Advances in engine technology to meet stringent emission regulations have led to the broad adaptation of high pressure common rail (HPCR) systems with high-performance fuel injection technology. Changes to the HPCR make fuel systems much more susceptible to damage from contaminants including hard particles.
Hard particle contamination can cause several problems in the fuel system. Damage to moving parts can lead to starting problems, poor engine performance, idling issues and potentially complete engine failure. They can also affect the spray pattern generated by the HPCR injector, which is critical for proper combustion and overall fuel system performance. Injectors must be extremely precise in terms of quantity, distribution and timing. Damage from erosive wear can cause overfueling, which leads to decreased fuel efficiency. Pump performance can also be compromised by scoring and abrasive wear.
In modern engines, these issues are magnified by tighter tolerances and extreme HPCR pressures, in the 2,000 - 3,000 bar / 29,000 - 44,000 psi range. In fact, a Southwest Research Institute study completed in 2011 with industry participation established that particles in 2 to 3 microns range (in comparison, the average diameter of human hair is 80 microns) produced mechanical damage to high-pressure fuel injectors in a 1,700 bar / 25,000 psi HPCR system. In contrast, a study completed in 2000 by a similar group of participants established that unit injectors experienced abrasive wear due to particles 6 to 7 microns and larger.
These two studies illustrate that what was considered high efficiency in the past may not cut it today; in the past, 95 percent or 98 percent efficiency may have been considered good enough for 4 micron particles. Today, however, we are measuring high efficiency closer to 99.9 percent. The fraction of a percentage point can make a difference on whether a filtration system can achieve the fuel cleanliness requirements for the HPCR components or not.
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Today, advanced fuel filtration media formulations use more synthetics and synthetic/micro-glass formulations. They rely on multi-layer structures to achieve high efficiency and long life by allowing effective storage of both hard and soft particles in the media. This is a key area of fuel filter performance differentiation. As the high-efficiency filter picks up more fine contaminants, what may have passed through a filter in previous years may now be a contributing factor to plugging today’s tighter filters. Along with cost-effectiveness and efficient use of engine space, advanced media formulations that increase contaminant holding capacity within the same package size are critical to delivering service intervals without compromising the fuel cleanliness requirements of HPCR suppliers.
Proven media technologies like Synteq XP used in Donaldson Blue fuel filters deliver the highest levels of efficiency and contaminant retention under dynamic conditions. This technology relies on an engineered blend of fine fibers with a proprietary, resin-free bonding system achieved using bicomponent fibers.
The old saying that "all filters are not created equal" rings truer than ever, making it more important to understand what is hidden underneath the surface of the filter.
