UN 1011 — Butane

Butane, also known as n-butane, is a colorless gas with a faint petroleum-like or natural gas odor. It is classified as a DOT Class 2 gas and is extremely flammable. Butane is used in a variety of industrial applications, including as a fuel for vehicles, heating, and cooking. First responders may encounter butane in various scenarios, including transportation accidents, leaks, or fires. The scale of production and transport of butane is significant, with millions of tons being transported every year. Butane is also used in residential and commercial settings, making it a common substance that first responders may encounter. The widespread use of butane increases the likelihood of first responders encountering it in emergency situations.

Hazard overview: Butane is extremely flammable and will be easily ignited by heat, sparks, or flames. It will form explosive mixtures with air, and vapors from liquefied gas are initially heavier than air and spread along the ground. Vapors may travel to the source of ignition and flash back, posing a significant risk to first responders. The LC50 value for butane is not well-established, but it is known to be toxic in high concentrations. The IDLH value for butane is 21,000 ppm. Butane is also an asphyxiant and can displace oxygen in confined spaces, leading to respiratory distress or even death. In a worst-case scenario, a large butane leak or fire can lead to a significant explosion, posing a risk to first responders and the public.

Response guidance: In the event of a butane leak or fire, first responders should isolate the area 100m in all directions initially and evacuate 800m downwind if it is a large spill. If a tank or rail car is involved in a fire, first responders should isolate the area 1600m in all directions and consider evacuation. The correct suppression agent for butane fires is dry chemical, CO2, or water spray for cooling containers only. Foam is not typically required for gas fires. First responders should also contact CHEMTREC for guidance on responding to butane incidents. Decontamination procedures should be followed to prevent the spread of butane vapors. Evacuation zones should be established based on the size of the spill or fire and the wind direction.

Firefighter training notes: First responders should be trained on the hazards of butane and the correct response procedures, including isolation distances, suppression agents, and decontamination procedures. A common tactical error when responding to butane incidents is underestimating the risk of explosion. ICS positions, such as the incident commander and safety officer, should be aware of the hazards of butane and ensure that first responders are properly trained and equipped. Mutual aid criteria should include the availability of butane-specific response equipment and trained personnel.

Regulatory context: Butane is classified as a DOT Class 2 gas and has a packing group of II. The OSHA PEL for butane is 800 ppm, and the TLV is 800 ppm. Butane is not listed on the CERCLA list, but it is regulated by the EPA under the Clean Air Act.

Storage & handling: Butane should be stored in well-ventilated areas, away from incompatible materials such as chlorine and fluorine. The temperature limit for butane storage is -40C (-40F), and the container type should be designed for liquefied compressed gas. Incompatible materials for butane include oxidizers, such as chlorine and fluorine, and other flammable gases.