Safety Bulletin

Instructions To Minimize The Risk of Fire From Static Electricity In Special Gasoline Fueling Situations-- Those Not Involving The Direct Fueling of Cars and Trucks

News about a fire at a service station recently was published on the Internet:

"I want to relate an incident that happened to a friend of mine the other day. He was filling a small gas can placed on the bedliner in the back of his pickup. The gasoline spontaneously ignited, burning him in the process. The investigation determined that the fire was caused by static electricity."

Gasoline fires suspected of being started by a spark of static electricity during fuel transfer are rare. Almost none of the documented incidents involve direct fueling of a car or truck because both vehicles and dispensers are designed to dissipate static electricity to ground. Instead, they involve fueling situations where the gasoline receptacle could be insulated from ground-portable containers and equipment being transported on a truck or trailer.

Portable Containers

To minimize the danger from fire while filling a portable container with gasoline...

Other general safety considerations

The above instructions also apply to rack-mounted, five-gallon, military-type fuel containers, which should be removed from the vehicle and placed on the ground for filling; and to portable containers used as fuel reservoirs for outboard marine engines, which should be removed from the boat and placed on the ground or on the wharf for filling.

Equipment on Trucks or Trailers

Motorcycles, lawn movers and other garden equipment, snowmobiles, jet skis and boats are examples of gasoline-powered equipment that are transported on trucks and trailers. Because Chevron is aware of three fires involving jet skis and snow-mobiles, we suggest, when practical, either:

Customers who choose to fuel gasoline-powered equipment on a truck or trailer directly from a dispenser should make sure they keep the dispenser nozzle in contact with the fuel tank fill tube.

Gasoline, Static Electricity And Fires

Gasoline has a low electrical conductivity-- it does not conduct electricity very well. As a result, a charge of static electricity builds up on gasoline as it flows through a pipe or hose and this charge takes several seconds to several minutes to dissipate after the gasoline has reached a tank or container. If this charge discharges as a spark from a tank or container to the grounded metal nozzle of the gasoline dispenser hose, it may ignite the gasoline. Ignition requires that the spark occur near the tank opening where the gasoline vapor is in the flammable range.1 A spark discharge directly from the surface of the gasoline to the grounded nozzle also is possible. Normally, this will not result in ignition because the concentration of gasoline vapor near the liquid is above the flammable limit.

Theory and experience suggest that the condition most likely to lead to a spark discharge is filling a metal container or tank that is insulated from ground, i.e., one which is ungrounded. This is the situation that exists when a metal container is placed on a plastic bedliner.

Most Hazardous Ungrounded metal container
Less Hazardous Non-conducting container
(e.g., plastic container)
Least Hazardous Grounded metal container

The Petroleum Equipment Institute recorded 25 fires involving the filling of portable gasoline containers between 1990 and 1995. Appendix I summarizes the conditions of the 20 incidents for which they have first-hand reports. The frequency of incidents increased in 1994 and 1995, perhaps because bedliners became more common in this period.

Preventing Static Electricity from Initiating Gasoline Fires

Fires initiated by sparks can be prevented if static electricity is not allowed to build up, particularly on conductors. One defense is to dissipate electrical charge by creating paths that allow it to flow to ground.

Placing a container on the ground makes it easier for electrical charge to escape. Cement or dirt are better conductors of electricity than asphalt and, therefore, better grounding surfaces. While vehicles that are driven to a service station may not appear to be grounded, they are. Tires are good enough conductors to allow electrical charge to escape to ground.

Keeping the dispenser nozzle in contact with the container at the inlet or with the fuel tank fill tube creates another path by which electrical charge can escape. This is because the dispenser is grounded and the nozzle is bonded to the dispenser through the dispenser hose.

When a vehicle or other equipment can't be placed on the ground, a second defense is to fuel more slowly. The slower gasoline flows, the less static electricity is generated. This is why Chevron suggests using a portable container to fuel gasoline-powered equipment (motorcycles, jet skis, snowmobiles, lawn mowers, etc.) being transported on a truck or trailer. People usually pour fuel more slowly from a portable container than it is delivered by a dispenser.

