Fuel Contamination: How to Identify and Prevent it? 

Fuel contamination can be difficult to avoid and can damage equipment and machinery. In this guide, we explore what fuel contamination is, how it happens and how you can ensure fuel contamination doesn’t affect your operations.

What is fuel contamination?

Put simply, contamination is when there’s an undesirable substance present in fuel. If it’s not discovered and the fuel is used in machinery, it can cause significant issues and damage mechanisms and, in worst-case scenarios, cause shutdowns. Sometimes the fuel can be treated, sometimes it has to be discarded. This depends on what the contamination is caused by. We mainly focus on diesel in this article, but other types of fuel can be affected. If DEF isn’t stored correctly and gets contaminated, it can lead to serious consequences for your equipment.

What causes it?

Contamination can be caused by a number of different things, including:

• Water: Water can enter fuel due to leaks, humid air entering the tank and water vapor that condenses inside the tank.
• Microbial growth: Microorganisms like yeast, fungi and other bacteria are always present in the air and can contaminate fuel at any time. This type of contamination is also known as diesel bug, which you can read more about below.
• Particulates: Rust, dust or other contaminants from other equipment and machinery can enter the fuel tank when it’s open or if the contaminants are airborne.
• Asphaltenes: Asphaltenes are a black, tar-like substance that forms in diesel fuel when it ages, when it’s heated or pressurized or if it becomes contaminated by other substances.

Contamination can be a serious problem. It can severely damage machinery and equipment, leading to downtime and the cost of repairing them. This can be detrimental  if it happens across an entire fleet.

What is diesel bug?

Diesel bug is a term for microorganisms that grow when diesel comes into contact with water. When diesel bug develops, it appears as a slimy, sludgy deposit that can range in color from dark brown to black and often has a distinctive rotten-egg smell. Affected fuel can cause engine damage, corrosion, black smoke, difficulty starting machinery and increased fuel consumption.

Fuel contamination symptoms

Contamination is normally only noticed when machinery and vehicles are affected, but if you know what to look out for, it can be caught before it’s used and causes any damage.

• Does the fuel look different? Has the fuel changed appearance and become cloudy or dark?
• Does it smell different? Contaminated fuel can smell different to normal fuel, either very bad or it could smell like varnish.
• Is there anything floating in it? If you can see any debris floating in the fuel, or sludge on the sides of the tank, this is an indication it’s contaminated.
• Is the tank damaged? Has the tank been damaged or are there elements of wear or rust that mean the fuel inside could have been compromised?
• Could water have got in? Could rain or water have gotten into the tank? This is a common cause of contamination.

If you think contaminated fuel might have been used, look out for these signs in machinery and equipment:

• Filters frequently become clogged or need to be replaced
• More smoke than usual from the exhaust
• Reduced engine performance
• Difficulty accelerating
• Check engine light may come on

If you notice any of these things, your fuel is probably contaminated and you should stop using it immediately.

Fuel contamination testing

While contamination can often be spotted by looking out for the signs above, sometimes you’ll need to test your fuel to identify if your fuel is contaminated. The process varies according to the type of contamination:

• Particulates and asphaltenes – If these are too small to identify visually, they can be identified by chemical analysis.
• Water – Testing kits are widely available that can identify whether the level of water in your fuel is above or below 30 parts per million.
• Microbial contamination – Microbial contamination is harder to identify. Tests for this kind of contamination, also known as diesel bug, normally require a fuel sample to be sent to a lab for analysis.

How to prevent fuel contamination

Fuel contamination is much easier to prevent than fix, so you should do your best to eliminate the chance of your fuel being contaminated. There are some set processes that can help.

Inspections

Visual inspections are likely to catch contamination once it’s already begun, but it’s better to identify signs of contamination early rather than risk your entire supply of fuel becoming unusable. We’ve already looked at the visual signs above, but look out for:

• Dark or hazy fuel
• Any evidence of rust inside the tank
• Floating debris
• Scum on the sides of the tank

Monitor and clean your tank

Keeping your tank in good condition is crucial in limiting the chances of contamination.

• Look out for any rust, either on the outside or the inside of the tank.
• Inspect seals, hinges and joints. If plastic or rubber seals perish or fail, it’s much more likely that water or other substances will get into the fuel.
• Pooling water on the top of the tank should be cleared away as soon as possible. In colder weather, the freeze-thaw effect can cause damage to the tank.
• As part of maintaining your tank, you should have it professionally cleaned. This is because sludge and other substances can be hidden at the bottom of your tank and may not be noticed on visual inspection. If your fuel level runs low, this sludge can be pumped out and into machinery, causing serious issues.

What to do if you have contaminated fuel

What you need to do depends on the severity of the contamination. 

If you have excess water or diesel bug in your fuel, you can try to salvage the fuel by using an additive or by fuel polishing (filtering the fuel to remove water, sediment and microbes).

If the fuel isn’t salvageable and the contamination is severe, you should drain the tank and fuel lines and clean the tank to remove any sludge or sediment. When you refill the system, flush it out with fresh fuel.

Avoid fuel contamination with a Western Global tank

As we’ve discussed, contamination can be costly and time-consuming. It’s better to avoid the risk of contamination altogether, and with a Western Global tank, your fuel has the best chance of remaining secure and uncontaminated. Our popular TransCube Global has a number of features that help to limit contamination, including:

• Removable inner tank – A removable inner tank makes inspection, cleaning and maintenance straightforward. Allowing you to stay on top of your fuel supply far more easily than other tanks.
• Manway access – Gives you access to the inner tank, making inspecting fuel and performing maintenance straightforward.
• Secure equipment cabinet – Ensures fuel, ports and other equipment are kept safe and reduces the opportunity for contaminants to enter your fuel.
• Strong, rust and corrosion-resistant galvanized steel frame – The durable structure of the tank ensures that contaminants won’t be able to enter through weak spots or cracks. 
• 110% double-walled containment – The in-built double-walled containment eliminates the need for drip trays. Secondary containment that’s left out in the elements may collect water where microbial contamination may be more likely. 

Browse our range of tanks to find the perfect solution for your fuel storage needs.