Diesel Fuel Tank Water Removal

Diesel truck driving with water tank.

If water is present in a diesel fuel tank, it can lead to serious problems. That’s why checking for water and removing it as soon as possible is important for every diesel fuel storage system. Excess water is common in diesel fuel because of condensation and environmental conditions. Water can get into fuel tanks year-round and can affect the quality of the fuel. Regularly removing water from diesel fuel tanks is a crucial part of the maintenance process.

How Does Water Get into Your Diesel Fuel Storage Tank?

Condensation is one of the main ways water can be introduced to the tank and fuel line. Diesel fuel actually absorbs the water that is in the air and biodiesel absorbs even more water than standard fuel. When a fuel tank cools off after use, humid air can fill up the tank and cause condensation on the tank walls. In areas where the temperature fluctuates between high humidity and cooler temperatures, fuel storage tanks may experience more incidences of condensation.

Temperature fluctuations can also occur with diesel fuel and tank equipment. When warm diesel fuel enters a cool tank, additional moisture may build up as the diesel cools off. This is common in diesel fuel tanks and can be managed when the water is drained periodically. Diesel fuel stored above ground is more affected by temperature changes than fuel stored underground. Fuel is less dense than water, so the water will sink to the bottom of the tank.

Water can also get into storage tanks through human error, like if a storage drum is left out in the open when it rains. If the diesel tanks have faulty seals then humid air and water can get inside. Poor fuel handling procedures can also lead to water accumulating in the fuel tank. For vehicles it is best to top off the fuel tanks before parking them at night, this reduces the amount of warm moist air in the tanks.

Why Is Water in a Fuel Storage Tank Bad?

Water is considered a contaminant to your fuel system and can lead to rust, corrosion, a clog in the filtration system, and broken fuel injectors. While all fuel contains small amounts of water, too much water contamination can cause serious problems throughout the entire system. If too much water is in the diesel fuel it can look hazy and dark.

When water is left in diesel for too long, bacteria and microorganisms can start to grow in this moist environment. These types of microbial growth will produce a layer of slime that can end up clogging filters. Bacteria can also move through the entire fuel system and cause corrosion and damage to various components. Microbes can be hard to remove from a fuel system so they should be addressed immediately.

Storage tanks for fuel are typically made with steel and iron, which can rust with exposure to water. When rust builds up, it can lead to clogged fuel filters and even affect the fuel injectors. If water and other contaminants make it to the fuel injectors, it can cause premature wear, corrosion, and metal parts to stick together.

Diesel engines depend on fuel to function as a lubricant, and water can negatively affect lubrication in the engine. When water isn’t removed efficiently, the fuel pump and injector can be damaged, which affects the efficiency of the engine.

How to Remove Water from a Fuel Tank

The first step to removing water from a fuel tank is to test the fuel for water. You can extract a small amount of the fuel by hand with a bilge pump. Let the fuel sit in a clear container and in a dark place for about 24 hours. Water is denser than diesel, so if it is present then it will sink to the bottom of the container. A thin black layer between the water and fuel separation is also a sign that there are microbes in the fuel too.

If you determine there is water in the tank that needs to be removed, allow time for the fuel to settle without being moved or shaken. Then you can utilize the fuel-water separators to drain off any water that has accumulated. You may also need to use an appropriate pump with an extended hose to reach the bottom of the tank where water accumulates. When microbes are present in the fuel, you may need to add commercial biocide to the fuel. Keep in mind these microbes may well be present in your equipment that fuels from the storage tanks and the biocide will also kill microbes in the equipment.

For large storage tanks and underground fuel storage, draining water can be more challenging. There are companies that provide maintenance services for fuel storage that can effectively remove water and contaminants from a fuel tank. This may include using fuel additives that involve emulsifying or demulsifying. An emulsifier will combine the water with the fuel, while a demulsifier will separate the water from the fuel so it sinks to the bottom.

Preventing Water Problems in a Fuel Tank

It may be impossible to avoid water entering the fuel tank, but you can be better prepared for when it does happen. The best way to prevent water problems in a fuel tank or storage system is by removing water accumulation as soon as possible. Here are a few ways you can be proactive and prevent water from causing serious problems.

Keep diesel fuel tanks topped off whenever possible

This helps prevent humid air from accumulating in the tank at night. When there is space in the tank at night, a cooling tank and humid air can cause condensation to form.

Set a schedule for checking water

A typical recommendation may be to check for water accumulation once a month. However, this rule of thumb may need to be adjusted based on your fuel tanks and storage systems in place. Checking for water should be a relatively simple process and done as often as possible.

Determine the water limit for the fuel tank

A small amount of water may always be present in a tank, so the safe range of water will depend on the size of the fuel tank or storage tank. Decide what amount of water depth will signal that it is time to drain water based on the size and manufacturer recommendations.

Minimize the loss of fuel during water draining

When you drain water from a tank, it is possible to lose some level of fuel as well. There are many options available to maximize the amount of fuel that stays in the tank. Additives and absorbing treatments can address small amounts of water left over.

Remember: More water, more problems

When in doubt, drain the water. The more water that accumulates in the fuel tank and storage system over time, the more problems you will likely encounter down the line. Water damage can result in costly repairs that could have been prevented by addressing water accumulation more frequently and in smaller amounts.



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