and .. Why Do I Need Clean Diesel ?
( given the number of recent posts regarding failed injectors
( this info. posted for reference ..
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
the following text taken from:
http://www.mycleandiesel.com/pages/Problems.aspx
to see the pics described in the text .. visit the link
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Clean diesel is necessary for the proper function of modern equipment. Without it, you risk increased downtime and inflated maintenance costs. This is especially true with newer equipment, which requires extremely clean fuel to prevent damaging high pressure common rail engines. Additional fuel quality challenges have arisen due to recent changes to diesel chemistry itself, further increasing the need for efficient filtration.
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Hard Particulates Damage Engines
( HPCR .. High Pressure Common Rail )
Dirty fuel will cause premature parts failure in equipment of any age. Because of the extremely high pressures, this damage is even more pronounced in newer equipment with HPCR fuel systems. Hard particulate is commonly referred to as "dirt", but is in fact made up of a wide variety of materials found at job sites (coal, iron, salt, etc.), generated by fuel tanks and lines (rust, corrosion, etc.) and inside engines (carbonatious materials and wear particles).
DAMAGE CAUSED BY HARD PARTICULATE
Hard particulate causes problems with moving parts in the fuel system. This can lead to starting problems, poor engine performance, idling issues and potentially complete engine failure.
The spray pattern generated by the HPCR injector is critical for proper combustion and overall fuel system performance. It must be extremely precise in terms of quantity, distribution and timing. Ball seat valves are sealed with balls that are only 1mm in diameter. A good seal is absolutely necessary for proper injection. Damage from erosive wear, will cause over fueling, leading to decreased fuel efficiency and eventually shut you down altogether.
Pump performance can also be compromised by scoring and abrasive wear. These issues are magnified by the tighter tolerances and extreme pressures in HPCR engines. In these circumstances, it is the smallest particles (1-5 microns in size)
that cause the most damage, virtually sand blasting part surfaces.
ALLOWABLE LEVELS OF HARD PARTICULATE
In some parts of the world, 10,000 gallons (38,000 liters) of “typical” diesel contains 1-1/2 lbs (700 grams) of hard particulate; this is 1000 times more than the 1/4 oz. (0.7 grams) per 10,000 gallons (38,000 liters) that is allowed by the cleanliness requirements of high pressure common rail fuel systems. In reality, there is no "OK" level of hard particulate. Injector manufacturers are very clear that damage caused by hard particulate reaching the engine is not a factory defect, but rather the result of dirty diesel that is not fit for use in HPCR fuel systems. At the end of the day, the end user is responsible for the fuel he puts into his equipment, and the consequences thereof.
HOW DOES DIRT GET INTO FUEL?
Dust and dirt are all around us, especially on job sites. Diesel fuel is fairly clean when it leaves the refinery, but becomes contaminated each time it is transferred or stored. Below you will find some of the key contributors of fuel contamination:
Pipelines: Most pipelines are not new, and certainly not in pristine condition. Corrosion inhibitors are added at most refineries to help protect pipelines, but rust and other hard particulate is nevertheless picked up by the fuel that flows though them.
Barges and rail cars: How often are they drained and scrubbed out? What was in the last load? Where did it come from? How much of it was still in the tank when your load was picked up? How long was it in transit? Is the tank hermetically sealed? There are lots of opportunities for contaminants to make their way into the fuel.
Terminal tanks: Terminal tanks usually see a high rate of turnover, so there is not much time for the fuel to pick-up contamination from outside ingress. Has the tank ever received a "bad load" from a pipeline or a barge? Has larger dirt had a chance to settle on the bottom of the tank? How often has it been cleaned out? Was it just filled? Did the bottom get churned up in the process? How full was the tank when your fuel was loaded into the delivery truck? There are many variables that can affect fuel cleanliness.
Delivery trucks: All the same issues that apply to stationary tanks also apply to tanker trucks, except that truck tanks never get a chance to settle. In addition, have you ever considered how much dirt gets into that tanker while it is delivering fuel to a customer, potentially a customer in an extremely dusty environment? As fuel flows out, air is sucked in to displace it. Is there anything protecting the inside of the tank from all the dust in the air? Generally not. Venting is typically completely unprotected.
Storage tanks: Onsite bulk storage tanks typically see less rapid turn-over than terminal tanks. In addition to those issues, yard and jobsite tanks can also develop serious problems with other sources of contamination, such as the ingress of dirt and water, condensation, rust, corrosion, microbial growth, glycerin fall-out and additive instability. Time and temperature become big factors affecting fuel quality.
Dispensing process: How far does your diesel need to travel between the bulk tank and the dispenser? The more pipe it runs though, the more potential there is for contamination. Are your dispenser nozzles kept clean? Are they ever dropped on the ground? Then what? What about the vehicles' fuel tank inlets, are they clean? Think about the extremely tight tolerances in your fuel system, then take another look at housekeeping issues. You will see them through new eyes.
Onboard fuel tanks: Contamination continues even after the fuel is in the equipment. What has that tank seen in the past? Has it been left stagnant for long periods? What kind of protection is there on the equipment's air intake vents? Heavy equipment does hard, dirty work.
Engines: Unfortunately, even if the fuel in your tank could be perfect, additional contamination is generated by the fuel system itself. Wear particles are created by mechanical friction. High heat and extreme pressure generated inside the modern engine, lead to coking and the creation of carbon products at the injector. Much of this internally produced particulate is returned to the fuel tank along with the unburned diesel.
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Water is the Enemy of Diesel Engines ( " All diesel contains some percentage of dissolved water. " )
Water has always caused rust and corrosion of fuel system components and infrastructure. Modern fuel systems are so much less tolerant than lower pressure systems, that manufacturers now specify zero free water must reach the engine.
DIRECT DAMAGE CAUSED BY WATER
Water causes damage to both fuel tanks and engine parts. Rust and corrosion in the tank create hard particulate that is passed along in the fuel, causing engine wear. Component life is also shortened by water etching, erosion, cavitation and spalling, such as:
injector
Rust: In contact with iron and steel surfaces water produces iron oxide (rust). Rust particles that get into the fuel, like other hard particulates, will cause abrasive wear to parts. Premature wear can cause part failures.
Corrosion: Corrosion is one of the most common causes of injector problems. Water combines with acids in the fuel to corrode both ferrous and non-ferrous metals. This is made worse when abrasion exposes fresh metal surfaces that readily corrode.
Abrasion: Water has lower viscosity than diesel, therefore providing less of a lubricating "cushion" between the opposing surfaces of moving parts. This leads to increased abrasive wear.