As one of several actions to warn customers, Chevron is posting this warning label on Chevron gasoline dispensers:

WARNING: PORTABLE CONTAINER FIRE HAZARD
Improper filling of portable gasoline containers creates danger of fire.

To fill a container:

  • Place approved container on the ground away from vehicle or trailer. DO NOT fill any container that is inside a vehicle or on a truck/trailer bed.
  • Keep nozzle in contact with the container while filling. Do not use a nozzle lock-open device.

It is unlawful and dangerous to dispense gasoline into unapproved or improperly labeled containers.

Other Safety Information about Containers

Approved Containers. Federal, state, and local regulations make it unlawful to dispense gasoline into unapproved or improperly labeled containers. To be approved, a container must be predominantly red in color and must be able to hold gasoline securely without risk of leaking or breaking. Glass containers are not approved for transporting or storing gasoline. The container also must bear a warning label about the dangers of gasoline. Approved containers made of metal or plastic are available at hardware and automotive supply stores.

A container with acceptable strength and durability can be made from either metal or plastic when properly designed and manufactured. Metal containers, when grounded, provide the greatest protection against fires caused by static electricity. Plastic containers will not rust or corrode when gasoline is stored in them for a long time.

Several organizations have developed standards for portable gasoline containers, including the American Society for Testing and Materials (ASTM)2, Underwriters Laboratories (UL)3 and the Canadian Standards Association (CSA)4.

Underwriters Laboratories and the Canadian Standards Association have programs to certify that commercial portable gasoline containers meet the specifications of one or more of the above standards. Containers certified by Underwriters Laboratories bear the familiar UL symbol. Underwriters Laboratories certifies plastic portable gasoline containers and metal and plastic portable gasoline safety containers. It does not certify regular metal gasoline cans. The standard which Underwriters Laboratories uses for certification is designated by the manufacturer and is indicated on the container. Some containers currently being sold were certified against ASTM D 3435. These are still approved containers even though this standard has been discontinued.

The Commonwealth of Massachusetts used to require that portable containers sold in the state be approved by the state fire marshal. Massachusetts has discontinued its approval program and now accepts the certification of recognized testing laboratories. However, some commercial containers still carry Massachusetts' approval statement.

In addition to the ASTM performance standards for portable gasoline containers, there is a voluntary ASTM labeling standard6. It recommends that the label contain this information:

DANGER
GASOLINE
EXTREMELY FLAMMABLE
VAPORS CAN EXPLODE
HARMFUL OR FATAL IF SWALLOWED

  • If swallowed, do not induce vomiting, call physician immediately
  • Keep out of reach of children
  • Avoid prolonged breathing of vapors
  • Do not siphon by mouth
  • Do not store in vehicle or living space
  • Store and use in well-ventilated area
  • Vapors can be ignited by a spark or flame source many feet away
  • Keep away from flame, pilot lights, stoves, heaters, electric motors and other sources of ignition
  • Keep container closed

All labels on commercial portable containers may not use this exact wording, but they all communicate the same basic warnings.

Used Containers. Make sure that a used container is an approved container and that it is properly labeled. Used containers should be inspected before reuse. The inside should be free of dirt and debris and the cap should form a tight seal capable of preventing the escape of either vapor or liquid. Metal containers should be free of corrosion. Plastic containers should be free of stress cracks.

Container Location. At a service station, consumers should be aware of their surroundings when deciding where to place a portable container on the ground for filling. For instance, the location should be out of the path of other vehicles, and other people should be warned away while the container is being filled.

Chevron recommends that the filling location be a safe distance from the consumer's vehicle and other vehicles because engines that have just been turned off have hot surfaces (exhaust manifold and catalytic convertor) that could ignite gasoline vapor. Gasoline vapor, which is invisible and heavier than air, can flow along the pavement for some distance when not dispersed by air currents. If ignited, the vapor becomes a fuse that brings the flame back to the liquid gasoline source. The distance that is "safe" depends on the conditions, but Chevron believes placing the container about five feet from an ignition source usually should be sufficient.

Filling Procedure. Because portable containers are much smaller than vehicle fuel tanks, they fill a lot faster. To prevent over-filling or a spill, the customer needs to control fuel flow, which is why Chevron recommends against locking the nozzle trigger-valve open while filling a portable container.

