photo: Wikimedia Commons/Illustrative photo
RAILTARGET follows a UIC webinar on fuel filtration for internal combustion engines, covering fuel quality, new filtration technologies, preventive maintenance, and operating costs, with practical examples of how better filtration can improve engine reliability and performance across rail operations.
9:30 David Chambrier of UIC opens the session and briefly introduces MANN+HUMMEL before handing over to the company’s team. MANN+HUMMEL is a filtration specialist founded in Germany in 1941, now operating globally with around 23,000 employees. The company says much of its experience comes from the automotive sector, but the same know-how has increasingly been transferred to rail.
9:35 Tim Biegel of MANN+HUMMEL then starts the main presentation, looking at how fuel filtration requirements are changing. He says modern engines need much finer filtration than in the past, while operators are also asking for smaller, more modular and more sustainable systems.
He first explains the standard two-filter layout used in many diesel rail vehicles. A pre-filter is mainly used to separate water from the fuel, while a second high-efficiency main filter protects the common-rail injection system from fine particles. MANN+HUMMEL is also developing a one-filter concept, where water separation and fine particle filtration are combined in a single unit. According to Biegel, the main advantage is simpler packaging and less space needed onboard.
Biegel then moves to biodiesel, which he says creates new challenges for filtration. The problem is that biodiesel can behave very differently depending on what it is made from, how it is produced, how it is stored and what kind of conventional diesel it is blended with.
One of the biggest issues is water. Biegel says some biofuels can hold five to ten times more water than conventional diesel, which makes water separation much more important. Biodiesel can also lead to higher particle contamination, faster fuel degradation and shorter filter service intervals. Some fuels can affect seals and other elastomer parts as well, causing them to swell or shrink depending on the fuel type.
9:45 Another issue is microbial growth. Bacteria and fungi can form in biodiesel, especially during storage, and eventually clog the filter. MANN+HUMMEL is working on a bio-functional coating for filter media. The idea is to reduce bacterial and fungal growth directly in the filter and help extend service intervals.
Biegel says better filtration can solve part of the problem, but not everything. The actual filter lifetime still depends heavily on the quality of the fuel used in operation. For example, whether a filter lasts 500 or 1,000 hours cannot be decided from the filter design alone. Operators still need to monitor real fuel quality and analyse used filters.
He also notes that biocides can initially increase contamination after treatment, because dead microorganisms then have to be caught by the filter.
9:50 Biegel then presents MANN+HUMMEL’s rail filter range, including traditional spin-on filters, newer WaveLOCK and cartridge systems, and customised modules. The cartridge design is meant to reduce waste. Instead of replacing the complete metal housing during maintenance, only the internal filter element is changed.
He also points to EN 45545-2 fire and smoke certification for railway use, and then looks at one-stage and three-stage water separation. In the three-stage design, the first layer filters particles, the second helps small water droplets combine into larger ones, and the third separates the remaining water before it reaches the engine.
Biegel then takes a closer look at water separation, especially important when trains run on biodiesel. He compares MANN+HUMMEL’s one-stage and three-stage designs. In the simpler version, the filter medium itself repels water. Fuel passes through it, while water stays on the outside of the filter, forms larger droplets and eventually falls into the collection chamber.
As more dirt collects on the medium, its ability to separate water gradually falls. The three-stage system deals with this differently. The first layer handles particle filtration, the second brings small water droplets together, and the last barrier stops the remaining water before the fuel leaves the filter. Biegel says this keeps water separation much more stable over the full service interval, which is why MANN+HUMMEL recommends this setup for biodiesel.
10:05 MANN+HUMMEL uses cellulose, synthetic and glass-fibre media, as well as combinations of them, depending on how fine the filtration needs to be. For the most demanding applications, the company is moving towards what it describes as near-absolute filtration. One of its high-performance media, for example, is designed so that out of around 10,000 particles measuring 4 micrometres, only one passes through.
But efficiency is only one part of the job. Filters also have to hold enough dirt to last through the required maintenance interval. Biegel says MANN+HUMMEL is working on increasing the dirt-holding capacity of its existing media, particularly as newer fuels can bring higher contamination levels. He explains that development starts with computer modelling of different filter structures before physical samples are produced. These are then tested for filtration efficiency and service life.
MANN+HUMMEL also examines used filter samples in detail to see where exactly particles collect inside the different layers. Among the methods mentioned are microscopic media analysis and nano-CT scans. The idea is to understand how the filter loads up in real use and then adjust the next design accordingly.
10:15 The webinar ends with a short Q&A and frequently asked questions section, returning to the practical issue of what happens when operators increase the share of biodiesel or other renewable fuels.
Biegel says the first thing operators may notice is a shorter filter service interval, mainly because some fuels bring higher particle contamination. The answer is that the filter needs enough dirt-holding capacity to cope with the extra load over time.
Water remains the other major point. Because biofuels can contain considerably more dissolved water than conventional diesel, Biegel again recommends using a three-stage water separation system when moving to higher biodiesel blends.
Asked what MANN+HUMMEL has seen in practice from operators already using high biodiesel blends or HVO, he says there is no single service-life figure that works everywhere. Much depends on fuel quality, storage conditions and biological contamination. A well-managed fuel supply may create relatively few problems, while poor storage or microbial growth can quickly load the filter and shorten its life. This is why MANN+HUMMEL still relies heavily on feedback from operators and analysis of filters taken out of service.
The company says its current fuel-filter portfolio is compatible with biodiesel and HVO, but Biegel advises operators not to assume that an existing installation can simply switch fuels without checking it first.
If a fleet is moving from conventional diesel to a higher biodiesel blend, he recommends reviewing the existing filter design and, in particular, the materials used for seals and other components. Different fuels can affect these materials differently, and the wrong combination can eventually lead to leakage.
This concludes the 'Railway Fuel Filtration for Internal Combustion Engines' webinar. Thank you for tuning in with RAILTARGET for the updates.