Etching: Etching is caused by water-induced fuel degradation which produces hydrogen sulfide and sulfuric acid that "eat" metal surfaces.
Pitting and Cavitation: Pitting is caused by free water flashing on hot metal surfaces. Cavitation is caused by vapor bubbles rapidly contracting (imploding) when exposed to sudden high pressure, which causes them to condense back into a liquid. These water droplets impact a small area with great force, causing surface fatigue and erosion.
Spalling: Occurs due to hydrogen embrittlement and pressure. Water is forced into microscopic cracks in metal surfaces. Then, under extreme pressure, it decomposes and releases hydrogen in a “mini-explosion” which enlarges the cracks and creates wear particles.
Ice: Free water in fuel can freeze, creating ice crystals that behave just like any other hard particulate. They can create wear in fuel systems and (in large volumes) clog fuel filters. A fuel filter's job is to protect the engine by stopping hard particulate. Engines and filters do not differentiate between dirt and ice. Damage caused by ice can be hard to correctly diagnose since the ice will melt and disappear long before a lab examination can occur.
INDIRECT DAMAGE CAUSED BY WATER
Water also contributes to or aggravates a number of additional issues, like the following:
Soft Solids: Water is polar. Certain chemicals in additives are polar. Hydrocarbons are non-polar. This means that water and polar chemicals are attracted to each other. In the presence of free water, the chemical molecules will sometimes disassociate themselves from the hydrocarbon chain of the additive and combine with water molecules to form a new substance. The new material is a soft solid that precipitates out of the fuel and can rapidly clog filters or create engine deposits.
Microbial Growth: Like most living organisms, bacteria and fungi (molds) need both food and water to survive. If free water is present microbial growth can proliferate, creating slimes that foul your fuel and acids that corrode your tank and fuel system.
Fuel Oxidation: Free water accelerates the oxidation process and encourages the formation of acids, gums and sediments known generally as fuel degradation products.
FORMS OF WATER IN DIESEL
saturated
All diesel contains some percentage of dissolved water. The water molecules remain part of the fuel until there are too many of them. The point at which the fuel can hold no more water is called the saturation point. The quantity of water in fuel is measured in ppm (parts per million). As long as the water stays below the saturation point as dissolved water it is typically not too much of an issue. Significant problems start when water separates from diesel and becomes free or emulsified water. Emulsified water is another form of free water; the droplets are simply so small as so well mixed into the fuel that they remain suspended rather than dropping to the bottom. There are no "droplets" when water is fully dissolved in fuel.
HOW DOES WATER GET INTO FUEL?
Water can come from a wide variety of sources, some of which can be extremely difficult to control.
On delivery from supplier
Free water fall-out (beyond saturation point)
Condensation in tank
Leakage into tank (rain, pressure washing, ground water...)
Ingress from atmosphere (humidity)
Human error (unprotected vents, fill ports, seals...)
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DIESEL ADDITIVES CAN STILL HARM ENGINES
Instability Can Create Solids in Fuel
sludge
Much of the world is required to use Ultra Low Sulfur diesel (ULSD).
With the removal of sulfur, fuel properties change radically, requiring the increased use of additive in order to meet specifications. In the
real world, maintaining these fuel properties can be a challenge. Diesel is tested at many points along the distribution channel, from refinery
to terminal to distributor to end user. Chemical additives are used to correct or enhance the fuel at each of these locations.
ADDITIVE DROP-OUT
Chemically speaking most additives are very similar to diesel itself (i.e. long chain hydrocarbons) so that they dissolve into the fuel. Additives are composed of a long hydrocarbon "tail" at the "head" of which there is another element, the one intended to have a beneficial effect on the diesel. This head typically contains atoms of nitrogen, oxygen, and/or sulfur in addition to carbon and hydrogen. Unlike the hydrocarbon tail, the head is polar. The beneficial element is intended to stay dissolved in the fuel so that it can do its job. Since head elements are polar, they have a strong tendency to want to escape from the non-polar hydrocarbons and associate with other polar substances such as water, metal, dirt, degradation particles or asphaltenes. You might think of them as being magnetically attracted to each other.
Sometimes, usually under adverse circumstances, the polar elements manage to come out of solution and form a bond with other polar elements. When this happens, there are two consequences:
The chemical may no longer be doing the job it was intended to do.
The chemical, now bonded with another substance, drops out of solution and turns into a soft contaminant in the fuel.
This phenomenon is most frequently observed in the presence of poor fuel storage conditions and fluctuating temperatures. Water, improper blending practices, and cold temperatures are leading contributors to these problems.
IMPACT ON ENGINES AND FILTERS
When unstable additive drops out of solution, it forms soft, sticky, solids which can cause rapid filter plugging and deposit formation. Engine manufacturers have observed injector deposits caused by these soilds, which are chemically identical to the substances found in many rapidly plugged filters, especially the high efficiency filters specified by OEs to protect HPCR systems.
The image to the right is of filter media at 1000x magnification under a scanning electron microscope (SEM).
The media was cut from a high efficiency filter of the type used in high pressure common rail fuel systems. This filter clogged in under 30 minutes of use. Between the media fibers you will notice a film. This kind of soft contaminant coats media as if it were covered in plastic wrap, effectively disabling the filter.
filterThe filter to the left has been completely disabled by soft contaminant. It looks clean because it did not have the time to become loaded with dirt. Instead, you will notice a sort of sheen, as if the filter media had been coated with wax. This is not due to wax (fuel gelling), but to soft contaminants that have dropped out of solution in the fuel. The pink color is red dye from off-road diesel. Upon further analysis, these soft contaminants were found to have chemical profiles identical to certain components of common diesel additives such as corrosion inhibitors, cold flow improvers, lubricity improvers and others. One thing that is important note, the root causes of this specific chemical instability are not yet completely understood. They are under rigorous investigation by Donaldson Company and other industry leaders.
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MICROBIAL BACTERIA IN DIESEL FUEL
Microbes Eat Fuel and Multiply
microbes
Microbes are present everywhere, but without food and water they cannot multiply; diesel is food. When there is free water in the tank, the microbes
have everything they need to grow, fouling fuel and damaging tanks in the process. By some estimates, a microbial colony can consume up to 1% of
your fuel investment, while destroying the rest.
