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BioDiesel Class 101

Class # 9 - Filtering

    Even though your BioDiesel may look nice & clean, it needs to be filtered before placing into your vehicle. Most older diesel engines will not tolerate particulates larger than 10 microns & the newer diesel engines will not tolerate particulates larger than 2 microns. For size reference, a fine blonde human hair is around 60 microns wide so at 10 to 2 microns you can see we are speaking of very small particles that are invisible to the human eye.

    Any moisture or water in your fuel can quickly kill fuel injection components in short order. Quality diesel fuel filters incorporate a media called water block which work well with #2 diesel fuel because that fuel will not mix with water. When dealing with BioDiesel though these filters are ineffective because if it contains contaminates, BioDiesel can absorb or mix with water. If the water is dissolved in the BioDiesel it can pass through a water block filter. If you did a sufficient wash, this is not usually a problem because the soap & alcohol have been reduced to a point that the BioDiesel can't hold much moisture. If you did not wash your fuel it will hold moisture which can be absorbed out of the air & this can condense into water droplets inside of your fuel tank when the fuel cools down below the dew point temperature at which the fuel sat at when it absorbed the moisture. Because the water was dissolved in the fuel it will not be blocked by a water block filter. After cooling down below the dew point it will condensed out water. Since this water is no longer dissolved & now free it can wreak havoc in your fuel system corroding injectors & causing starvation of lubrication to injection system components. Since water block filters are not always effective with BioDiesel, always insure your fuel is completely washed & totally bone dry before filtering & storing it.

    Composition of particles in your fuel is important & your newly made BioDiesel will have carbon & iron particles in it (from the pipes & steel tank) along with fine sand or dirt that got blown into it. This is normal All fuel has these tiny particles and they need to be filtered out. Particles cause accelerated wear on your Fuel System Injection Components which is why all fuel needs to be filtered. Do not think that BioDiesel is alone in this particle issue because #2 diesel fuel commonly becomes contaminated along the way after it exits the refinery. Storage tanks, connecting pipes, valves, tanker trucks, the tanks at your local filling station, everywhere along the way dirt, grit, steel, iron, carbon particles all migrate into the once rather clean fuel. Some diesel fueling stations have filters on the pump which gives people a false sense of security. A lot of fueling station owners find that replacement filters are costly and poke holes in them so they do not need to replace the expensive filters & increase profit margins at your expense.

    Fortunately for us filtering of BioDiesel is rather cheap & easy to do. Our book gives many excellent suggestions on filtering, we even have instruction on how to build a low cost low pressurized filtering tank in the book, don't miss out buy the PGB book now

    Always use a constant pressure to filter your fuel. Beware of pressures placed on the inlet side of the fuel filter! Most filters are designed to be placed on the Vacuum side of a pumping system which limits the differential pressure that can be placed across them, they simply are not designed to be placed on the pressure side where pressures can soar to well beyond design limits. Most automotive filters contain a Bypass valve which is designed to allow liquid to flow around the filter media if the filter gets clogged or design pressures are exceeded. By design, the filter media bypass valve opens during media over pressurization and  not only prevents the media from bursting it also prevents lubrication starvation of system components down stream. After all dirty fuel or oil is better than no oil as a lubricant.

    As you can imagine, bypassing the filter media does not clean the liquid! Because of this problem we strongly suggest you get our book because most other filter designs use pumps to move the liquid through filters which do not limit the pressure across the filter. This causes high differential pressures to develop as the filters clogged up over time & eventually open the Bypass valve or worse, the pressure is exceeded from day one & the filter media has always been bypassed! You would never know this occurred & your BioDiesel would go out as dirty as it went in or perhaps more so since it may have picked up more particulates from your filter systems pump & plumbing!

    Particles in the 2 to 20 micron range are the ones we are most concerned about and are well below the threshold of human vision so you would never know the difference. As an example, a blonde human hair is about 60 microns thick. Conclusion... Why chance risking your expensive Injection Pump & Injectors get the PGB book now? By the way, Injection Pumps & Fuel Injectors are not user replaceable parts in most diesel engines, you must have a mechanic put in the pump or injectors for BIG Money on top of the cost of the pump or injectors! Price yours injection parts & see if you want to risk having an open Bypass valve and dirty fuel !

    Yes, you can gravity feed your BioDiesel through a filter but this is slow & tedious. Liquids seek there own level, so you can not flow to a higher elevation such as into a storage tank or drum sitting next to the gravity filter. Our Filter tank design eliminates these problems get our PGB book and build a really great filter tank to solve your filter problems !

    Not sold yet? Our filter tank design limits the amount of differential pressure on the filter media which is user adjustable and provides for a constant low pressure with reasonable flow volume. We recommend only using enough pressure to get a reasonable flow with a new filter. When using our design, the pressure can never go any higher than what you set, as flow decreases over time you will know the filter is clogging up, once the flow declines to what is unacceptable to you, you simply replace the filter without ever having to worry if a Bypass valve was activated! Be safe, buy our PGB book & build our low constant pressure filter tank! Besides, with our design you can move your filtered fuel up hill.

And you thought we forgot.....

  1. What happens if you use more pressure than a filter is designed for?

  2. When using our Filter Tank design, how do you tell if the filter media is plugging up?

  3. What are the contaminate particles in #2 diesel fuel made of?

  4. What do some commercial fuel stations do to the final filter to save money?

  5. Why is the Filter tank design in our PGB book superior to other filter systems?

  6. Do you want a high or low differential pressure across a fuel filter?

  7. What does grit do inside an Injector Pump?

  8. Newer diesel engine designs will not tolerate fuel system particles larger than how many microns?

  9. How many microns thick is a human hair?

  10. Do water block filters always work to keep out water?

  11. Can you see a 10 micron or smaller particle?


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Last modified: 11/26/16