Static Electricity at the Gas Pump Can Spark a Fire
Auburn, Nov. 11, 2003 --- Have you noticed the signs on gas pumps about the dangers of static electricity while refueling your car? These warnings are not a gimmick. Static electricity can spark a fire or explosion so consumers need to be careful and heed the warnings.
Static electricity is an electric charge caused by an imbalance of electrons on the surface of a material. It is most commonly caused by the contact and separation of materials. The area of contact, the speed of the separation, relative humidity and other factors determine the amount of charge created. One example of this is a person walking across a carpeted floor. Static electricity is generated as the shoe soles contact and separate from the carpet.
“Static electricity can build up when a person exits and re-enters a vehicle, particularly in cool or cold and dry conditions,” said Dr. Jesse LaPrade, an Extension environmental specialist.
“When you exit and re-enter your vehicle while refueling, there is the potential for sufficient static electricity to build up that a spark can discharge between your body and the fuel nozzle. In rare circumstances, the spark can ignite gasoline vapors around the fill spout, causing a brief flash fire,“ LaPrade said.
Once vapors ignite, the fire will continue until the fuel supply is shut off. In most cases, damage and injuries are minor, but serious personal injury and major property damage may occur when the fuel supply from the dispenser is not stopped.
In most cases, when people pull into a gas station to refuel a vehicle, they open the car door, slide out of the seat, open the fuel pipe cover of the vehicle, touch the nozzle on the gas pump, and perhaps touch the pump to use a credit card--all before they insert the nozzle into the fill pipe. Any static charge that was picked up in the car is dissipated several times.
A new static charge can be picked up if you get back into the car after the refueling has started. The synthetic material of the car seats and clothing add to the possibility of picking up a static charge. If you don’t touch metal before returning to the nozzle and fuel pipe, that static charge can be transferred when you touch the nozzle, thus creating the potential for a flash fire.
According to the Petroleum Equipment Institute there are three causes of static electricity fires at gas pumps:
- 50 percent are caused when a person returns to a vehicle during refueling and doesn’t shut the door or touch other metal when leaving the car to remove gas pump nozzle from the car’s fuel pipe.
- 29 percent are caused when a person unscrews the gas cap.
- 21 percent occur for other reasons.
There are several theories about why static fires at gas pumps are increasing. One is the almost universal switch to self-serve pumps, which requires millions of people who are unfamiliar with the volatility of gasoline to handle it once or twice a week.
Also, today’s vehicles have more electronics--CD players, geopositioning systems, satellite radios, cruise control, on-board diagnostics and electronically controlled fuel injection. Those elements combined with nylon seat covers could create more static.
Other theories include the use of cold weather-formulated fuels that are more volatile, tires made with less carbon and more silica, having fill pipe cover releases inside the vehicles and automobile parts made of dissimilar materials such as plastic and metal.
LaPrade said if people will follow the following safety guidelines when refueling, they will reduce the chance for sparking a fire.
- Always turn off your vehicle engine while refueling.
- Stay near the vehicle fueling point during the process.
- Never smoke, light matches or use lighters while refueling.
- Don’t get back into the vehicle while refueling--even when using the nozzle’s automatic hold-open latch. If you must re-enter the vehicle, discharge static electricity build up when you get out by touching the outside metal portion of the vehicle, away from the filling point, before attempting to remove the nozzle.
- Don’t overfill or top off your tank. The fuel dispenser will shut off automatically when the tank is full.
SOURCE: Dr. Jesse LarPrade, Extension Environmental Specialist, Alabama Cooperative Extension System
University at Buffalo
Environment, Health & Safety Services
Gas Pump Fire Safety
Gasoline fumes are highly flammable and will readily ignite when they find an ignition source. In this video (QuickTime Player required, download here) the customer is able to lock the gasoline pump handle on so that fuel continues to flow while she returns to the vehicle. Notice that she slides back and forth on the seat several times as she checks progress, creating a static electric charge. It is this static electric charge that produces a spark when she touches the nozzle and ignites gasoline fumes around her gas tank fill tube. She was lucky and was not injured, but she could just as easily been seriously burned. Her reaction to the fire is even more dangerous, as she shuts off the nozzle and tries to blow out the flames. She should have simply went directly to the station attendant and had him or her turn off electrical power to the pump, using their emergency pump shut-off switch.
In New YorkState gasoline retailers are required to disable the locking device on their pump nozzles, making it necessary to hold the nozzle handle open. This reduces the possibility of a static charge developing and causing gasoline fumes to ignite, but does not eliminate the possibility of a fire. If a customer were to release the handle, leave it in place while returning to the vehicle and then come back to the nozzle without touching a metal surface a static arc could be discharged.
The safest way to avoid developing a static charge that could result in a fire is to be sure that you touch metal on your vehicle, before you begin fueling or restart fueling if you go back to your vehicle for any reason.
Static Electricity and Gas Pump Fires
By: Constance Harness
Todd C. Frankel, of Charleston Daily Mail (), reported on the danger static elecrticity presents at the gas pump.
On November 3, 1999, Robert Sexton and his wife Emma had dinner at the Ponderosa restaurant in Huntington. They then dropped their newborn daughter Brittney by a relative's house and took U.S. 60 toward LincolnCounty to visit Emma's parents. They stopped for gas on the way at SuperAmerica station just out of Huntington. Robert inserted the pump nozzle into his white Toyota Camry; and, because it was chilly, locked the nozzle in the open position and jumped back into the car. In his side-view mirror, he saw a woman waving her arms. The gasoline was overflowing from the tank. He jumped out of the car and reached for the nozzle.
He sparked a fire and was ignited when he simply touched the gas pump nozzle. He was not smoking. The engine was off. He was not using his cell phone. He received third-degree burns on 20 percent of his body, mostly his legs and arms. He spent two weeks in the burn unit at CabellHuntingtonHospital and another two months out of work. The state fire marshal's office concluded that the fire was likely caused by static electricity.
Static electricity is usually not dangerous but when combined with gasoline vapors at the fuel tank opening, a small spark can cause a fiery explosion. The public remains almost entirely unaware that this may occur. Gas stations have been reluctant to post signs at the pumps warning that static electricity can ignite gasoline vapors. Speedway (formerly known as SuperAmerica) gas stations are the exception; they post signs which read: "Static Electricity Spark Explosion Hazard. Do Not Get Back Into Your Vehicle While Refueling. Re-entry Could Cause Static Electricity Build Up."
The German Society for Petroleum and Coal Science and Technology concluded in their comprehensive 1997study that: "When persons leave their vehicles' seats, they can become electrostatically charged and remain charged for some time. Electrical discharge by individuals in proximity to escaping fuel vapors can create a hazard."
In Broken Bow, Nebraska, on January 3, 2000, a man suddenly caught fire while refueling his Ford F-150 pickup. Luckily, he suffered only minor injuries. The fire started when he reached to remove the nozzle from his pickup. He noticed a spark fly from his hand to the nozzle.