MICROBES NEED FOOD AND WATER
Microbial colonies proliferate at the interface between fuel and free water
that has settled to the bottom of the tank. This creates a “rag layer” which gives them everything they need to thrive. Warm temperatures will accelerate the growth of microbial colonies. Microbial growth can occur in any diesel fuel. Biodiesel, being made from plant and animal fats, makes especially good food for these bugs and contributes to the increased incidence of biological growth problems seen in recent years. Bugs can grow in petro diesel as well. Stagnant fuel is especially at risk.
DEGRADED FUEL BECOMES UNUSABLE
With time the microbial colony proliferates beyond control. This leads to acid formation, rust, corrosion and filter plugging. Fuel degrades to the point that
it can form a slimy sludge that is unusable as fuel.
gross stuff
This process can occur in a bulk storage tank or in a piece of equipment that is left idle for a long period of time. To the right is a classic example of what is called filter “leopard spotting”, which requires the filter to be exposed to both microbes and water. The black spots are microbial colonies. Live or dead, microbes will clog filters and damage fuel systems. It is important to eliminate bugs completely and permanently.
MICROBIAL GROWTH vs. ALGAE
Microbial colonies, sometimes incorrectly referred to as algae, are actually bacteria or fungus. Algae needs light to live and grow, there is no sunlight in a closed fuel tank so algae cannot survive
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THE DEGRADATION OF FUEL OVER TIME
Diesel Fuel Has a Shelf Life
ULSD and biodiesel both have reduced stability in storage compared to traditional high sulfur diesel. While it is true that removing sulfur improves stability, the hydro-treating process also tends to destroy naturally occurring antioxidants. As a result, some ULSD fuels may require the addition of a stabilizer to prevent the formation of peroxides that lead to soluble gums. Shelf life recommendations for petro diesel and biodiesel blends are less than a year, and sometimes as low as 2 months, depending on factors below.
CONSEQUENCES OF UNSTABLE FUEL
Oxidative instability in petro diesel or biodiesel leads to the formation of fuel degradation products. These include:
Gums: sticky varnishes that contribute to corrosion and injector deposits, causing over or under fueling
Sediments: particulate that clogs filters and causes abrasive wear to fuel pumps and injector.
Acids: cause corrosion of tanks and fuel systems, leading to hard particulate formation and premature parts failure.
Thickeners: increase fuel viscosity, leading to incomplete combustion and reduced fuel economy
Common consequences of fuel degradation include loss of power, increased fuel consumption, premature filter plugging, damaged fuel pumps / injectors and increased maintenance costs. Generally speaking, fuel degradation decreases the combustion quality of fuel. You may notice symptoms such as black smoke, harder starts and reduced engine performance.
FUEL DEGRADATION IN STORAGE
Time is the enemy of diesel fuel quality. Oxidative instability can occur slowly during long-term storage or be accelerated by warm temperatures, the presence of free water and contaminants. This degradation can lead to high acid number, high viscosity and the formation of gums and sediment (fuel degradation products). Biodiesel is especially susceptible to the effects of higher temperatures. Data sets vary, but a good rule of thumb is that the oxidation rate increases 2.2 times for every 18°F/10°C.
Example: biodiesel blend stored at various temperatures
68°F/20°C: marginally OK after 6 months
77°F/25°C: degraded after 6 months
86°F/30°C: degraded after 4 months
Water in fuel can accelerate the oxidation process, but even worse are the effects of the microbial infestations that can grow as a result of water in the tank. These bacteria and fungi literally feed off your fuel, leaving behind acids and various forms of black, sticky, slimy materials that corrode your tank and plug your fuel filters. Whatever the contributing factors fuel degradation cannot be reversed, the key to success is to prevent it before it occurs with good fuel handling practices.
FUEL DEGRADATION ON VEHICLE
Fuel degradation can occur rapidly on-engine when excess diesel is heated to extreme temperatures inside high pressure common rail systems and then returned to the fuel tank along with black carbon particles created at the injector. High thermal stability is important for diesel fuel to function effectively as a heat transfer fluid inside the HPCR fuel system. Future injector designs are expected to employ even higher pressures and temperatures than today to achieve better combustion and lower emissions.
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Filters Capture More Than Dirt
frozen pipe
Cold weather operability can be a huge problem. Equipment won't start in the morning or even if it does, it might stop suddenly in the middle of a job. These issues are usually caused by solids created in the fuel as the temperature decreases.
Engines and filters do not differentiate between particles. Hard or soft, contaminant or pure hydrocarbon, solids in fuel will cause trouble. These problems are made worse by new-age fuels, the sensitivity of modern engines and the high efficiency required of filters designed to protect them.
ICE
When the weather turns cold, free water in fuel will freeze. Ice crystals will behave like any other hard particulate, loading in filters or causing abrasive wear to fuel systems. In large quantity, ice can completely block filters or pipes, preventing fuel flow. De-icers may be able to help get you running in an emergency situation, but adding alcohol to diesel is generally discouraged. Keeping free water out of the fuel is by far the best solution, learn more by reviewing solutions for water problems.
GELLING
Like water, hydrocarbons turn solid when they reach their "freezing" point. Unlike water, however, they do not turn into ice. Instead, they turn into a thick, waxy substance that cannot flow through filters. This is what is referred to as "gelling". It is a characteristic of both petro diesel and biodiesel. Diesel fuel is not one "thing". Instead, it is a complicated mixture of thousands of potential compounds, each with different chemical and physical properties. The particular formula is determined by the refinery at time of production. Typically about 250 different chemicals are included, mainly hydrocarbons. Precise freezing temperature varies widely from one hydrocarbon to another, which directly relates to winter operability issues. “Winter diesel” contains a blend of hydrocarbons with generally lower freeze points than “summer diesel”.
In some countries there is a classification of fuel called "Arctic diesel" for extremely severe conditions down to -40°F/C and below. An easy way to think of fuel "freezing" is to compare vegetable shortening to vegetable oil. Both are essentially the same thing, but shortening is solid at room temperature whereas oil is liquid. The same is true of hydrocarbons. At a given temperature, some may be liquid while others assume the soft, waxy state which is the ”frozen” or solid phase of hydrocarbons. This is commonly referred to as gelling.
WINTER FUEL
When cold weather threatens, refineries and distributors can and do improve diesel's cold weather operability properties in several different ways. They can:
Select less waxy crude oils upstream of the refinery
Extend the refining process to eliminate waxy elements with higher melt temperatures (i.e. they freeze at lower temperatures)
Dilute fuel with #no.1-D diesel or kerosene, which has lower wax content
Treat diesel with low-temperature operability additives (cold flow improvers)
Fuel suppliers manage hydrocarbon blends at the time and place of sale but cannot control unusual weather swings or fuel that is kept in storage or transported to colder climates. DO NOT add heating oil to your fuel in an attempt to lower the cloud point. This practice is strictly forbidden by most equipment manufacturers and may void your warranty.
