Diesel Fuel In the '90s
Diesel fuel quality is declining throughout the world, and we expect this trend to continue. In fact, a recent survey suggests that 70% of diesel fuel sold at service stations does not meet the Society of Automotive Engineers' (SAE) standard for diesel fuel lubricity. The three leading factors affecting fuel are:
- Crude oil sources- Refining techniques, and- Blending techniques
Crude Oil Sources - In the past, crude oils were selected with the end product in mind because certain crudes lend themselves to producing high quality fuels and others do not. As crude oils become more scarce, the ability to carefully select specific crudes is less economically feasible and compromises are made.
Blending - The third factor affecting fuel quality is blending. In cold weather conditions, for example, many refiners blend kerosene (or number 1 diesel) with number 2 diesel to lower the temperature at which the fuel starts to gel. This has the undesirable effect of reducing the energy content of the fuel, resulting in a decrease in fuel economy. It also may adversely effect the fuel's lubricating and performance properties resulting in potential wear on vital engine components. In many diesel fuel injection systems, the fuel itself is the only lubricant for the precision engineered injection pump.
Basics ofFuel Filtration
Proper filtration of diesel fuel is critical to maintaining the performance and long life of a diesel engine. In order to produce and control the extremely high injection pressures common in a diesel, the injection pump components and nozzles are machined to extremely close tolerances - often measured in microns (one micron is 40 millionths of an inch). To prevent the premature failure of these vital components, it is critical that diesel fuel be filtered to remove extremely small particles of foreign matter. The particles that a secondary or final fuel filter, for example, are in the range of 5-10 microns (.0002 - .0004"). To illustrate how small these tolerances are, consider that:
• The naked eye cannot see particles smaller than 40 microns.• A grain of sand is approximately 100 microns.• A human hair is approximately 70 microns.• A single grain of talcum powder is 10 microns.
Leading OEMs such as General Motors, Caterpillar, John Deere, and Perkins specify Stanadyne's Fuel Manager™ to protect their engines. Follow their lead and fit a Fuel Manager™ filter/separator to your vehicle for additional protection. An added benefit of the Fuel Manager™ is its modular design with see-thru water collection bowl, fuel heater, electronic water-in-fuel sensor and other options.
Water In Fuel
The greatest enemy of diesel fuel injection components is water. Once water enters the fuel system, it will rapidly wear and oxidize steel components and lead to:
• Rusting and corrosion of components• Governor/metering component failure• Sticky metering components (both pump and nozzle)• Injection component wear and seizure
Water contamination can exist in diesel fuel in three forms:
1) Emulsified water, where the water is suspended in the fuel like oil and vinegar in salad dressing.
2) Free water, where the water is separated from the fuel and usually is found on the bottom of fuel/storage tanks.
3) Dissolved water, where the water has been chemically dissolved in the fuel, like sugar in coffee. The warmer the fuel, the more water will be dissolved, but as temperatures drop, the water will come out of the solution in the form of free water.
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