The atmospheric temperature (the absolute temperature of the intake air) conform to the temperature range of Japanese climates, for example, about 50 days in all the year as shown on Figure 3.
For the marine engine having comparatively bigger output, it is difficult to provide test bed which is able to control temperature and humidity of the intake air within the required range, and in consequence, the test for engine family approval can only be carried out in a limited period under the Japanese climates condition.
When the allowable range of the test condition parameter "fa" is able to consider to be increased with necessary correction, the test for engine family approval is able to be carried out flexibly almost all year round.
Engine production condition and test bed
3 The typical engine family is the engine for automobile use (from tens kW to hundreds kW output) and for non road use (such as construction machines and agricultural machines, from a few kW to hundreds kW output), used for marine engines, produced in series.
Not only emission of NOx but also other gas emissions, smoke and particulate emissions (PT) of these engine family shall conform to the requirements of the limited level for automobile engines and non road use engines. The production factories produce them in series (annual production of thousands of units and in some cases hundreds of thousands of units), and they have test beds in test rooms where temperature and humidity are able to be controlled and tests can be carried out under the conditions of temperature and humidity that conform to the required range of test parameter "fa".
4 The engines (from hundreds kW to thousands kW output) for mainly marine auxiliary use, propulsion use and land electric power plant use are also the one of the typical engine family. This marine use engine family is designed to be able to burn both distillate fuel oil and heavy fuel oil, and it includes bigger engines and less production numbers compared with the engine family of the above paragraph 3. The production scale of this type of engine (about 1,000 units annually even at a large factory) is smaller than that of the engines for on road use and non road use (from thousands units to hundreds thousands units), and it is impossible to provide temperature controlled test beds due to its bigger size and output.
5 The marine auxiliary engine for generating plant requires the constant revolution by the generator and required output is decided depending on generator capacity. Therefore, this type of engine does not require even minor adjustments and modifications (specified concept as engine group), and is operated during her life time as an original product without any alterations (specified concept as engine family). The marine auxiliary use engine shall be classified as one of the engine family in accordance with the following concepts.
.1 Engine family concept.
Engines that are series produced, and not intended to be modified may be covered by the engine family concept. (NOx Technical Code paragraph 4.3.2)
