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Clean Diesel Best Practices

Keep Diesel Clean and Dry 

Dirt, water and other contaminants cause damage to equipment, tanks, and diesel fuel itself. Rather than try to fix problems after they cost you time and money, develop preventive programs to avoid these problems to begin with. Following the below best practices for fuel storage will help prevent the expense and downtime that can be caused by contaminated diesel fuel.

Delivered Fuel Quality 

Fuel suppliers should be expected, at a minimum, to provide diesel that meets industry specifications and is compatible with the local climate. It is reasonable to ask your distributor to provide certification that the fuel meets or exceeds ASTM D975 requirements and applicable ASTM appendices (or your local equivalent). 

Diesel users should develop a periodic testing procedure to monitor the quality and cleanliness of incoming diesel. It may be difficult to refuse a delivery of much needed fuel, but it is far easier to isolate quality problems upstream than it is to fix them after they contaminate your storage tanks and are spread throughout your fleet. Many reputable fuel distributors will help you with this process, or even do it on your behalf. 

Tank Farm Design and Maintenance 

A good diesel fuel storage design takes into account both stability and cleanliness issues: 

Ensure drainability: Make sure there is a low point in your tank where water and contaminants will logically accumulate and can be conveniently removed. This can be accomplished by selecting a tank with a built-in sump, or installing your tank at a slight angle so that natural accumulation occurs near the low-point drain. A typical low point drain will be several inches/centimeters above the tank bottom, so if the tank is not installed at an angle, there will always be a relatively large volume of fluid below the drain point that cannot be easily removed. Both horizontal and vertical tanks can hold significant water. 

Don't use the tank bottom: It is generally a good idea to keep the fuel level high. The bottom of the tank contains all the water and contaminants that have settled out of the fuel. This portion of the tank should never be allowed to become high enough that it is dispensed into your equipment. Position the outlet pipe at an adequate height or install a floating suction device to avoid this. 

Avoid temperature extremes: Heat accelerates fuel degradation and promotes microbial growth. Cold contributes to the formation of free water and leads to precipitation of soft, waxy solids. Installing the tank in the shade of a protective awning or applying a reflective paint can help prevent extreme heat. Underground tanks maintain a more moderate temperature both summer and winter, but are banned in certain areas due to ground water contamination concerns. Tank heaters are generally cost prohibitive. 

Turnover fuel frequently: Fuel should be turned over as rapidly as possible, at least every three months is recommended. No fuel should be kept in storage for over 12 months. Very frequent turnover is encouraged in the presence of high temperatures or biodiesel, both of which contribute to accelerated fuel degradation. 

Prevent ingress: It is surprising how much dirt and water can enter a tank through simple ingress. All reasonable measures should be taken to ensure that there are no structural leaks and that all seals are tight in order to protect the fuel from ground water, rain and pressure washing. In addition, breather pipes should be protected with combination desiccant/air filters. As fuel is dispensed, outside air is drawn into the tank, along with dirt and moisture. More information below. 

Monitor fuel quality: Periodic testing is recommended to detect fuel instability, contamination issues and the presence of free water. Free water must be drained regularly. Fuel and tank cleaning should be undertaken promptly as indicated by your test results.

Bulk Fuel Filtration

Removing contaminants with bulk filtration prior to pumping diesel into equipment allows onboard filtration systems to do their job better, while supporting the advanced fuel system technology required to meet emissions standards. 


A good single pass filtration system on the inlet of the bulk storage tank reduces the risk of introducing contamination into your fuel storage infrastructure and helps maintain desired cleanliness levels. The diesel in your tank represents a significant investment. Why risk contaminating it by receiving a load of fuel with excessive levels of dirt, water, soft solids or bugs? Stop contamination before it stops you. Protect your tanks, your fuel, and your equipment by refusing entry to harmful contaminants. Donaldson bulk filtration systems can be sized for any application. Small systems can be just as efficient as large, more complex systems, if designed correctly.


Protect your diesel investment while it is in your bulk storage tank. Install T.R.A.P. (Thermally Reactive Advanced Protection) desiccant breathers with integrated high efficiency air filtration. These breather filters reduce the risk of moisture and contaminants entering the bulk storage tank from the vent so that fluids are kept clean and dry. When moisture is a known problem, the addition of an Active Reservoir Vent (ARV) blows a blanket of dry air over fuel in storage to reduce the fluid's relative humidity. It draws moisture from the fuel with dry compressed air to remove dissolved, free, and emulsified water from the fuel.


Clean fuel one last time just before it enters the equipment. Point of use filters polish or remove any contaminants that may have been picked up in storage or during final transfer. This is the most critical place to filter, as it is the last safeguard before the fuel passes into your equipment.

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