Fuel filtration for diesels

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  • Air enters all diesel systems and most of that time the air that comes in bring moisture with it. Air and moisture are the enemies of any fuel system—whether that system is petrodiesel or biodiesel. The presence of air will increase oxidation of the fuel over time. The best thing to do to minimize oxidation is to have good turn over of the fuel and not to store if for long periods of time. Most fueling systems do this as part of normal business, so it doesn’t end up being a problem. If there are systems where the fuel might stay around, fuel stabilizers are recommended as are desiccant dryers on the air vents which will minimize the potential for moisture contamination.
  • Micro-organisms have been found in diesel fuel forever, and seem to be an increasing issue since the advent of ultra low sulfur diesel fuel. They grow at the water interface at the bottom of the tank, living in the water but feeding off of the fuel—whether that is petrodiesel or biodiesel or a biodiesel blend. If micro-organisms are present in a high enough quantity they can clog a fuel filter. They are relatively easily treated with a variety of conventional biocides which kill the organisms which can then be filtered out. Keeping the water out of tanks on a regular basis can go a long way toward reducing or eliminating micro-organisms. Filters with microbial growth appear black and slimy and typically have an odor different that is normal. There are a variety of microbial testing kits that users can buy to see if their fuel is starting to grow bugs. Its not desirable to regularly treat for bugs unless you actually have them, since you don’t want the bugs to develop a resistance to the biocide.
  • The issue of water contamination is one that is poorly understood with biodiesel and biodiesel blends. This is primarily because of the issues with ethanol being water loving and people just automatically believe the same issues with ethanol exist with biodiesel. Pure biodiesel, B100, can hold slightly more water than diesel fuel—about 1200 ppm vs. 300 ppm) but even that is still a very, very small amount of water (0.12%) and is virtually the same as the amount of water gasoline holds (about 0.1%). In fact, biodiesel processors use the fact that water settles out of biodiesel, as many utilize a water wash step to helps to remove soaps and catalyst from B100. Data from NREL shows that B20 blends have similar water saturation characteristics as does petrodiesel alone. Both petrodiesel and B20 (or lower blends) hold somewhere between 100 and 300 ppm of water, with any more than that settling to the bottom of the tank. Keeping water out of tanks is always a good idea, and a good preventative maintenance program of checking tanks for water and if found removing that water is always a good idea for both petrodiesel and biodiesel.
  • Here are some examples of filters that had high water content.
  • Reading of the bullets is sufficient here.
  • Reading of the bullets is sufficient here.
  • Reading of the slides is sufficient here.
  • Reading the slides is sufficient here.
  • Reading the slides is sufficient here.
  • You can use this handy checklist in the shop if you have filters coming in from the field and the user thinks it is a biodiesel problem. More than likely its not a biodiesel problem!
  • Fuel filtration for diesels

    1. 1. Fuel Filtration for Modern Diesel Fuels National Biodiesel Board Technician Outreach Program
    2. 2. Today’s Topics <ul><li>Changes in modern diesel fuel </li></ul><ul><li>Basics of diesel engine fuel filtration </li></ul><ul><li>Fuel Filter design </li></ul><ul><li>Fuel Filter media </li></ul><ul><li>Fuel quality </li></ul><ul><li>Filter efficiency </li></ul><ul><li>Resources </li></ul>
    3. 3. Changes in modern diesel fuel <ul><li>Emissions & air quality driven </li></ul><ul><li>Ultra Low sulfur Diesel </li></ul><ul><li>Low Sulfur Diesel fuel, Off-road </li></ul><ul><li>Biodiesel & Biodiesel Blends </li></ul><ul><li>Non- Biodiesel fuels </li></ul><ul><ul><li>Coal Slurries </li></ul></ul><ul><ul><li>Raw Vegetable Oils and Fats </li></ul></ul><ul><ul><li>Non-Esterified Oils </li></ul></ul><ul><ul><li>Partially Esterified Oils </li></ul></ul><ul><ul><li>Blends With Diesel </li></ul></ul><ul><ul><li>Non Ester Renewable Diesel </li></ul></ul>
    4. 4. Diesel fuel and its injection Common Rail Diesel and Unit injection fuel injectors operate at high pressures They are electronically controlled for optimum fuel metering and complete combustion End goal is cleaner diesel emissions