PREDICTING COLD WEATHER OPERABILITY
There are a number of tests intended to predict the cold weather performance of a certain fuel. Their relative merits are the subject of some debate. No independent test data regarding their usefulness has been published since the advent of HPCR fuel systems, high efficiency fuel filters, ULSD and widespread biodiesel.
Cloud Point: When diesel cools, wax crystals begin to form and a noticeable white haze (or "cloud") appears. The wax drops out of solution and starts getting caught in fuel filters and lift pumps. Actual cloud temperature varies based on fuel characteristics. Some low quality fuels may have cloud points as high as 40°F/4°C, but most good quality fuels will have a cloud point around 32°F/0°C (untreated). As a rule, cold flow improvers do little to lower cloud point. There are some cloud point depressants that can significantly lower a fuel's cloud point, but their use is generally discouraged because they can actually work against the anti-gels that are intended to keep fuel flowing. The best way to lower cloud point is through the addition of a hydrocarbon with lower wax content such as #no.1-D diesel.
Cold Filter Plugging Point CFPP: This is the temperature at which wax crystals will rapidly plug fuel filters, starving the engine of fuel, preventing it from starting or stopping it cold (usually when least convenient). Cold flow improvers can depress CFPP by several degrees. They do not actually lower waxing temperature, but rather work on the wax crystal itself. They alter the size and shape of the crystals so that the fuel flows better and passes through filter pores at lower temperatures.
* A note of caution: Most cold flow improvers do not work as well in ULSD as they did in higher sulfur fuel. Be sure that performance claims are based on test results using ULSD. If not, they are irrelevant. The common test method for measuring CFPP is ASTM D6371. It was developed in 1965 and uses rapid cooling methods to determine the temperature at which 20cc of diesel will no longer flow through a 45 micron wire mesh in 60 seconds or less. A CRC (Coordinating Research Council) study in 1981 determined that CFPP is not an accurate predictor of real world performance. It tends to over-state minimum operating temperatures (i.e. cold weather performance in the real world is not as good as the test would make it appear).
Low Temperature Flow Test LTFT: This test (ASTM D4539) is considered to be somewhat more accurate at predicting the performance of additized fuels and is frequently recommended for North American heavy duty trucks. Instead of using an unrealistic rapid cooling method, this test method allows diesel to cool slowly (1°C per hour), which is much more representative of real world conditions. In this test 200cc samples are drawn through a 17 micron mesh screen using 20 kPa vacuum. The LTFT point is determined when 90% of the sample no longer passes through the screen in 60 seconds or less. Although deemed more accurate than the CFPP test at predicting cold weather performance in North America, the LTFT uses a 17 micron mesh screen in determining acceptable flow. This is finer than the 45 micron mesh used for CFPP, but one can still reasonably question its ability to predict fuel flow through the high efficiency 2 micron filters used to protect today's HPCR engines.
Pour Point: The temperature at which diesel freezes is called its pour point. At this temperature fuel will freeze solid in lines. Pour point is irrelevant in terms of predicting cold weather operability because it is lower than cold filter plugging point. If fuel cannot pass through filters to the engine, the vehicle will not run. In the absence of other complications, gelled or cloudy diesel should clear as it warms. The wax crystals will dissolve back into solution and the fuel will once again be perfectly liquid. If the fuel does not clear when warmed, then another factor is at work in addition to cold temperatures. Most likely additional chemistry is present and a reaction has taken place creating soft solids that do not melt at normal operating temperatures.
GLYCERIN
Gelled fuel and glycerin solids are frequently confused with one another. But while gelled fuel is a natural phenomenon caused by cold alone, glycerin is an entirely different chemistry that is only present in biodiesel. Glycerin and other related substances (glycerols) are byproducts of biodiesel production and are not found in petro diesel. Regulations require the removal of virtually all these materials, but even at very low levels they can immobilize a fleet. As long as glycerin remains warm and liquid, it generally causes no immediate problems. At low temperatures, however, glycerin assumes a solid waxy state. It drops to the bottom of tanks, gets caught in fuel filters, and forms sticky, corrosive engine deposits.
Glycerin can turn solid at relatively high temperatures, sometimes as high as 55°F/13°C or above. Unlike standard gelled fuel, glycerin typically does not re-liquefy when the temperature goes back up. Once solid, glycerin tends to stay solid, even at high ambient temperatures. This container of in-spec B100 was completely liquid until it was cooled off in a refrigerator at 40°F/4°C. At that temperature, a solid lump of glycerin formed and settled to the bottom. This solid did not re-liquefy, even when it was heated well beyond normal on-equipment fuel temperature. Although the origins are somewhat different, many of the consequences of glycerin and gelling are the same. Cold weather causes soft solids to form, small quantities of which clog fuel filters and prevent fuel flow. This prevents engines from starting or stops them due to fuel starvation. In cold climates, more and more indoor garages are being built so that fleets can be parked inside over night to be sure the vehicles start in the morning.
CONSEQUENCES OF SOFT SOLIDS
cold glycerin
Soft waxy solids will rapidly disable filters, regardless of the age of a filter. Where will these solids form? If fuel is delivered cold, then solids may be pumped into your tank by the supplier. If the fuel cools off in the bulk tank, then solids can fall out at that point. If your diesel doesn't get cold until it is already in the onboard fuel tank, then that is where it might solidify. Wherever they form, soft solids will quickly clog the first filter they encounter.
The image to the right is an extreme case of a filter clogged with glycerin. Usually you will see nothing this dramatic. Instead, your filter will likely appear clean, with only a faint waxy sheen to the media or a small amount of deposit in the bottom of the filter can. Here you see images of cellulose, average efficiency filter media under a Scanning Electron Microscope.
celulouse
The first image to your left is of clean cellulose media. Notice the free,
darker, areas between the fibers.
”SEM"
The second image, to your right, is cellulose and glass media of the type used in primary onboard fuel filters. The areas between fibers have been completely clogged with glycerin. It can take only a few spoonful's of solidified glycerin or other soft solids to completely disable a fuel filter.
Onboard cellulose
The final image, to your left, is relatively low efficiency cellulose media of the type sometimes used on fuel dispensers. It also is caked over with glycerin. Nothing will flow through a filter clogged with glycerin. Luckily for the equipment owner, this soft waxy glycerin was caught and prevented from reaching the engine. The unfortunate consequence, however, was that these filters likely had very short lives.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
( given the number of recent posts regarding failed injectors
( this info. posted for reference ..
