For highly sensitive injection systems – Super-clean fuel filters from Mann-Filter made in the cleanroom

Cleanroom seal

Filter in cleanroom production

Modern diesel engines and their injection systems are sensitive to contaminants and water in the fuel. Even microscopic particles can cause significant damage. Mann-Filter therefore offers fuel filters with high filtration precision and efficient water separation, reliably protecting all components. As cleanliness requirements increasingly apply to the components themselves, the company is producing more and more fuel filters for particularly high standards in cleanroom conditions at the Marklkofen production site. The filters produced in this way receive a purity seal and are available through the independent spare parts market in workshops and retail outlets.

The automotive industry has developed direct injection engines in recent years that precisely dose small amounts of fuel to keep consumption as low as possible. Such common-rail injections are delicate high-tech systems. The injection pump generates up to 2,500 bar pressure, the bores of the injection nozzles are smaller than 0.1 millimeters, almost as fine as a hair. Clean fuel is essential because even the tiniest dirt particles can cause serious damage to the injection system and reduce its performance. High-quality fuel can also be contaminated in Western industrial nations. Tiny metal or plastic shavings and other particles can enter during refueling, transport, storage, or through wear in the diesel. To protect the sensitive engine injection, the company offers fuel filters with ever higher filtration precision. They reliably remove particles in the range of a few micrometers—dirt that is barely visible to the naked eye. Dust particles are many times larger.

Component cleanliness: cleaning and being clean oneself
But the filter should not only clean the fuel; it should also be very clean itself. After all, many vehicle manufacturers now impose strict requirements for component cleanliness. Mann-Filter has therefore established the Component Cleanliness Management (CCM) within the company. The concept considers cleanliness requirements from the product development stage and throughout all processes—from procurement to manufacturing to delivery to the customer. "The filter supplies clean fuel to the high-pressure part of the injection system. However, it must already be clean on the inside when installed so that dirt particles do not disturb the highly sensitive system from the very first engine start," explains Melanie Michler, product manager for fuel filters at Mann-Filter. For the production of components with particularly high cleanliness requirements, the filter specialist at the Marklkofen plant has a state-of-the-art cleanroom manufacturing facility. Even large series can be produced in the cleanroom at the world's largest filter plant.

In the "white area," dust has no chance
The assembly of filter components takes place in a special room accessible only to trained personnel. Protective clothing is subject to strict hygiene regulations. Cleanroom shoes, a white laboratory coat, gloves, and a hairnet are mandatory. The room itself is certified according to EN ISO 14644. Ceilings, walls, and floors in the so-called "white area" are clad with dust-repellent powder-coated steel sheets, similar to those used in the pharmaceutical and food industries. Personnel may only use tools reserved for this area. The air pressure here is slightly higher to prevent dust ingress. Fibrous particles generated during production are immediately vacuumed away on-site. Filters leaving this cleanroom are protected on their clean side with the CCM seal.

Practical tip for workshops
Great care is required when installing fuel filters with the CCM seal. Michler recommends: "Retrieve the filter from storage only shortly before installation, then remove the purity seal and install the filter immediately. When replacing these filters, a clean environment and clean hands are crucial. It is also important to avoid additional dust in the immediate vicinity of the filter change. This effectively prevents contamination of the flow side."

Finer filtration, more dirt absorption, longer service life
Since 2009, the cleanroom production for Mann-Filter products in Marklkofen has increased tenfold. The filter element PU 9003, which is also produced there, is used among others for Volvo Cars. The automaker uses this fuel filter for its 2.4-liter diesel engines. The basis of the element is the high-performance filter medium MULTIGRADE F_HE. It removes at least 95 percent of dirt particles of size 0.004 millimeters or larger, according to ISO standard 19438, and more than 95 percent of water. With this medium, the company has developed a family of multilayer high-tech filter media that meet the ever-increasing requirements of automakers. The Ludwigsburg specialists achieve higher filtration precision by combining a cellulose carrier medium with a synthetic meltblown layer. When unfiltered fuel passes through the first layer of fine, meltblown plastic fibers, it then flows through a second, very dense layer of cellulose. The dirt absorption capacity is significantly improved compared to conventional cellulose media.

Tracking tiny water droplets
Diesel absorbs water from the surrounding air. Even tiny amounts of water in the fuel can damage downstream components such as pistons, cylinder heads, injection nozzles, fuel lines, and the injection pump, and limit engine performance. An almost complete water separation is therefore an important protection against corrosion. Here, too, the meltblown layer of the MULTIGRADE F medium performs thorough work thanks to its hydrophobic properties. Vehicles equipped with water sensors indicate in good time when the separated water should be drained. This is usually done via a drain screw on the filter housing. Additionally, Mann+Hummel's PU 9003 filter element contributes to environmental protection. It is completely metal-free, thermally fully incinerable, and thus environmentally friendly to dispose of.

A filter brand with 97 percent market coverage in Europe
With a market coverage of over 97 percent in Europe, the company offers the right filter for nearly every passenger car and transporter model. Mann-Filter products impress with OEM quality and quick availability.