x Items in my bag 0
    Orders placed after 12:00pm on 21st December will be dispatched in January 2024. Merry Christmas!

    diesel fuel contamination: causes and prevention

    When using diesel for commercial applications, itís important to be aware of the risks of fuel contamination so that youíre best placed to avoid using contaminated fuel in your vehicles and equipment, and are able to react quickly to resolve issues should contamination occur. After all, contaminated fuel can lead to costly and potentially dangerous damage.

    In years gone by, diesel fuel could be stored for 10 years or more without a problem. Then, refineries came under pressure to maximise the yield from crude oil and reduce emissions. Hydrocracking and other processes and methods were introduced to help achieve these goals, but one of the results of this was that diesel fuel became fuel less stable. Today, the average shelf life of diesel fuel is around 6 and 12 months.

    Browse Diesel Storage Tanks

    Over the last decade there has also been a shift to using fuel which is a blend of petrochemical diesel with a small amount of biodiesel. The benefits of modern fuels in reducing carbon dioxide emissions are important. However, the unstable precursors injected into diesel fuel in the market today make it prone to contamination in supply lines and diesel storage tanks.†

    Fuel that is poor in quality or contaminated with water, dirt, or microbial growth can cause engine problems and bring your fleet or agricultural equipment to a halt. Most of these impurities cannot be filtered out using a regular air filter, however specialist diesel tank filters are available to help remove air and other contaminants from a system. There are also a number of measures that can be taken to prevent contamination from entering your fuel tank and harming your vehicle.

    Letís take a closer look at the various ways contamination can occur, the effects of using contaminated diesel in your machinery, and ways to prevent this diesel contamination.

    what is diesel contamination?

    Diesel contamination is the presence of particulate matter, bacterial growth, and other polluting substances in diesel fuel. It can cause sludge and varnish deposits to build up in diesel engines, and this build-up can clog injectors, reduce power, and ultimately cause engine failure.

    Diesel fuel can become contaminated in many ways. Some contamination comes straight out of the refinery, and other contaminants are added during processing or transit. The most common way contamination happens is through improperly maintained diesel tanks.

    The most common causes of diesel contamination in fuel tanks are:

    water in diesel tanks

    Water can enter a diesel fuel storage tank when condensation collects in the tank. Rain and run-off water can also enter the tank through hatches, breathers, or vents. Water triggers chemical reactions that break down diesel, and it is usually the catalyst in the formation of bacterial growth.

    microbial growth or "diesel bug"

    This type of contamination occurs when bacteria, which are ever-present in water, feed on the hydrocarbon in diesel fuel and multiply. Up to 100 species of bacteria can attack unprotected diesel systems, and they can double their population in as little as 20 minutes. These biomass formations can degrade the quality of diesel fuel and restrict its flow.

    solid particulates

    These include the sand and dust that enters the fuel tank through poorly sealed air vents, rust from deteriorating tank surfaces, and traces of metal and metal alloys that might come in contact with diesel fuel during processing, transportation, or storage.

    fuel additives

    Other sources of contamination include fuel additives that contain alcohol or other chemicals which react with diesel fuel. Many of these chemical reactions introduce water into the fuel and create the problems described above.

    The Consequences Of Diesel Contamination

    Contaminated diesel causes problems by plugging up fuel filters, clogging injectors, and generally creating instability in the fuel delivery system of equipment.†
    The problem is not usually an issue of safety; it is a matter of efficiency. You lose power, and your machinery guzzles more fuel as it is forced to work harder to keep running. Some engine manufacturers also void the warranty if an engine is damaged by poor-quality fuel, meaning you have to incur expensive repairs or replacements. However, if left unchecked, this can lead to machinery or equipment that fails in a way that makes it unsafe to use.

    Some of the specific problems that diesel contamination can cause in fleets or equipment include:

    • Water in diesel can corrode engine components and cause rust to build up in the fuel system. These problems not only reduce the efficiency of your engine but also cause incomplete combustion, which leads to higher levels of carbon dioxide being released into the environment.

    • Diesel bug usually grows in the rag layer, where diesel fuel and water meet. It eventually appears as a biofilm that can get sucked in the engine, blocking filters and damaging injectors. Microbes also produce acid that degrades the fuel and corrodes storage tanks.

    • Sediment in diesel fuel can cause the obstruction of filters, which reduces the flow of oil to the engine and causes it to run hotter. If this happens, there is a greater chance of engine failure.