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
the following text taken from:
http://www.mycleandiesel.com/pages/Problems.aspx
to see the pics described in the text .. visit the link
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Clean diesel is necessary for the proper function of modern equipment. Without it, you risk increased downtime and inflated maintenance costs. This is especially true with newer equipment, which requires extremely clean fuel to prevent damaging high pressure common rail engines. Additional fuel quality challenges have arisen due to recent changes to diesel chemistry itself, further increasing the need for efficient filtration.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Hard Particulates Damage Engines
( HPCR .. High Pressure Common Rail )
Dirty fuel will cause premature parts failure in equipment of any age. Because of the extremely high pressures, this damage is even more pronounced in newer equipment with HPCR fuel systems. Hard particulate is commonly referred to as "dirt", but is in fact made up of a wide variety of materials found at job sites (coal, iron, salt, etc.), generated by fuel tanks and lines (rust, corrosion, etc.) and inside engines (carbonatious materials and wear particles).
DAMAGE CAUSED BY HARD PARTICULATE
Hard particulate causes problems with moving parts in the fuel system. This can lead to starting problems, poor engine performance, idling issues and potentially complete engine failure.
The spray pattern generated by the HPCR injector is critical for proper combustion and overall fuel system performance. It must be extremely precise in terms of quantity, distribution and timing. Ball seat valves are sealed with balls that are only 1mm in diameter. A good seal is absolutely necessary for proper injection. Damage from erosive wear, will cause over fueling, leading to decreased fuel efficiency and eventually shut you down altogether.
Pump performance can also be compromised by scoring and abrasive wear. These issues are magnified by the tighter tolerances and extreme pressures in HPCR engines. In these circumstances, it is the smallest particles (1-5 microns in size)
that cause the most damage, virtually sand blasting part surfaces.
ALLOWABLE LEVELS OF HARD PARTICULATE
In some parts of the world, 10,000 gallons (38,000 liters) of “typical” diesel contains 1-1/2 lbs (700 grams) of hard particulate; this is 1000 times more than the 1/4 oz. (0.7 grams) per 10,000 gallons (38,000 liters) that is allowed by the cleanliness requirements of high pressure common rail fuel systems. In reality, there is no "OK" level of hard particulate. Injector manufacturers are very clear that damage caused by hard particulate reaching the engine is not a factory defect, but rather the result of dirty diesel that is not fit for use in HPCR fuel systems. At the end of the day, the end user is responsible for the fuel he puts into his equipment, and the consequences thereof.
HOW DOES DIRT GET INTO FUEL?
Dust and dirt are all around us, especially on job sites. Diesel fuel is fairly clean when it leaves the refinery, but becomes contaminated each time it is transferred or stored. Below you will find some of the key contributors of fuel contamination:
Pipelines: Most pipelines are not new, and certainly not in pristine condition. Corrosion inhibitors are added at most refineries to help protect pipelines, but rust and other hard particulate is nevertheless picked up by the fuel that flows though them.
Barges and rail cars: How often are they drained and scrubbed out? What was in the last load? Where did it come from? How much of it was still in the tank when your load was picked up? How long was it in transit? Is the tank hermetically sealed? There are lots of opportunities for contaminants to make their way into the fuel.
Terminal tanks: Terminal tanks usually see a high rate of turnover, so there is not much time for the fuel to pick-up contamination from outside ingress. Has the tank ever received a "bad load" from a pipeline or a barge? Has larger dirt had a chance to settle on the bottom of the tank? How often has it been cleaned out? Was it just filled? Did the bottom get churned up in the process? How full was the tank when your fuel was loaded into the delivery truck? There are many variables that can affect fuel cleanliness.
Delivery trucks: All the same issues that apply to stationary tanks also apply to tanker trucks, except that truck tanks never get a chance to settle. In addition, have you ever considered how much dirt gets into that tanker while it is delivering fuel to a customer, potentially a customer in an extremely dusty environment? As fuel flows out, air is sucked in to displace it. Is there anything protecting the inside of the tank from all the dust in the air? Generally not. Venting is typically completely unprotected.
Storage tanks: Onsite bulk storage tanks typically see less rapid turn-over than terminal tanks. In addition to those issues, yard and jobsite tanks can also develop serious problems with other sources of contamination, such as the ingress of dirt and water, condensation, rust, corrosion, microbial growth, glycerin fall-out and additive instability. Time and temperature become big factors affecting fuel quality.
Dispensing process: How far does your diesel need to travel between the bulk tank and the dispenser? The more pipe it runs though, the more potential there is for contamination. Are your dispenser nozzles kept clean? Are they ever dropped on the ground? Then what? What about the vehicles' fuel tank inlets, are they clean? Think about the extremely tight tolerances in your fuel system, then take another look at housekeeping issues. You will see them through new eyes.
Onboard fuel tanks: Contamination continues even after the fuel is in the equipment. What has that tank seen in the past? Has it been left stagnant for long periods? What kind of protection is there on the equipment's air intake vents? Heavy equipment does hard, dirty work.
Engines: Unfortunately, even if the fuel in your tank could be perfect, additional contamination is generated by the fuel system itself. Wear particles are created by mechanical friction. High heat and extreme pressure generated inside the modern engine, lead to coking and the creation of carbon products at the injector. Much of this internally produced particulate is returned to the fuel tank along with the unburned diesel.
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Water is the Enemy of Diesel Engines ( " All diesel contains some percentage of dissolved water. " )
Water has always caused rust and corrosion of fuel system components and infrastructure. Modern fuel systems are so much less tolerant than lower pressure systems, that manufacturers now specify zero free water must reach the engine.
DIRECT DAMAGE CAUSED BY WATER
Water causes damage to both fuel tanks and engine parts. Rust and corrosion in the tank create hard particulate that is passed along in the fuel, causing engine wear. Component life is also shortened by water etching, erosion, cavitation and spalling, such as:
injector
Rust: In contact with iron and steel surfaces water produces iron oxide (rust). Rust particles that get into the fuel, like other hard particulates, will cause abrasive wear to parts. Premature wear can cause part failures.
Corrosion: Corrosion is one of the most common causes of injector problems. Water combines with acids in the fuel to corrode both ferrous and non-ferrous metals. This is made worse when abrasion exposes fresh metal surfaces that readily corrode.
Abrasion: Water has lower viscosity than diesel, therefore providing less of a lubricating "cushion" between the opposing surfaces of moving parts. This leads to increased abrasive wear.
