.1 definition of continuous NOx monitoring, taking into account both steady state and transitional operation of the engine;
.2 data recording, processing and retention;
.3 a specification for the equipment to ensure that its reliability is maintained during service;
.4 a specification for environmental testing of the device;
.5 a specification for the testing of the equipment to demonstrate that it has a suitable accuracy, repeatability and cross sensitivity compared with the applicable sections of this Code; and
.6 the form of approval certificate to be issued by the Administration.
2 Procedure to achieve such Guidelines: priorities proposed by Euromot
Euromot suggests to give priority to the requirements in .1, .3 and possibly .2 above, to achieve a commonly accepted definition for "continuous monitoring" in the context of the NOx Technical Code, and the specification of the equipment as a consequence of this definition.
Furthermore, the purpose and the quality of data recording and, above all, of the data storage for control or check-up has to be clearly identified.
This stepwise procedure is not only logical but is also important to be clear about the cost implications for shipbuilders and ship operators.
In any case, the guidelines have to observe the possibly rough operating conditions of a monitoring device installed on a ship and the restricted personnel skill to operate it, both very diiferent from the measuring procedures in a laboratory or during certification.
Topics .4, .5 and .6 above may be evaluated in a second step, i.e. after having achieved a clear definition of the basic purposes and requirements.
3 Definition of continuous NOx monitoring and consequent requirement on the recording equipment
3.1 "Monitoring" is to mean that sufficient recording shall be taken from the exhaust of an individual engine under conditions as near as possible to steady loading to he able to detect any significant change in the concentration of the emission. Consequently, it is not to be understood as a direct measurement of NOx emissions. Emissions have been measured during the engine and vessel certification process. For the ship operation it has only to be ensured that possible changes to higher emissions are detected. Therefore, monitoring should be restricted to identify changes or gradients, not absolute values. This definition may avoid that the ship operator is obliged to run sophisticated laboratory devices by a specially educated operator.
The graph attached at annex illustrates that NOx monitoring builds upon initial NOx measurement is not just a repetition but a simplified indication of changes.
3.2 "Continuous" should mean once every [100 ± 10] hours during [30] min. There is no need to determine the NOx level "continuously" in the narrow meaning of the term. This reflects in practice that a single instrument would be sufficient to measure and record emissions from a multiple engine installation. The frequency of measurements should allow for short periods when equipment is out of service for calibration and routine maintenance. Furthermore for unmanned engine-rooms it should only be necessary to take measurements at times when suitable staff are available.
