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The NOx emission compliance can be determined by checking few parameters and records.

Engine International Air Pollution Prevention Certificate (EIAPP)

EIAPP certificate must be present on board. And this certificate needs to be for each of the diesel engines more than 130KW on board as NOx requirements are applicable for diesel engines more than 130KW power.

 If a ship is fitted with one main engine and three auxiliary engines (generators). There needs to be EIAPP certificate for all these.

EIAPP certificate is issued after the engine is found to be complying with the NOx emission requirements during the pre-certification survey. The pre-certification means the survey done before fitting the engine on board the ship.

Having an EIAPP certificate on board shows that the engine fitted on board was complying with the NOx parameters and an engine of correct specifications was fitted on board.

International Air pollution prevention certificate (IAPP)

After the engines are fitted on the ship, the test is again done on the engines for compliance with the NOx criteria.

This test is required because when the engine is fitted on board ships, some changes/modifications might have been done on the engines.

This test proves that the engine still complies with the NOx requirements even after fitting on the ship.

If the engines are found to in compliance with the NOx criteria of annex VI, International air pollution prevention certificate is issued to the ship.

NOx on board Verification

Having EIAPP and IAPP certificates on board proves that the engine of the correct specification is fitted on board.

It proves that when the engine was fitted on board, the NOx emissions from the engine were within limits and as required by MARPOL annex VI.

But after 10 or 20 years in operation, There are three ways in which ship can prove that it still complies with the NOx requirements.

• Engine Parameter Check method
• Simplified Measurement method
• Direct Measurement and Monitoring method

The method that the ship is certified to use for on board verification of NOx is specified in the EIAPP certificate of the engine.

And the procedure to verify on board compliance (and using the certified method) is provided in the NOx technical file that accompany the EIAPP certificate of the engine.

The “simplified measurement” and “Direct measurement and monitoring” methods are based on measuring the NOx emissions from the engine.

Engine parameter check method

This method is based on the principle that if the engine complied with the NOx parameters at the time it was fitted on board, it should continue to comply if there are no modifications/adjustment made to the engine.

There no extra costs involved to use this method, this method is most common among ship owners.

So there are few things that are required from this method

• the engine parts that contribute to the NOx emission. Modification and adjustments of these parts must be as per the Maker’s guidelines.
• If any of these spare parts of the engine need to be changed, it must be changed with the original part supplied by the maker.
• Any adjustments made to these parts must be within the range specified by the maker of the engine.
• A record must be kept for all the replacements of the spare parts and all the adjustments made to these parts.

Durning annual, intermediate and renewal survey of the Air pollution prevention certificate, these records, and engine parameters are checked by the class surveyor.

The international air pollution prevention certificate is endorsed or renewed on the basis of these verifications by the class surveyor.

NOx Technical file

NOx Technical File is a record containing all details of parameters, including components and settings of an engine, which may influence the NOx emission of the engine.

To use engine parameter check method, the parameters of the engines need to be same throughout the life of the engine.

There is one NOx technical file for each engine for which an EIAPP certificate is issued.

NOx technical file contains information about

     identification of those components, settings and operating values of the engine which influences its NOx emissions

     Allowable adjustments on the engine

     on board NOx verification procedures to verify compliance with the NOx emission limits during on board verification surveys

     Full record of the relevant engine’s performance, including engines rated speed and rated power.

     Emission test report.

     Designation and restriction for an engine which is a member of engine group or engine family.