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TWI -- True Worth Index [CLICK HERE FOR LATEST FIGURES] True Worth Index (TWI) (c) 2001, is a new Index proposed by Viswa Lab Corporation to indicate the true worth of a bunker fuel. Viswa Lab already calculates Engine Friendliness Number (EFN) (c) 2001 of every fuel that is tested. This number (from 1 to 100) indicates quality of the fuel from the point of view of wear and tear to the machinery. EFN has been widely accepted by the industry and used as a measuring tool for fuel quality. Bunker fuels are purchased and stemmed all over the world. The only quality requirement applicable to this fuel is based on ISO 8217. The specification for various grades provides a very broad range. It is therefore possible to get a bunker fuel, which in terms of its usefulness to the marine engine can vary widely and yet conform to the specifications. The three most important properties of the bunker fuel that determine its true worth to the marine engine are:
The difference in calorific value between very good fuel and very bad fuel is only 5% (41 MJ/Kg for very good fuel and 39 MJ/Kg for very bad fuel). Engine Friendliness Number can vary from 40 for an unfriendly fuel to 60 and above for a very friendly fuel. It is now generally accepted that CCAI is not a good indicator of the ignition quality of today's residual bunker fuel. Therefore, a FuelTech instrument, from Norway can be used to actually determine the ignition and combustion properties and present this data in the form of Equivalent Cetane Number (ECN). ECN of bad fuel will be less than 18.7 and those of good fuel can be 45 and above. Viswa Lab will assess the three properties namely, CV, EFN and ECN of fuels in different parts of the world where major bunkering activities take place. It will provide a basis for apportionment of the worth of the fuel based on these three properties. It will finally arrive at a True Worth Index, which will encompass all the three vital properties of the fuel and present this as a single number between 1 and 100.
It is hoped that over a period of time this number will become a benchmark on which commercial fuel transactions will be based. It will also provide an easy tool for those dealing with bunker fuel all across the bunker industry. It will reduce the need to go through the 26 parameters of the analysis test results, which are often confusing and contradictory to the layman. Viswa Lab hopes that the bunker industry will participate in using and providing suggestions in improving the accuracy and the usefulness of this index TWI (c) 2001.
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