AFC Series Diesel and Gasoline Fuel Treatment
and Tank Cleaning Additives

One gallon of AFC-705 or AFC-710 cleans a full 5,000-gallon fuel tank for a regular preventative maintenance treatment. If you are treating a tank that is more than five years old for the first time, or you are treating a tank that you know is contaminated, it is recommended that you use a double dose, using one gallon of fuel to 2,500-gallons (see other treatment ratios below). This full spectrum additive package cleans the entire diesel fuel system, restores diesel fuel quality and provides Optimal Diesel Fuel Quality for engines and storage tanks, improving fuel economy, reducing emissions and lowering operating cost, maintenance and down time.

It is generally agreed that most engine failures originate in the fuel tank. Frequent fuel filter changes, fuel dialysis and tank cleaning are generally viewed as good house keeping, and have become accepted as standard periodic maintenance.

The normal aging process of the fuel is often accelerated by microbial contamination, chemical incompatibility and condensation of water in the system. Oxidation, polymerization and stratification will lead to darkening of the fuel, the build up of tank sludge, filter plugging, corrosion, and fuel breakdown. We will see a slimy, jelly like layer develop in the water-fuel interface, while a bio-film is growing on the bottom, walls and baffles of service and storage tanks, inside fuel lines and delivery systems.

The process of fuel breakdown is most severe in the bottom of our tanks. Every time we fill our tanks, we mix and contaminate the fresh fuel with our residual fuel, and add new oxygen, which accelerates the problem. Because we primarily use the higher and therefore dryer layers of the diesel fuel, it is easy to overlook the symptoms of this continuous process of fuel breakdown.

Suddenly we get a wake up call, and experience some or all of these symptoms:

All of this can be prevented by simply monitoring fuel quality, and using the available AXI technology.

The surfactants and dispersants in AXI Fuel Catalyst completely break down and dissolve the tank sludge and bio-film. It eliminates clogged filter elements and recovers the BTU value that would otherwise be lost.

Traditionally tank cleaning meant filtering the fuel in the tank, or removing the fuel for filtration, or complete fuel disposal often in conjunction with opening the tank and physically removing tank sludge and bio-film. All these techniques are time consuming, costly and only partially effective, in particular when we realize that filtration will only remove the suspended debris and has no effect on the bio-film growing on tank walls, bottom and baffles, or on the process of fuel break down. At best we can expect only temporary relief at an extremely high price.

We recommend the use of AXI Fuel Catalyst to completely decontaminate and clean the entire fuel system, with the simultaneous installation of an In-line Fuel Conditioner to insure continuous Optimal Fuel Quality, enhanced combustion, and reduced emissions.

The AFC catalyst enhances and complements the effects of the In-line Fuel Conditioner. You would also use AFC Series Additives if you are beginning a Fuel Maintenance Program that would involve periodically treating a tank with a TK Series Portable, and MTC Series Mobile, or an STS Series 6000 or Series 7000 Automated Fuel Conditioning and Tank Cleaning System. Review the process for using AFC with a circulation system in Guide #5 “Cleaning a Fuel Tank also available at the Guides Menu along the left side of any page on this web site.

When the EPA mandated the switch to 15 ppm of sulfur content in diesel fuel in 2007, introducing the era of Ultra Low Sulfur Diesel (ULSD) Fuel, the agency allowed for a phase-in period, but by 2015, all diesel fuel both on-road and off sold in the U.S. had transitioned to ULSD. This sulfur removal has caused a major problem with microbial growth in diesel tanks, both storage tanks and operating equipment tanks, because the natural biocide provided by the sulfur in the fuel has been substantially eliminated.

Sulfur acts as a natural biocide that had helped prevent microbial growth in diesel fuel tanks. This microbial growth is not algae, although many people think it is. The slimy debris that clogs fuel filters and is visible floating around in fuel is actually a bio-mass that is a byproduct of the reproduction of the microbes that utilize the water in the tank bottom as a habitat, feeding off the additives in the diesel fuel at the fuel-water interface in the tank bottom. Removing the sulfur made the fuel much less resistant to fuel microbes, including fungus, mold, and bacteria.

Microbes, mold and bacteria may be introduced into a fuel tank with a fuel fill-up, but it is more common for this contamination to come in through the air vent. As fuel is used, it is replaced with air drawn into the tank through a vent, and this air contains both moisture and the microbes and fungi that, over time, develops into a real problem. Storage tanks, especially above ground tanks, “breath” as the tank warms during the day and the heated fuel expands, pushing air out of the tank.  At night the fuel contracts as the fuel cools, drawing moisture and contaminants in through the vent.

It may take up to nine months for the microbial growth to develop before the fuel starts showing the symptoms of microbial growth:

• Clogged and slimy filters
• Dark hazy fuel
• Floating debris in the tank
• Sludge build-up in the tank bottom
• Loss of power and RPM
• Excessive exhaust smoke
• Corroded, pitted fuel injectors
• A foul odor emitting from the fuel tank

Any of these symptoms indicate a serious fuel problem.

Preventing this situation is critical. The use of an air vent breather that prevents the drawing in of moisture and microbes in through the vent is an absolute must. Desiccant Fuel Tank Breathers contain material that absorbs moisture as the air is drawn into the tank, and filters dust, pollen and other organic components, as well as dirt, grit, and other particulates that carry the micro-organisms, bacterial growth, fungal growth, enzyme activity, yeast, mold, and pollen into your fuel tank. Stopping this flow should be the first step to stopping the problem.

The most critical steps you can take in controlling microbial growth is in robbing the microbes of their habitat. Checking for water on a regular basis (every 30 to 60 days) using Kolor Kut Water Finding Paste and removing any water that is detected will reduce the likelihood of an infestation in your tank, but will not absolutely prevent it as even residual water left behind when a tank bottom is pumped to remove water can harbor an infestation.