Etching: Etching is caused by water-induced fuel degradation which produces hydrogen sulfide and sulfuric acid that "eat" metal surfaces.
Pitting and Cavitation: Pitting is caused by free water flashing on hot metal surfaces. Cavitation is caused by vapor bubbles rapidly contracting (imploding) when exposed to sudden high pressure, which causes them to condense back into a liquid. These water droplets impact a small area with great force, causing surface fatigue and erosion.
Spalling: Occurs due to hydrogen embrittlement and pressure. Water is forced into microscopic cracks in metal surfaces. Then, under extreme pressure, it decomposes and releases hydrogen in a “mini-explosion” which enlarges the cracks and creates wear particles.
Ice: Free water in fuel can freeze, creating ice crystals that behave just like any other hard particulate. They can create wear in fuel systems and (in large volumes) clog fuel filters. A fuel filter's job is to protect the engine by stopping hard particulate. Engines and filters do not differentiate between dirt and ice. Damage caused by ice can be hard to correctly diagnose since the ice will melt and disappear long before a lab examination can occur.
INDIRECT DAMAGE CAUSED BY WATER
Water also contributes to or aggravates a number of additional issues, like the following:
Soft Solids: Water is polar. Certain chemicals in additives are polar. Hydrocarbons are non-polar. This means that water and polar chemicals are attracted to each other. In the presence of free water, the chemical molecules will sometimes disassociate themselves from the hydrocarbon chain of the additive and combine with water molecules to form a new substance. The new material is a soft solid that precipitates out of the fuel and can rapidly clog filters or create engine deposits.
Microbial Growth: Like most living organisms, bacteria and fungi (molds) need both food and water to survive. If free water is present microbial growth can proliferate, creating slimes that foul your fuel and acids that corrode your tank and fuel system.
Fuel Oxidation: Free water accelerates the oxidation process and encourages the formation of acids, gums and sediments known generally as fuel degradation products.
FORMS OF WATER IN DIESEL
saturated
All diesel contains some percentage of dissolved water. The water molecules remain part of the fuel until there are too many of them. The point at which the fuel can hold no more water is called the saturation point. The quantity of water in fuel is measured in ppm (parts per million). As long as the water stays below the saturation point as dissolved water it is typically not too much of an issue. Significant problems start when water separates from diesel and becomes free or emulsified water. Emulsified water is another form of free water; the droplets are simply so small as so well mixed into the fuel that they remain suspended rather than dropping to the bottom. There are no "droplets" when water is fully dissolved in fuel.
HOW DOES WATER GET INTO FUEL?
Water can come from a wide variety of sources, some of which can be extremely difficult to control.
On delivery from supplier
Free water fall-out (beyond saturation point)
Condensation in tank
Leakage into tank (rain, pressure washing, ground water...)
Ingress from atmosphere (humidity)
Human error (unprotected vents, fill ports, seals...)
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DIESEL ADDITIVES CAN STILL HARM ENGINES
Instability Can Create Solids in Fuel
sludge
Much of the world is required to use Ultra Low Sulfur diesel (ULSD).
With the removal of sulfur, fuel properties change radically, requiring the increased use of additive in order to meet specifications. In the
real world, maintaining these fuel properties can be a challenge. Diesel is tested at many points along the distribution channel, from refinery
to terminal to distributor to end user. Chemical additives are used to correct or enhance the fuel at each of these locations.
ADDITIVE DROP-OUT
Chemically speaking most additives are very similar to diesel itself (i.e. long chain hydrocarbons) so that they dissolve into the fuel. Additives are composed of a long hydrocarbon "tail" at the "head" of which there is another element, the one intended to have a beneficial effect on the diesel. This head typically contains atoms of nitrogen, oxygen, and/or sulfur in addition to carbon and hydrogen. Unlike the hydrocarbon tail, the head is polar. The beneficial element is intended to stay dissolved in the fuel so that it can do its job. Since head elements are polar, they have a strong tendency to want to escape from the non-polar hydrocarbons and associate with other polar substances such as water, metal, dirt, degradation particles or asphaltenes. You might think of them as being magnetically attracted to each other.
Sometimes, usually under adverse circumstances, the polar elements manage to come out of solution and form a bond with other polar elements. When this happens, there are two consequences:
The chemical may no longer be doing the job it was intended to do.
The chemical, now bonded with another substance, drops out of solution and turns into a soft contaminant in the fuel.
This phenomenon is most frequently observed in the presence of poor fuel storage conditions and fluctuating temperatures. Water, improper blending practices, and cold temperatures are leading contributors to these problems.
IMPACT ON ENGINES AND FILTERS
When unstable additive drops out of solution, it forms soft, sticky, solids which can cause rapid filter plugging and deposit formation. Engine manufacturers have observed injector deposits caused by these soilds, which are chemically identical to the substances found in many rapidly plugged filters, especially the high efficiency filters specified by OEs to protect HPCR systems.
The image to the right is of filter media at 1000x magnification under a scanning electron microscope (SEM).
The media was cut from a high efficiency filter of the type used in high pressure common rail fuel systems. This filter clogged in under 30 minutes of use. Between the media fibers you will notice a film. This kind of soft contaminant coats media as if it were covered in plastic wrap, effectively disabling the filter.
filterThe filter to the left has been completely disabled by soft contaminant. It looks clean because it did not have the time to become loaded with dirt. Instead, you will notice a sort of sheen, as if the filter media had been coated with wax. This is not due to wax (fuel gelling), but to soft contaminants that have dropped out of solution in the fuel. The pink color is red dye from off-road diesel. Upon further analysis, these soft contaminants were found to have chemical profiles identical to certain components of common diesel additives such as corrosion inhibitors, cold flow improvers, lubricity improvers and others. One thing that is important note, the root causes of this specific chemical instability are not yet completely understood. They are under rigorous investigation by Donaldson Company and other industry leaders.
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MICROBIAL BACTERIA IN DIESEL FUEL
Microbes Eat Fuel and Multiply
microbes
Microbes are present everywhere, but without food and water they cannot multiply; diesel is food. When there is free water in the tank, the microbes
have everything they need to grow, fouling fuel and damaging tanks in the process. By some estimates, a microbial colony can consume up to 1% of
your fuel investment, while destroying the rest.
MICROBES NEED FOOD AND WATER
Microbial colonies proliferate at the interface between fuel and free water
that has settled to the bottom of the tank. This creates a “rag layer” which gives them everything they need to thrive. Warm temperatures will accelerate the growth of microbial colonies. Microbial growth can occur in any diesel fuel. Biodiesel, being made from plant and animal fats, makes especially good food for these bugs and contributes to the increased incidence of biological growth problems seen in recent years. Bugs can grow in petro diesel as well. Stagnant fuel is especially at risk.
