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Managing Moisture in Fuel Tanks

farmer inspecting outdoor fuel tanks

Keep storage tanks clean and dry to ensure quality fuel is available for your diesel engines. Moisture in fuel causes all sorts of issues that can lead to unplanned downtime and equipment failure.

Ideally, we would like our fuels to be free of water, but small amounts will always be present. Diesel fuel will hold small amounts of water in suspension. “Suspended” water passes through with the fuel and is essentially “invisible” to the fuel system causing no damage. 

However, when enough water is present it can no longer be in suspension, we get “free” water. Unchecked free water can lead to microbial growth, fuel line freeze-ups, biodegradation of fuel, and fuel tank corrosion. Worse yet, water and associated contaminants can plug filters. This can lead to more serious problems within the engine, such as fuel injector failures.

The most common way water enters a fuel tank is through condensation. Temperature differences from inside and outside the tank cause water to form in the headspace of the tank. This causes moisture droplets to “sweat” down into the fuel.

Preventing Moisture in Fuel Tanks

The best way to minimize the risk of moisture-related problems is to follow good fuel-quality management practices. Useful techniques include reducing condensation, using filters, regular tank maintenance and using high-quality diesel fuel. 

Reduce Condensation

You can minimize temperature differentials by providing shade for the storage tank. Painting the tank white can also help reduce condensation and fuel evaporation, especially during warm temperatures. A Pre-Vent® Fuel Cap can help reduce condensation, too. 

For tanks on equipment, filling at the end of the day helps to normalize fuel temperatures. It also eliminates headspace which leads to less condensation as temperatures drop overnight.

Use and Check Filters

We recommend the use of Hydrosorb® filters as they absorb a small amount of water as it passes through with the fuel. When the filter captures a significant amount of water, it prematurely plugs. This helps detect a possible larger water problem. 

These filters not only help to detect water, but also fine particles associated with moisture. This can include microbial growth and rust resulting from tank corrosion. Filters plugged with contaminants associated with corrosion can be a tell-tale sign of water or particle contamination problems within the tank.

Inspect Tanks Regularly

Follow-up inspections and regular tank maintenance can help ensure that only dry fuel reaches your equipment. Inspect tanks regularly to detect water and contamination before they cause other issues. Pull a sample from the bottom of your tank (not through the nozzle as the fuel is already filtered) and check that it is still clear and bright. 

Hazy fuel is an indication that water is building up. Darker than normal color is an indication of microbial growth or fuel beginning to break down through oxidation. Particulates can be rust, dirt, pollen, and more. Remember that water and contamination problems can happen in transfer and equipment tanks, too.

Use High-Quality Diesel Fuel

Purchasing a high-quality diesel fuel such as Dieselex® Gold helps control moisture in fuel tanks. Unique moisture-control chemistry helps by encapsulating a larger amount of water within the fuel. This allows it to pass through the filter and fuel system without causing harm, keeping tanks dry for longer periods.

Dieselex Gold also includes demulsifier chemistry that causes “free” moisture to drop to the bottom of the fuel tank for physical removal. Corrosion inhibitors help protect any metal exposed to moisture from corroding too quickly. Operators have more time to identify and remove water before it becomes a bigger problem.

If you suspect water problems, your local FS Energy Specialist can assist you with inspecting and resolving issues within your fuel tank. Call your FS Energy Specialist to discuss potential solutions today.

Pre-Vent® and Hydrosorb® are registered trademarks of Central Illinois Manufacturing Company.

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