Using a device known as a Water Eliminator, available for smaller tanks in a 12″ size and a 31″ version for use in storage tanks, crystals in the Water Eliminator absorbs the water but will not absorb diesel fuel. The water in the bottom of the tank will be held in the device and not spread over the bottom of the tank. At periodic inspections at fuel fills, when the device has absorbed its full capacity of water remove it and replace with another for ongoing protection.

Periodic treatment of fuel with AFC dissolves the bio-mass, and periodic circulation of the fuel is necessary to assure the tanks are clean, free of water, and any microbes left behind is not reproducing. The LG-X Series In-line Fuel Conditioner sees to that.

Unfortunately, by the time you realize you have a problem, the effectiveness of biocides are limited. If a heavy bio-film has accumulated on the inside surface of the tank or other fuel system components, the biocide may not be able to penetrate this film to reach the organisms living deep within the film. You may see short term relief, but the problem quickly returns as the remaining organisms further reproduce.

Frequently, the application of a biocide aggravates the situation and converts what bio-film that is treated into solids, creating a real fuel filter nightmare. The introduction of a biocide into a fuel tank results in the organic materials turning into a grit that settles to the tank bottom. Then, each time you re-fuel, these materials are stirred up and find their way into your fuel line. As a further complication in the use of biocides, the removal of water from a tank bottom that was treated with biocides must be disposed of appropriately because biocides are toxic.

As diesel fuel ages and it is exposed to air, water, and other factors, its heavy-end asphaltene content will become unstable and start to drop out of suspension in the fuel. When old fuel appears dark or even black, this is caused by the agglomeration of the asphaltene component. As these solids grow in size, they drop to the tank bottom and add to the sludge and debris. They clog your fuel filters and the filters turn black. If you have ever looked inside a fuel tank, and the tank bottom appears to be painted with roofing tar, this is what the accumulation of the asphaltene debris looks like.

This asphaltene component is present in all fuels.  In the refining process, crude oil is separated into its components based on mass.  Lighter components become gasoline, while heavier components of the crude oil becomes diesel fuel, kerosene and other fuels.  Heavier still are the components that are the basis for lubricating oils and other petrochemical products, with the heaviest component becoming asphalt that paves our roads (hence the name “asphaltene”)

The AFC will, over a period of time with regular use, clean this accumulation in your tank, and with ongoing circulation through the LG-X Series In-line Fuel Conditioner, either mounted on your fuel line or, with periodic treatments utilizing a TK Series Portable, MTC Series Mobile,  FPS Compact or an STS Series Automated Enclosed Fuel Conditioning and Tank Cleaning Systems, will go back into solution, allowing the fuel to regain its “clear and bright” appearance. This returning dark fuel to bright fuel is where the term “Fuel Polishing” originated.

According to Caterpillar, ULSD has a shelf life, even when all basic fuel storage maintenance practices are followed by the distributor, of one year beginning when the diesel fuel leaves the producer, and six months for bio-diesel and blended bio-diesel. At temperatures above 86 deg. F (30 deg. C), diesel and bio-diesel fuel storage life is cut in half.

However, Cat contends that diesel fuels can deteriorate rapidly when fuel is “stressed”. The high pressure (in excess of 30,000 psi) and high temperatures (fuel is used as a coolant for high-pressure fuel injection systems) that the fuel endures as it is repeatedly recirculated back to the fuel tank is responsible for much of fuel degradation. Gums and resins that occur in diesel fuel under these stressful conditions are the result of dissolved oxidation products in the fuel that do not evaporate easily and do not burn cleanly. Excessive gum in the fuel will coat the inside of fuel lines, pumps and injectors and interferes with the close tolerances of the moving parts of fuel systems (Caterpillar’s publication SEBU6251-17 “Cat Commercial Diesel Engine Fluids Recommendations”, Page 45). Google the above publication number, although there may be more recent versions available online.

In today’s low sulfur fuel, many of the fuel components that contribute to the lubricating properties of the fuel have been removed. The components used to formulate the lubricity enhancers in AFC Series Fuel Catalyst work to offset the lower lubricating properties in two different ways, and over two different temperature ranges.

The two components together address corrosion, lubrication and friction problems over the entire engine operating temperature range, and inhibit the formation of acids. AFC lubricity enhancers will not change the fuel specifications in any way. The sulfur content, BTU value and other specifications will remain unchanged.

The principle benefit of AFC lubricity enhancers is the extended life of engine parts that rely on the fuel for lubrication. Keeping these parts operating normally solves many of the problems related to switching from a regular to a low sulfur diesel fuel. A small increase in available power will be noticeable due to lower friction.

Engine parts will be more resistant to acid corrosion and will show less wear due to carbon grit. As a result, engine lubricating oil will stay cleaner much longer. The mineral content, carbon grit, and acid forming compounds in the oil will be much lower. AFC lubricity enhancers will not interfere with crankcase oil additives. Instead, they may actually help them to do a better job.

As in any maintenance situation, the effectiveness of AFC lubricity enhancers does not replace good maintenance practices. However, its use will significantly reduce maintenance requirement and down time, while extending equipment life.

The use of AFC is highly recommended, in particular in situations with low sulfur, or low lubricity fuel. The lubricity enhancer and corrosion inhibitor package in the catalyst are designed to improve engine performance and increase the life of key engine parts while saving in fuel and reducing harmful emissions.

Review the Article on this web site “AFC Series Fuel Catalyst, Fuel Stabilizer and Tank Cleaning Additive — A Technical Discussion —” for a more complete and technical discussion of AFC Series Diesel Fuel Additives

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