• MANN-FILTER PU 12 004 z diesel fuel filter available from now on as a set with fuel prefilter for the independent automotive aftermarket • Thanks to three-stage water separation, filter separates over 90 percent of the water in the fuel
Ludwigsburg, July 22, 2020 – Even high-quality diesel may contain traces of water, whether from moist air entering through the tank ventilation or from condensation in the large tanks used to store the diesel in gas stations. However, advanced common rail diesel injection systems with injection pressures of up to 2,500 bar have higher requirements than simple mechanical systems in terms of the purity of the fuel.
Tiny dirt particles and water drops can damage the components of the fuel circuit, which in the worst case can result in system failure. Another challenge is the composition of modern diesel fuels, which have changed greatly in recent years: they contain very little sulfur and have higher proportions of biofuel and additives. This results in the formation of very small and stable water drops in the diesel fuel and requires a new water separation technology.
Three-stage water separation protects injection system
If water enters the fuel circuit, it is reduced to small drops in the low-pressure fuel pump. After several fuel cycles, drop sizes smaller than 1/10th the diameter of a human hair are possible. MANN+HUMMEL has developed a solution for removing these very small and finely distributed water droplets from the diesel fuel. Fuel flows through the MANN-FILTER PU 12 004 z diesel fuel filter from the outside to the inside in three stages. This is referred to as pressure-side filter operation.
In the first stage, the filter medium reliably removes solid dirt particles from the diesel fuel. The second filter stage uses a coalescer fleece. It retains even the finest water droplets from the fuel/water emulsion and combines them to form much larger drops. In the third stage, a hydrophobic sieve ensures that the enlarged drops do not enter the injection system. Gravity causes the separated water to collect in a water collection chamber in the filter module. A sensor signals as soon as the water needs to be manually drained or siphoned.
The MANN-FILTER PU 12 004 z separates over 90 percent of water droplets from current gas station diesel fuels, even in the case of tiny water droplets of up to ten micrometers. It works right up to the end of the service interval, even with a loaded filter element. Both single-stage and two-stage concepts on the market achieve relatively low separation efficiency of up to a maximum of 35 to 40 percent and therefore do not provide reliable protection for modern injection systems.
Can be recycled to protect the environment and available as a set
The new fuel filter will be available from now on for the independent automotive aftermarket in 100 percent OE quality. In conjunction with the PU 5003 prefilter, which protects the low-pressure pump, it will be available as the PU 12 010-2 z set for the Mercedes-Benz Actros, Heavy-Duty Engine Platform HDEP. Metal-free elements mean that both filters are completely incinerable and therefore can be recycled to protect the environment.
A PreLine prefilter is currently in planning for regions whose fuel quality is affected by high particle and water contamination. This is mounted on the intake side, also operates with three-stage water separation and ensures optimal protection of the engine.
Service-friendly, patented concept when changing the filter
When the mechanic turns the cover during removal of the filter, the retaining bracket of the element end plate connect firmly with their mating parts in the cover. When unscrewing, this bayonet bracket ensures that the entire filter element releases and lifts up from the connection in the housing without the usual force. This makes removal in the workshop much easier. When installing the new filter element, it must be engaged by turning it slightly. The company has obtained patents in a number of countries for the filter element with bayonet bracket.
"Whether corrosion or cavitation effects in injectors, valves, or the CR-system high-pressure pump, this innovative separation technology greatly reduces damage that can result in system failure," says Martin Veit, Lead Product Engineer Fuel Filters Development in MANN+HUMMEL's Automotive Aftermarket business unit. MANN+HUMMEL has filed several patents for the new filter technology with the German Patent and Trademark Office as well as in other countries.