    How To Tell If Diesel Is Contaminated

    The easiest way to tell if your diesel is contaminated is to examine its colour and consistency. Look at the diesel through clear glass and see if there are dark patches or suspended particles. Clean, undyed diesel fuel should be amber-green. It will darken if it is contaminated or degraded. Look for other signs, such as residue on the diesel tank wall.

    Another way to tell if your diesel is contaminated is to look out for problems in the performance of your vehicle or equipment. The symptoms you see will depend on the type of contaminant and the amount of contamination, but some common issues include:

    • Excessive smoke, usually blue or black, coming out of the exhaust pipe during operation

    • Reduced engine power and torque, including trouble achieving peak performance

    • The engine doesn't start at all

    • Rough idle

    • Sluggish throttle response

    • Rough shifts in automatic transmission systems

    • Chugging or hesitation when you accelerate

    • Poor fuel economy

    • A strong rotten egg or stale beer odour in the cabin of the vehicle

    These symptoms may appear abruptly, gradually, or intermittently. If you encounter any of these problems and you recently filled your tank with diesel fuel, take your vehicle to a mechanic immediately. Contamination is only one of many possible explanations, so your mechanic should determine the cause of the problem before attempting any repairs.

    How To Prevent Diesel Contamination

    The best way to prevent diesel contamination is to make sure contaminants don't get in your storage tank in the first place. To do this, you should always buy diesel fuel from authorised sellers and ensure you have tight seals on your tanks and above-ground storage facilities.

    Here are other tips you should follow to prevent diesel fuel contamination:

    • Ensure diesel is stored in a high quality diesel storage tank. The tank should prevent moisture and other contaminants from mixing with the fuel, and be designed to remain reliable in all conditions.

    • Keep your diesel storage tank full at all times. The less air space a diesel tank has, the less room for condensation and other contaminants to build up.

    • Ensure there are no leaks in your delivery system because this could allow moisture and other contaminants present in the air to get into the fuel storage tank.

    • Treat your diesel fuel with biocides and fuel stabilisers. Biocides prevent bacteria and fungi from growing in the water in diesel. Fuel stabilisers guard against contamination by moisture and oxidation, and they also help prevent the gummy deposits that form in old fuel. If you are storing diesel fuel for more than a few months, use a fuel stabiliser to ensure it is still usable when you need it.

    • Use Fuel Water Separator (FWS) filters. FWS filters remove solid particulates and free water in diesel fuel. Some diesel storage tanks come with these filters.

    How To Correctly Store And Dispense Diesel

    Diesel fuel can last for more than a year when stored in good conditions. As a rule, you should always store your diesel fuel in cool conditions of around 21 degrees Celsius and treat it with biocides and stabilisers.

    Other measures that can extend the shelf life of your fuel are:

    • Store diesel fuel in containers specifically designed for fuel storage. Any container you use should have a special rubber seal on the lid to prevent air from entering, as well as a pressure relief valve. If these features are not present, there is a high likelihood that your diesel fuel will become contaminated with moisture or other pollutants over time.

    • Keep diesel tanks upright, full, and with their caps secure. Never store diesel fuel in an open container or where it can be exposed to the elements.

    • Make sure the diesel tank is clean and dry before filling. Remove any objects such as leaves or grit that may have fallen into the tank. Close the cap tightly to prevent moisture from entering the tank.

    • Keep diesel fuel tanks away from heat sources such as radiators, furnaces, or stoves. Extreme temperatures also can cause problems with diesel fuel quality, so don't store your diesel tank in direct sunlight or in a place where it will freeze. The best location is inside a building where temperatures are more constant and moisture levels are lower.

    • Make sure to use diesel fuel within its storage life. If you have stored diesel for two years or more, make provisions to replace it with fresh fuel.

    • Consider investing in underground storage. Installing underground storage tanks will be costlier than setting up above-ground tanks. However, underground tanks are less susceptible to fire and explosion risks and general damage. Underground tanks also keep diesel fuel cooler and are less likely to be contaminated by water and oxidation. If you are using above-ground storage tanks, consider a canopy or other enclosure to reduce exposure to the sun and water sources.

    • Empty and clean storage tanks at least every 10 years. Thorough mechanical cleaning eliminates biofilm and other contaminants and helps extend the useful life of your fuel and storage tanks.

    Browse Diesel Storage Tanks

    Thank you for subscribing to our newsletter