DEGRADED FUEL BECOMES UNUSABLE
With time the microbial colony proliferates beyond control. This leads to acid formation, rust, corrosion and filter plugging. Fuel degrades to the point that
it can form a slimy sludge that is unusable as fuel.
gross stuff
This process can occur in a bulk storage tank or in a piece of equipment that is left idle for a long period of time. To the right is a classic example of what is called filter “leopard spotting”, which requires the filter to be exposed to both microbes and water. The black spots are microbial colonies. Live or dead, microbes will clog filters and damage fuel systems. It is important to eliminate bugs completely and permanently.
MICROBIAL GROWTH vs. ALGAE
Microbial colonies, sometimes incorrectly referred to as algae, are actually bacteria or fungus. Algae needs light to live and grow, there is no sunlight in a closed fuel tank so algae cannot survive
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THE DEGRADATION OF FUEL OVER TIME
Diesel Fuel Has a Shelf Life
ULSD and biodiesel both have reduced stability in storage compared to traditional high sulfur diesel. While it is true that removing sulfur improves stability, the hydro-treating process also tends to destroy naturally occurring antioxidants. As a result, some ULSD fuels may require the addition of a stabilizer to prevent the formation of peroxides that lead to soluble gums. Shelf life recommendations for petro diesel and biodiesel blends are less than a year, and sometimes as low as 2 months, depending on factors below.
CONSEQUENCES OF UNSTABLE FUEL
Oxidative instability in petro diesel or biodiesel leads to the formation of fuel degradation products. These include:
Gums: sticky varnishes that contribute to corrosion and injector deposits, causing over or under fueling
Sediments: particulate that clogs filters and causes abrasive wear to fuel pumps and injector.
Acids: cause corrosion of tanks and fuel systems, leading to hard particulate formation and premature parts failure.
Thickeners: increase fuel viscosity, leading to incomplete combustion and reduced fuel economy
Common consequences of fuel degradation include loss of power, increased fuel consumption, premature filter plugging, damaged fuel pumps / injectors and increased maintenance costs. Generally speaking, fuel degradation decreases the combustion quality of fuel. You may notice symptoms such as black smoke, harder starts and reduced engine performance.
FUEL DEGRADATION IN STORAGE
Time is the enemy of diesel fuel quality. Oxidative instability can occur slowly during long-term storage or be accelerated by warm temperatures, the presence of free water and contaminants. This degradation can lead to high acid number, high viscosity and the formation of gums and sediment (fuel degradation products). Biodiesel is especially susceptible to the effects of higher temperatures. Data sets vary, but a good rule of thumb is that the oxidation rate increases 2.2 times for every 18°F/10°C.
Example: biodiesel blend stored at various temperatures
68°F/20°C: marginally OK after 6 months
77°F/25°C: degraded after 6 months
86°F/30°C: degraded after 4 months
Water in fuel can accelerate the oxidation process, but even worse are the effects of the microbial infestations that can grow as a result of water in the tank. These bacteria and fungi literally feed off your fuel, leaving behind acids and various forms of black, sticky, slimy materials that corrode your tank and plug your fuel filters. Whatever the contributing factors fuel degradation cannot be reversed, the key to success is to prevent it before it occurs with good fuel handling practices.
FUEL DEGRADATION ON VEHICLE
Fuel degradation can occur rapidly on-engine when excess diesel is heated to extreme temperatures inside high pressure common rail systems and then returned to the fuel tank along with black carbon particles created at the injector. High thermal stability is important for diesel fuel to function effectively as a heat transfer fluid inside the HPCR fuel system. Future injector designs are expected to employ even higher pressures and temperatures than today to achieve better combustion and lower emissions.
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Filters Capture More Than Dirt
frozen pipe
Cold weather operability can be a huge problem. Equipment won't start in the morning or even if it does, it might stop suddenly in the middle of a job. These issues are usually caused by solids created in the fuel as the temperature decreases.
Engines and filters do not differentiate between particles. Hard or soft, contaminant or pure hydrocarbon, solids in fuel will cause trouble. These problems are made worse by new-age fuels, the sensitivity of modern engines and the high efficiency required of filters designed to protect them.
ICE
When the weather turns cold, free water in fuel will freeze. Ice crystals will behave like any other hard particulate, loading in filters or causing abrasive wear to fuel systems. In large quantity, ice can completely block filters or pipes, preventing fuel flow. De-icers may be able to help get you running in an emergency situation, but adding alcohol to diesel is generally discouraged. Keeping free water out of the fuel is by far the best solution, learn more by reviewing solutions for water problems.
GELLING
Like water, hydrocarbons turn solid when they reach their "freezing" point. Unlike water, however, they do not turn into ice. Instead, they turn into a thick, waxy substance that cannot flow through filters. This is what is referred to as "gelling". It is a characteristic of both petro diesel and biodiesel. Diesel fuel is not one "thing". Instead, it is a complicated mixture of thousands of potential compounds, each with different chemical and physical properties. The particular formula is determined by the refinery at time of production. Typically about 250 different chemicals are included, mainly hydrocarbons. Precise freezing temperature varies widely from one hydrocarbon to another, which directly relates to winter operability issues. “Winter diesel” contains a blend of hydrocarbons with generally lower freeze points than “summer diesel”.
In some countries there is a classification of fuel called "Arctic diesel" for extremely severe conditions down to -40°F/C and below. An easy way to think of fuel "freezing" is to compare vegetable shortening to vegetable oil. Both are essentially the same thing, but shortening is solid at room temperature whereas oil is liquid. The same is true of hydrocarbons. At a given temperature, some may be liquid while others assume the soft, waxy state which is the ”frozen” or solid phase of hydrocarbons. This is commonly referred to as gelling.
WINTER FUEL
When cold weather threatens, refineries and distributors can and do improve diesel's cold weather operability properties in several different ways. They can:
Select less waxy crude oils upstream of the refinery
Extend the refining process to eliminate waxy elements with higher melt temperatures (i.e. they freeze at lower temperatures)
Dilute fuel with #no.1-D diesel or kerosene, which has lower wax content
Treat diesel with low-temperature operability additives (cold flow improvers)
Fuel suppliers manage hydrocarbon blends at the time and place of sale but cannot control unusual weather swings or fuel that is kept in storage or transported to colder climates. DO NOT add heating oil to your fuel in an attempt to lower the cloud point. This practice is strictly forbidden by most equipment manufacturers and may void your warranty.
