University of Vermont

Cultivating Healthy Communities

Be Aware of Risks When Refueling

Since 2010 the U.S. Environmental Protection Agency has required that all diesel fuel produced in the United States be Ultra Low Sulfur Diesel. ULSD plus cleaner-burning diesel engines helps to improve air quality by significantly reducing emissions. However, farmers, construction companies and other businesses with on-site diesel fuel tanks need to be aware of potential risks.

ULSD poses a greater static ignition hazard than earlier diesel formulations with higher sulfur content. This means an increased risk of fire or explosion if the entire system used to refuel your equipment (fuel supply tank, transfer pump, transfer hose, nozzle and other components) is not properly grounded and bonded.

At one time, diesel fuel had about 5,000 parts per million (ppm) sulfur. Then came Low Sulfur Diesel at 500 ppm sulfur. ULSD is 15 ppm. It is now the only diesel fuel available in North America. Other countries are following our lead.

By removing the sulfur and other compounds in ULSD, its conductivity is decreased and its ability to store a static electricity charge increases. Refineries have added a static-dissipating additive, but its effectiveness is reduced over time and by passing through filters as it makes its way to your fuel storage tank. Static charges can build up as the fuel flows though the fuel delivery system.

Diesel fuel is not as combustible as gasoline, but it is nearly as combustible. When static electricity discharge occurs with combustible vapors present, a fire or explosion may result while you are fueling your vehicle or equipment.

Any fire or explosion would cause flaming fuel to come back out the filler neck onto the person fueling the equipment. This has happened, with tragic results, which is why it is so important to make sure that the entire system used to refuel your equipment is properly grounded and bonded.

A properly grounded fuel delivery system has an electrically conductive connection from the fuel delivery tank system to earth ground to allow static and electrical charge dissipation. Your vehicle, with its rubber tires, is pretty well grounded.

Do you have a bed liner in your pickup truck?  If you answered yes, then that fuel tank in the bed of your truck is NOT GROUNDED.  It needs to be bolted directly to the truck to be grounded.

A properly bonded fuel delivery system has an electrically conductive and unbroken connection between all components. A wire connection from the fuel delivery system to the equipment chassis will equalize the static electric potential between the two machines, reducing the chance of a static electric discharge. If you have jumper cables in your truck, they will suffice for bonding.

Stay put while refueling the equipment. If you are walking around, you could be building a static charge. Touch the body of the truck to dissipate any static build up before touching the fueling system.

If you are unsure about how well your system is grounded or have questions about bonding, contact your fuel supplier to request a check of your system.

Ultra Low Sulfur Diesel is here, now. It has dangers its predecessors didn't so you need to learn how to handle it safely. Don't take any shortcuts to bonding and grounding while refueling to save time. It could be deadly.

For more information, refer to the Association of Equipment Manufacturers' bulletin at