Part 2 Of The Bioblend Problem And Solution:Just to step back for a moment and summarize where we left off... In my earlier posts we saw that the raw materials to be used as blend stock, bio ester vs petroleum based, the petroleum based diesel was far superior for low water content, as much as 15 times lower for saturated water. So with the soybean based esters there is more water, and what is problematic is its affinity to absorb more water. The problem is compounded in that the surfactants involved tend to emulsify the water and by their chemical nature cling to the surface of the minute water droplets and keep them dispersed.
Unlike petroleum based diesel fuel which tends to agglomerate the water into large droplets that end up at the bottom of the prefilter bowl, the blended fuels no longer have that property.
Some of the bioblend water will cling to the filter face, some will escape through the filter to the fuel rail, and as the filter media absorbs or holds some of the water there is no longer that surface available so you are continually diminishing the ability of the prefilter which may start at 70% efficiency for small water droplet removal, it is being constantly diminishes dictated by the water levels in the fuel.
So we can no longer control the water level in the fuel and we can no longer effectively filter it out. That is where most of the current fuel primary filter technology is today. You have excellent fuel filtration for particles today, George brought up Nanonet but this is secondary filter technology, mostly aimed at particle wear issues. Cat makes one of the finest fuel secondary filters on the market, best beta and particle capture rates all the way down to 2 microns. I am a big fan of this filter and Dave I am sure is also. We really do not have a secondary filter problem, they do the job very well today. The primary filter has the job of extracting the water, and removing large particles to protect the flow rates of the secondary filter. High capture rates of 30 or10 micron media is where the primary filter design has operated. It is really too bad that that Cat does not focus research on primary filtration design which for the most part is left up to the OEM vehicle designer to choose, like Beaver did.
The net of all this we need a filter that is specifically designed to extract the emulsified small droplets of surfactants combined with water that has enough capacity to handle the vastly increased water load in the fuel.
Some good info from Filtramax:This is the most misunderstood area of diesel filtration. There are a variety of technologies of water removal filtration systems:
Polymer: Most “water filters” are polymer based water-blocks. Polymer is used in diapers. The polymer powder turns to a solid gel mass when water is introduced to the element. The filter is now into bypass offering no further protection. If you have a large amount of water, you will require cases of these elements. (waste of time and money)
Absorption: The second most common removal media is absorption elements. These elements are effective at capturing and storing water in the media – measured in pounds or gallons of water removal. The elements must be disposed of and replaced with new filter media as they reach their limit.
Coalescing: The best water removal technology is to coalesce the very fine water droplets (some as small as .2 µm) on the fibers of the media. The media is hydrophilic and holds on to the small droplets until these droplets begin to meet each other on the fibers to form larger droplets. The larger droplets then fall to the bottom of the filter housing and can be automatically or manually drained away. The media is long lasting – up to 4 years – if protected upstream from particulate.
Diesel Pest: Diesel fuel tanks can become contaminated with micro-organisms (bacteria, yeasts, fungi and algae) every time the tank is filled or ventilated.
Micro-organisms can only survive, grow and multiply in the water phase of any medium. Water phases develop during storage and transport, particularly when damp air inside the tank condensates.
Microbiological contamination can have very serious consequences, resulting in a loss of diesel quality. The by-products of micro-organic metabolism block filter elements, water separators and injection pumps. The material of the tank walls and pipes can also be severely damaged. Corrosion is further accelerated by water-soluble salts and hydrogen sulphide, a by-product of metabolism.
Water concentration is the decisive factor for microorganism growth, and accordingly any strategy aimed at combating diesel pest must start by reducing the amount of water in the fuel. This can be achieved by implementing continuous fuel and oil treatment to prevent the water content from rising above 60 ppm.
Ed back... I noted in my mind that 60PPM water concentration is probably a pipe dream but what is clear is that the tanks more than ever should be kept full. Over the road truckers that keep pushing fuel through the system will not absorb into a tank what an RVer would. If you can store your RV without bioblend or a low level bioblend, B5 or less, that would be great. One exception may be the desert southwest, given the very low humidity.
So where we need to go is to install a coalescing filter. The process of removing water has gotten more complex and you need a more complex filter designed specifically to handle this problem. Dave has mentioned filters gelling up and plugging and my guess is that is water and surfactant consuming the available filter media.
The coalescing filter process is basically a filter within a filter that all the fuel must pass through. The first filter is designed to break the emulsion by striping the surfactants from the water droplet and letting it pass on to the inner filter. Now the water is in a tiny droplet form that wants to cling to the surface of the extensive fiber network of the second filter that is designed to form large enough water droplets to accumulate and drop into the base of the filter. The filter capacity is maintained because the filtering process is designed to shed the water....self renewing if you will.
The OEM manufacturers have been worried about warranty claims and are keenly aware of the problem. This is an example of a coalescing filter for a Duramax engine that now comes standard, other OEMs are on the same page.
http://www.catching.com/wp-content/uploads/2014/08/7717_Rev_A_PFF50216_GM_Duramax_Diesel_Fuel-Filter.pdfIn that attachment you will notice that the water removal efficiency is rated at 99% efficiency and notes it is for all blends and types of diesel fuel. No other filter type makes any claim close to 99%. Parker Racor is the leading supplier of this technology at the moment but others are sure to follow. I will do a short segment next on where they are with making a coalescing primary filter available that is suitable for our RVs and what could be done now with today's technology.
As far as sending some additive through the system to strip what is there on a filter face, I am wary about sending what was not intended through the fuel rail. I wish the manufacturers like Cat and Cummins would do some real world testing and weigh in on these things with real measurements of what is happening to the fuel make up going out of the filter to the engine when you use one of these products. Data unlocks what is unknown and lets you understand how and if these products work without causing damage. I am not saying it is bad, I just do not know, but am wary...Hope this helps.
Later Ed