PREDICTING COLD WEATHER OPERABILITY
There are a number of tests intended to predict the cold weather performance of a certain fuel. Their relative merits are the subject of some debate. No independent test data regarding their usefulness has been published since the advent of HPCR fuel systems, high efficiency fuel filters, ULSD and widespread biodiesel.
Cloud Point: When diesel cools, wax crystals begin to form and a noticeable white haze (or "cloud") appears. The wax drops out of solution and starts getting caught in fuel filters and lift pumps. Actual cloud temperature varies based on fuel characteristics. Some low quality fuels may have cloud points as high as 40°F/4°C, but most good quality fuels will have a cloud point around 32°F/0°C (untreated). As a rule, cold flow improvers do little to lower cloud point. There are some cloud point depressants that can significantly lower a fuel's cloud point, but their use is generally discouraged because they can actually work against the anti-gels that are intended to keep fuel flowing. The best way to lower cloud point is through the addition of a hydrocarbon with lower wax content such as #no.1-D diesel.
Cold Filter Plugging Point CFPP: This is the temperature at which wax crystals will rapidly plug fuel filters, starving the engine of fuel, preventing it from starting or stopping it cold (usually when least convenient). Cold flow improvers can depress CFPP by several degrees. They do not actually lower waxing temperature, but rather work on the wax crystal itself. They alter the size and shape of the crystals so that the fuel flows better and passes through filter pores at lower temperatures.
* A note of caution: Most cold flow improvers do not work as well in ULSD as they did in higher sulfur fuel. Be sure that performance claims are based on test results using ULSD. If not, they are irrelevant. The common test method for measuring CFPP is ASTM D6371. It was developed in 1965 and uses rapid cooling methods to determine the temperature at which 20cc of diesel will no longer flow through a 45 micron wire mesh in 60 seconds or less. A CRC (Coordinating Research Council) study in 1981 determined that CFPP is not an accurate predictor of real world performance. It tends to over-state minimum operating temperatures (i.e. cold weather performance in the real world is not as good as the test would make it appear).
Low Temperature Flow Test LTFT: This test (ASTM D4539) is considered to be somewhat more accurate at predicting the performance of additized fuels and is frequently recommended for North American heavy duty trucks. Instead of using an unrealistic rapid cooling method, this test method allows diesel to cool slowly (1°C per hour), which is much more representative of real world conditions. In this test 200cc samples are drawn through a 17 micron mesh screen using 20 kPa vacuum. The LTFT point is determined when 90% of the sample no longer passes through the screen in 60 seconds or less. Although deemed more accurate than the CFPP test at predicting cold weather performance in North America, the LTFT uses a 17 micron mesh screen in determining acceptable flow. This is finer than the 45 micron mesh used for CFPP, but one can still reasonably question its ability to predict fuel flow through the high efficiency 2 micron filters used to protect today's HPCR engines.
Pour Point: The temperature at which diesel freezes is called its pour point. At this temperature fuel will freeze solid in lines. Pour point is irrelevant in terms of predicting cold weather operability because it is lower than cold filter plugging point. If fuel cannot pass through filters to the engine, the vehicle will not run. In the absence of other complications, gelled or cloudy diesel should clear as it warms. The wax crystals will dissolve back into solution and the fuel will once again be perfectly liquid. If the fuel does not clear when warmed, then another factor is at work in addition to cold temperatures. Most likely additional chemistry is present and a reaction has taken place creating soft solids that do not melt at normal operating temperatures.
GLYCERIN
Gelled fuel and glycerin solids are frequently confused with one another. But while gelled fuel is a natural phenomenon caused by cold alone, glycerin is an entirely different chemistry that is only present in biodiesel. Glycerin and other related substances (glycerols) are byproducts of biodiesel production and are not found in petro diesel. Regulations require the removal of virtually all these materials, but even at very low levels they can immobilize a fleet. As long as glycerin remains warm and liquid, it generally causes no immediate problems. At low temperatures, however, glycerin assumes a solid waxy state. It drops to the bottom of tanks, gets caught in fuel filters, and forms sticky, corrosive engine deposits.
Glycerin can turn solid at relatively high temperatures, sometimes as high as 55°F/13°C or above. Unlike standard gelled fuel, glycerin typically does not re-liquefy when the temperature goes back up. Once solid, glycerin tends to stay solid, even at high ambient temperatures. This container of in-spec B100 was completely liquid until it was cooled off in a refrigerator at 40°F/4°C. At that temperature, a solid lump of glycerin formed and settled to the bottom. This solid did not re-liquefy, even when it was heated well beyond normal on-equipment fuel temperature. Although the origins are somewhat different, many of the consequences of glycerin and gelling are the same. Cold weather causes soft solids to form, small quantities of which clog fuel filters and prevent fuel flow. This prevents engines from starting or stops them due to fuel starvation. In cold climates, more and more indoor garages are being built so that fleets can be parked inside over night to be sure the vehicles start in the morning.
CONSEQUENCES OF SOFT SOLIDS
cold glycerin
Soft waxy solids will rapidly disable filters, regardless of the age of a filter. Where will these solids form? If fuel is delivered cold, then solids may be pumped into your tank by the supplier. If the fuel cools off in the bulk tank, then solids can fall out at that point. If your diesel doesn't get cold until it is already in the onboard fuel tank, then that is where it might solidify. Wherever they form, soft solids will quickly clog the first filter they encounter.
The image to the right is an extreme case of a filter clogged with glycerin. Usually you will see nothing this dramatic. Instead, your filter will likely appear clean, with only a faint waxy sheen to the media or a small amount of deposit in the bottom of the filter can. Here you see images of cellulose, average efficiency filter media under a Scanning Electron Microscope.
celulouse
The first image to your left is of clean cellulose media. Notice the free,
darker, areas between the fibers.
”SEM"
The second image, to your right, is cellulose and glass media of the type used in primary onboard fuel filters. The areas between fibers have been completely clogged with glycerin. It can take only a few spoonful's of solidified glycerin or other soft solids to completely disable a fuel filter.
Onboard cellulose
The final image, to your left, is relatively low efficiency cellulose media of the type sometimes used on fuel dispensers. It also is caked over with glycerin. Nothing will flow through a filter clogged with glycerin. Luckily for the equipment owner, this soft waxy glycerin was caught and prevented from reaching the engine. The unfortunate consequence, however, was that these filters likely had very short lives.
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