Administrations, shall be accepted by the other Administrations which entered into that agreement with the original certifying Administration, unless the agreement specified otherwise. Certificates issued under such agreements shall be acceptable as prima facie evidence that all engines included in the certification of the engine family comply with the specific NOx emission requirements. There is no need for further evidence of compliance with regulation 13 if it is verified that the installed engine has not been modified and the engine adjustment is within the range permitted in the engine family certification.

4.3.10.5 If the parent engine of an engine family is to be certified in accordance with an alternative standard or a different test cycle than allowed by this Code, the manufacturer must prove to the Administration that the weighted average NOx emissions for the appropriate test cycles fall within the relevant limit values under regulation 13 and this Code before the Administration may issue an EIAPP Certificate.

Parent topic: Chapter 4 - Approval for serially manufactured engines: engine family and engine group concepts
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