4.3.8 Guidelines for the selection 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 - 4.3.8 Guidelines for the selection of an engine family

4.3.8 Guidelines for the selection of an engine family

  4.3.8.1 The engine family shall be defined by basic characteristics which must be common to all engines within the 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 aspiration 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 a family. The following basic characteristics, but not specifications, must 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/heavy fuel oil
    • dual 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

  4.3.8.3 If there are engines which incorporate other features which 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 family.

Parent topic: 4.3 Application of the engine family concept
Copyright 2022 Clasifications Register Group Limited, International Maritime Organization, International Labour Organization or Maritime and Coastguard Agency. All rights reserved. Clasifications Register Group Limited, its affiliates and subsidiaries and their respective officers, employees or agents are, individually and collectively, referred to in this clause as 'Clasifications Register'. Clasifications Register assumes no responsibility and shall not be liable to any person for any loss, damage or expense caused by reliance on the information or advice in this document or howsoever provided, unless that person has signed a contract with the relevant Clasifications Register entity for the provision of this information or advice and in that case any responsibility or liability is exclusively on the terms and conditions set out in that contract.