Ethanol is a colorless, volatile liquid used widely as a solvent, a fuel source, and a component in blended fuels. As a flammable liquid, an ethanol fire presents distinct hazards that make common extinguishing methods, particularly using water, extremely dangerous. Successfully controlling an ethanol fire depends entirely on understanding its specific characteristics and employing the correct tools and techniques.
Characteristics of Ethanol Fires
Ethanol fires pose a particular challenge because the flame is often nearly invisible, especially in bright daylight. The clean-burning nature of ethanol produces a smokeless, blue flame that lacks the luminous glow typically associated with combustion. This invisibility can lead to severe burn injuries if a person is unaware the fire is still burning or attempts to refuel a seemingly extinguished source.
Ethanol is a polar solvent, meaning it is water-miscible and mixes readily with water. This characteristic is important because standard firefighting techniques for Class B fires often involve applying water or traditional foam. Since ethanol mixes with water, a stream of plain water can dilute the fuel but will also spread the burning liquid, potentially enlarging the fire area. This water-miscibility also causes traditional firefighting foams to break down and become ineffective.
Initial Steps and Safety Warnings
Upon discovering an ethanol fire, the first step is to prioritize human safety and immediately assess the scale of the incident. If the fire is large, rapidly spreading, or blocks the only escape route, evacuation is necessary. Emergency services must be called immediately, and you should never attempt to fight a fire that is too large to manage safely.
Plain water should never be used on a burning ethanol spill or container. Using a straight stream of water can scatter the burning liquid, causing the fire to spread rapidly. If the fire involves an appliance or a small pool of liquid, attempt to stop the fuel source or contain the spill only if it is possible to do so without risk.
Before attempting extinguishment, confirm the presence of the flame, even if it is not immediately visible. This can be done by carefully using an object, such as a broom handle, to locate the heat column or the invisible blue flame. This confirmation prevents the mistake of assuming the fire is out when only the visible portion has been suppressed.
Approved Extinguishing Methods and Tools
For small ethanol fires, such as those contained within a bioethanol fireplace or a small spill, the safest approach is to smother the flame to cut off the oxygen supply. Many home appliances come with a specific metal snuffer or damper tool designed to extinguish the flame. Non-flammable materials like a fire blanket, sand, or baking soda can also be used to cover and smother a small, contained spill.
For larger fires or spills that require mechanical suppression, specific types of fire extinguishers are required. Dry chemical extinguishers rated for Class B fires, such as ABC or BC types, can be effective by interrupting the chemical reaction. When using a dry chemical extinguisher, the agent should be applied in a sweeping motion aimed at the base of the flames. Take care not to spray directly into the liquid, which could cause the burning ethanol to splash. Carbon dioxide (CO2) extinguishers are also suitable for small- to medium-sized fires as they displace oxygen, but they offer no cooling effect, and the fire can re-ignite if the fuel is still hot.
The most effective agent for controlling and suppressing large ethanol spills is Alcohol-Resistant Aqueous Film-Forming Foam, or AR-AFFF. Unlike standard AFFF, AR-AFFF contains polymeric thickeners specifically formulated to resist breakdown by polar solvents like ethanol. When applied, this specialized foam creates a cohesive, protective blanket over the liquid surface. This barrier serves a dual purpose: it separates the flammable vapor from the oxygen in the air, and it prevents the ethanol from destroying the foam, ensuring the blanket remains stable to prevent re-ignition.
Preventing Ethanol Fires
Minimizing the risk of an ethanol fire starts with safe storage and careful handling of the liquid fuel. Ethanol containers should always be stored in a cool, dry, and well-ventilated area, away from direct sunlight, heat sources, or any potential ignition sources. Proper ventilation is important because ethanol vapor is denser than air and can settle in low areas, potentially creating an ignitable atmosphere.
Refueling procedures require strict adherence to safety guidelines to prevent accidental ignition. Ethanol should never be poured onto a lit fire or into a burner that is still warm. A cooling period of at least 30 minutes is often required after a flame has been extinguished before attempting to add more fuel. Additionally, all flammable materials, such as curtains or furnishings, should be kept at a safe distance from any device burning ethanol.