Hi all I posted this to another list in response to claims that washing your biodiesel isn't necessary and that a less-than-complete reaction, glycs, contaminants, catalyst and excess methanol are good for you. Or something like that.
It hasn't been posted anywhere before, AFAIK. I'll cut all the other stuff off the bottom. Keith The Fuel Injection Equipment (FIE) Manufacturers (Delphi, Stanadyne, Denso, Bosch) issued a statement on biodiesel. They strongly support it, but they have their concerns too, and they're very involved in standards development. They had a fright in Europe in the early 90s when the introduction of low-sulphur diesel saw widespread damage to injection systems, with excessive wear and failure. The same thing happened in California. They don't want it to happen with biodiesel. These are their concerns: -Free methanol -Dissolved and free water -Free glycerin -Mono and di glycerides -Free fatty acids -Total solid impurity levels -Alkaline metal compounds in solution. -Oxidation and thermal stability They conducted extensive field trials with biodiesel in collaboration with end-users and found the following injection equipment and engine problems: -Corrosion of fuel injection equipment components. -Elastomeric seal failures -Low pressure fuel system blockage -Fuel injector spray hole blockage -Increased dilution and polymerisation of engine sump oil -Pump seizures due to high fuel viscosity at low temperatures -Increased injection pressure This is what caused problems: Free methanol in biodiesel Effect: Corrodes aluminium & zinc, Low flash point Failure Mode: Corrosion of fuel injection equipment Biodiesel process chemicals Effect: Potassium and sodium compounds, Solid particles Failure Mode: Blocked Nozzles Dissolved water in biodiesel Effect: Reversion of biodiesel to fatty acid Failure Mode: Filter Plugging Free water in mixtures Effect: Corrosion, Sustains bacteria, Increases the electrical conductivity of fuel Failure Mode: Sludging, Corrosion of fuel injection equipment Free glycerine, Mono-& di-glyceride Effect: Corrodes non ferrous metals, Soaks cellulose filters, Sediments on moving parts and Lacquering Failure Mode: Filter clogging, Injector Coking Free fatty acid Effect: Provides an electrolyte and hastens the corrosion of zinc, Salts of organic acids, Organic compounds formed Failure Mode: Corrosion of fuel injection equipment, Filter plugging, Sediments on parts Higher modulus of elasticity Effect: Increases injection pressure Failure Mode: Potential of reduced service life High viscosity at low temperature Effect: Generates excessive heat locally in rotary distributor pumps, Higher stressed components Failure Mode: Pump seizures, Early life failures, Poor nozzle spray Ageing products Corrosive acids (formic & acetic) Effect: Corrodes all metallic parts Failure Mode: Corrosion of fuel injection equipment Higher molecular organic acids Effect: Similar to fatty acid Failure Mode: Similar to fatty acid Polymerisation products Effect: Deposits especially from fuel mixes Failure Mode: Filter plugging, Lacquering formation in hot areas Engine manufacturers have similar concerns, especially with the oxidation of biodiesel leading to a gradual increase in contamination and free water content. I'm not sure what Kevin means by trying to attain to "a specification that tries to compare with its replacement." The standards are designed to match the engines and the fuel systems, not to match petro-diesel. The petro-diesel standards are also designed for the engines and the fuel systems, and petro-diesel doesn't always match it, especially in the US and Canada. The early bad experiences with low-sulphur petro-diesel were a case in point. The final ASTM specification D6751 is indeed based on the existing petro-diesel standard, D975, which was modified by elimination of items not applicable to biodiesel and by addition of items specific to biodiesel - not at all the same thing as Kevin's saying. A lot of work went into developing new analytical methods for a number of biodiesel properties. It isn't just a makeover of the petro standard, it's a biodiesel standard, and it's based on the hard realities of what bad fuel does to motors and fuel systems. The German draft standard DIN EN 14214, "Automotive fuels - Fatty acid methyl esters (FAME) for diesel engines - Requirements and test methods", is one of the most complete biodiesel specifications. The EU CEN technical committee TC19 is evolving European Standards and is liaising with the International Standards Organisation committee TC28 regarding an eventual world-wide standard. They're not just bumbling around. There's a huge increase in diesel use, very rapid advances in diesel technology, stringent requirements in improving diesel emissions, tremendous growth in biodiesel production. They're dealing with billions and billions of dollars, with entire transport systems. What they're definitely not going to say is No need to wash. They won't agree that prolonged settling will do instead - they'll say that's likely to result in biodegradation and formation of acids and free water content (what Kevin says Todd does by washing to try to accord with allegedly impractical standards - though I think Todd doesn't use acid in the wash, and has said so). They'll say "well produced unwashed ester" is a contradiction in terms. They do have "specific examples of damage caused by soap, caustic degradation, excess methanol", from both field studies and lab studies, all very revealing, yes. When they say "extensive" studies, that's what they mean, and they have the resources, expertise and interest to mean it. They'd be amused at the idea that the above by-products in anything above the standard limits would be "beneficial and enhancing to the injection system, the injectors, the combustion chamber, the fuel tank and the ring support systems". Or maybe they wouldn't be amused at all. Well, that goes for their chief engineers, technical directors, standards people and so on. Their sales teams would probably be chortling with delight though - good business coming their way. Well, business, if not "good" business. Anyway, we can all do whatever we like, but it's quite possible for a homebrewer to make standard spec fuel, in fact it's easy, so why not do it? That's what most people are doing, or trying to, and they'll succeed. But, if you want to know better than Stanadyne et al, that's your prerogative. Keith Biofuels at Journey to Forever http://journeytoforever.org/biofuel.html Biofuel at WebConX http://webconx.green-trust.org/2000/biofuel/biofuel.htm List messages are archived at the Info-Archive at NNYTech: http://archive.nnytech.net/ To unsubscribe from this group, send an email to: [EMAIL PROTECTED] Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