    5. 5. Fuel Filter Variation <ul><li>Capacity is the measurement (in grams) of the total amount of containment a filter can retain at a rated flow and given end-point (restriction). </li></ul><ul><li>Restriction is the pressure drop across the element at a given flow, temperature, and fluid viscosity. </li></ul><ul><li>The type of media and general filter construction defines restriction. </li></ul>
    6. 6. Fuel Filter Efficiency <ul><li>Efficiency is the ability of the filter to remove particulate (% efficient) at a given micron (size) </li></ul><ul><li>The type of media being used ultimately defines the filter's efficiency. </li></ul>
    7. 7. Filter Micron Rating <ul><li>What is a micron? </li></ul><ul><li>The common unit of measurement in the filtration industry is the micron or micrometer. </li></ul><ul><li>One micron equals forty millionths of an inch (.00004). </li></ul><ul><li>A single human hair is approximately 70 micrometers. </li></ul>
    8. 8. Fuel Filter Media <ul><li>Silicone Treated Cellulose </li></ul><ul><li>Glass and Cellulose Co-Pleated </li></ul><ul><li>Cellulose and Meltblown Combination </li></ul><ul><li>The type of media and the amount (square inches) of media defines capacity. </li></ul>
    9. 9. Primary Fuel Filter <ul><li>Provides low restriction because it is mounted on the suction side of the fuel pump where normally a suction pressure of only 5-6 pounds per square inch is available. </li></ul><ul><li>The primary filter protecting the transfer pump and lightening the load of the secondary fuel filter (if installed). </li></ul><ul><li>Primary fuel filters typically have a nominal rating of 10 - 30 microns. </li></ul><ul><li>Not all vehicles have a primary filter </li></ul>
    10. 10. Secondary Fuel Filter <ul><li>The secondary fuel filter is designed to offer full protection to the fuel injectors. </li></ul><ul><li>It is mounted between the transfer pump and the injectors. </li></ul><ul><li>Secondary filters tend to see much higher pressures than primary filters. </li></ul><ul><li>Secondary fuel filters typically have a nominal rating of 2 - 10 microns. </li></ul>
    11. 11. Water Separators <ul><li>Water flowing at high velocity between highly polished valve seats and through fine nozzle orifices causes a wearing action that approaches that of abrasion. </li></ul><ul><li>The presence of water, especially with entrained air and various fuel components, causes rust and other chemical corrosion that eats away at the finely mated surfaces. </li></ul><ul><li>Use chemically treated paper to repel water which then settles by gravity to the bottom of the filter. </li></ul><ul><li>Accumulated water can be drained from the filter if equipped with a drain valve or plug. </li></ul>
    12. 12. Water Separators <ul><li>Emulsified water is a problem for both ULSD and biodiesel </li></ul><ul><li>Traditional media is challenged by both fuels </li></ul><ul><li>Interfacial Tension </li></ul><ul><li>Fuel Surfactancy </li></ul><ul><li>Fuel/Water emulsion stability </li></ul>
    13. 13. Fuel Quality concerns <ul><li>Out of specification fuel of any kind can clog filters and damage internal components </li></ul><ul><li>Purchase fuel that has been properly filtered to meet your vehicle’s needs </li></ul>
    14. 14. Asphaltenes <ul><li>Asphaltene is a by-product of fuel as it oxidizes. </li></ul><ul><li>These particles are generally thought to be in the half micron - 2-micron range </li></ul><ul><li>Thought to be harmless to the injection system, as they are soft and deformable. </li></ul><ul><li>As these tiny particles pass through the filter media they tend to stick to the individual fibers. </li></ul><ul><li>Aphaltenes can be observed in normal fuel filters as a black, tarry substance on the dirty side of the element </li></ul>
    15. 15. Fuel Filter Maintenance <ul><li>Adhere to manufacturers recommended maintenance </li></ul><ul><li>Examine internal filter media </li></ul><ul><li>How full is the filter? </li></ul>
    16. 16. Exposure to Air <ul><li>Enters through vent pipes and contains large amounts of moisture. </li></ul><ul><li>Generally displaces the fuel as tank is emptied. </li></ul><ul><li>It is not practical to keep air from entering the tank. </li></ul><ul><li>Will increase the oxidation of fuel. </li></ul><ul><li>Do not store fuels for long periods of time in partially empty tanks without stabilizers. </li></ul><ul><li>Consider desiccant dryers. </li></ul>
