You may have noticed fuel tanker trucks with a metal chain hanging from the back and wondered what it is for. It might look like a simple piece of equipment, but the chain is connected to an important safety principle: controlling static electricity around flammable fuel.
As a tanker moves along the road, friction between the vehicle, tires, air, and other surfaces can create static electrical charges. Loading and transporting fuel can also contribute to static buildup. Under the wrong conditions, a spark could become a serious ignition hazard.
The hanging chain is traditionally intended to provide a path for electrical charge to dissipate toward the ground. By keeping the vehicle electrically connected with its surroundings, it can help reduce the accumulation of static
