Static Electricity at the Gas Pump Can Spark a Fire
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
“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
“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,“
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
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
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
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
in MS Word