    17. 17. Microbial Growth <ul><li>Microbes are bacteria or fungus that live and propagate in fuel at the fuel/water interface. </li></ul><ul><li>Water needed to live—no water, no bugs. </li></ul><ul><li>Hydrocarbons in petrodiesel or biodiesel provide the food and the water provides the oxygen. </li></ul><ul><li>This environment is needed for living, growth, and reproduction. </li></ul><ul><li>The filters with microbial contamination often had an odor different from the normal fuel smell. </li></ul>
    18. 18. Water Contamination <ul><li>ULSD reaches water saturation at approximately 200-300 ppm. More settles to the bottom. </li></ul><ul><li>NREL B20 survey data: same water saturation level as petrodiesel. More settle to the bottom </li></ul><ul><li>B100 can hold more water, up to 1200 ppm </li></ul><ul><ul><li>Still very small—0.12%, on the same order as gasoline can hold water. Un-dissolved water settles to the bottom like it does in petrodiesel tanks. </li></ul></ul><ul><ul><li>While higher than petrodiesel, biodiesel is not water loving (i.e. hygroscopic) like ethanol is. Most people do not understand this fact. </li></ul></ul>
    19. 19. What could I see in a Diesel Fuel Filter? Severe water saturation High Water Concentration
    20. 20. Icing of the filter <ul><li>When there is excess free water in fuel, it can form ice on the filter and cause filter plugging in cold temps. A filter which has been plugged but is clean and new at room temperature indicates that icing is the likely cause. </li></ul><ul><li>Since the temperatures of engines are warm, any moisture picked up within the engine can be brought back to the fuel lines. This moisture can freeze overnight in low ambient temperatures. </li></ul>Free water
    21. 21. What could I see in a Diesel Fuel Filter? <ul><li>Some of the filters had solid sediment within the folds and solid particles in the filter casing. </li></ul><ul><li>Sediment present in the fuel or rust particles from within the engine can collect over time and plug the filter even when there are not necessarily problems with the fuel. </li></ul><ul><li>Not always related to biodiesel use </li></ul>This filter had a rust sediment plugging issue, this substance came back at 99.5% iron
    22. 22. <ul><li>High level of paraffin material could be from the way ULSD is processed. </li></ul><ul><li>When the temperature of the fuel is at or below its cloud point, paraffin material will precipitate out and collect on the bottom of the tank. </li></ul><ul><li>When warmed to room temperature the paraffin wax will turn back into liquid. </li></ul><ul><li>Paraffin build-up does not come from biodiesel fuel. </li></ul>What else could I see in a Diesel Fuel Filter?
    23. 23. What could I see in a Diesel Fuel Filter? Glycerin from off specification biodiesel Other contaminants like water and sediment
    24. 24. Oxidation <ul><li>Filters with a black and shiny surface but no microbial growth odor or gel or sediment indicate they may be plugged by oxidation build-up. </li></ul><ul><li>Because many newer engines run at higher temperatures, there may be a black “asphaltene” petrodiesel type material collecting on the filter. </li></ul><ul><li>This phenomenon has been seen all around the country, often in newer engines. </li></ul>
    25. 25. Oxidation <ul><li>Petrodiesel does not have an oxidation specification, while B100 and B6 to B20 specs already do. </li></ul><ul><li>Biodiesel can also oxidize, but oxidized biodiesel manifests itself in acid numbers which are out of spec </li></ul><ul><li>The acid number for biodiesel will go out of spec before filter clogging occurs </li></ul>
    26. 26. Troubleshooting Checklist <ul><li>Fuel Storage Tank Maintenance – Reduce exposure to air, water, and microbial growth </li></ul><ul><li>Fuel/Water Separators – Excess water in tank can cause icing in filters </li></ul><ul><li>Oxidation – Hot fuel return to fuel tank, aged diesel fuel </li></ul><ul><li>Paraffin Wax – Temperature at or below cloud point </li></ul><ul><li>Recommend regular fuel filter maintenance </li></ul>
    27. 27. Filtration Resources <ul><li>www.biodiesel.org </li></ul><ul><ul><li>Technical Library </li></ul></ul><ul><ul><li>Biodiesel Bulletin </li></ul></ul><ul><ul><li>Educational Videos Available </li></ul></ul><ul><ul><li>Informational Resources </li></ul></ul><ul><ul><li>Technical Resources </li></ul></ul><ul><ul><li>On-line Database & Spec Sheets </li></ul></ul><ul><li>Southwest Research International Filtration Conference </li></ul><ul><li>Filter Manufacturers Council http://www.filtercouncil.org/ </li></ul><ul><li>Donaldson Filtration </li></ul><ul><li>Society for Automotive Engineers </li></ul>

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