The container should be filled only 95% full. The remaining air space allows room for the gasoline to expand if it warms up later. Otherwise, expansion could force liquid gasoline out of the container or distort the container.

In many areas, gasoline nozzles are equipped with an accordion-like sleeve to reduce emissions of gasoline vapor during fueling. The sleeve helps return the vapor in the vehicle's tank to the service station's tank. The sleeve must be compressed to activate the nozzle. When fueling a vehicle, this happens naturally when the nozzle is inserted into the filler spout. The same procedure isn't practical with a container inserting the nozzle into the inlet far enough to compress the sleeve will activate the nozzle's shut-off mechanism when the container is only partially full. Chevron recommends that a customer compress the sleeve with one hand while controlling the nozzle valve with the other. This procedure allows the customer to see that the nozzle remains in contact with the container. It also allows the customer to monitor the rising fuel level and to stop at the appropriate time.

Transportation. Before putting a container of gasoline in the trunk of a vehicle or the bed of a pickup or truck, tighten the cap of the container and the cap of the air vent, if there is one. Wipe the outside of the container to remove any liquid gasoline or gasoline residue. Secure the container in the trunk or pickup so turns or road vibrations won't cause it to slide around or tip over. Do not leave a container of gasoline in direct sun, or in the trunk of a car that is in direct sun. Heating the gasoline will build up pressure in the container.

Storage. The Uniform Fire Code only approves one- and two-gallon metal or plastic containers for the indoor storage of Class I-A flammable liquids, the class to which gasoline belongs. Furthermore, the Code states that the quantity of gasoline stored in approved containers in private garages or other approved locations shall only be the amount necessary for maintenance purposes and operation of equipment and shall not exceed 10 gallons, unless it is stored in a storage cabinet designed for flammable liquids, in which case the limit is 30 gallons.

General Safety Information about Gasoline

Gasoline is dangerous. First, and foremost, it is extremely flammable. Gasoline ignites easily and burns vigorously. Gasoline vapor may explode. Second, exposure to gasoline liquid or vapor can adversely affect health.

To minimize the danger of fire while transferring gasoline...

Avoid breathing gasoline fumes.

For both fire and health reasons, it is best to handle gasoline outdoors. Ignition sources are less prevalent and the fumes are diluted and dispersed more quickly.

Chevron's Material Safety Data Sheet (MSDS) for gasoline provides this overview of the product's hazards:

The MSDS provides detailed information on the hazards associated with gasoline and the appropriate responses. A customer may obtain an MSDS for Chevron gasoline by calling (800) 689-3998.

Appendix 1

Nature and Frequency of Gasoline Fires Involving Portable Containers Which Are Suspected To Have Been Started by Static Electricity

The Petroleum Equipment Institute7 knows of 25 fires involving the filling of portable gasoline containers between 1990 and 1995. Most of them occurred in 1994 and 1995. Here is the breakdown of the 20 fires for which they have first-hand reports.

Number
of Incidents		Type
of Container		Location of Container
12 Metal On plastic-lined bed of pickup truck
1 Metal On carpeted bed of pickup truck
1 Metal On carpeted floor of automobile
4 Plastic On plastic-lined bed of pickup truck
1 Plastic Removed from plastic-lined bed of pickup truck and placed on pavement
1 Plastic Pail On pavement

Footnotes


1 Gasoline vapor can be ignited only when its concentration in air is between 1.4 and 7.6 percent by volume. At lower concentrations there is too little vapor for ignition and at higher concentrations there is too little air (oxygen) for ignition.


2 American Society of Testing and Materials, 100 Barr Harbor Drive, West Conshohocken, PA 19428; (610) 832-9585.


3 Underwriters Laboratories, Inc., 333 Pfingsten Road, Northbrook, IL 60062; (847) 272-8800.


4 Canadian Standards Association, 178 Rexdale Blvd., Toronto, ON M9W1R3; (416) 747-4000.


5 Portable safety containers have a pour spout with a spring-activated lid.


6 ASTM F 839 - Standard Specification for Cautionary Labeling of Portable Gasoline Containers for Consumer Use.


7 Petroleum Equipment Institute, P.O. Box 2380, Tulsa, Oklahoma 74101; (918) 494-9696.

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