U.S. fire departments respond to an estimated average of 10,500 structural fires in industry and manufacturing properties per year, according to the National Fire Protection Association (NFPA). These fires result in an average of 12 civilian deaths, 300 civilian injuries and $509 million in direct property damage, per year. The NFPA reports that in as many as 10 percent of those fires, the first item to ignite was a flammable or combustible liquid or gas, filter or piping.
Flammable and combustible liquids are used by virtually every industry in the world - medical, food processing, automotive, shipping, chemical, manufacturing, construction, sanitation, environmental and many more. Such liquids require special fire safety measures throughout their manufacture, processing, transportation, use and storage. As indicated by the NFPA’s statistics, improper handling of flammable liquids can pose serious safety risks and cause costly property damage. Undoubtedly, many of the fires reported by the NFPA could have been prevented or reduced in scope had flammable or combustible items been properly stored in approved flammable storage containers.
To encourage proper use and storage of flammable liquids, many industries and product manufacturers have independently developed their own guidelines for specific materials. However, OSHA maintains official regulation over flammable liquid storage in the U.S. In addition to OSHA, the NFPA is an excellent resource, providing recommended guidelines for flammable and combustible liquid storage.
Both OSHA and NFPA classify burnable liquids into two categories: combustible and flammable. The flashpoint and boiling point determine the class of a liquid. (The “flashpoint” of a liquid is the minimum temperature at which a liquid gives off vapor within a test vessel in sufficient concentration to form an ignitable mixture with air near the surface of the liquid.)
Combustible liquids are defined as any liquid having a flashpoint at or above 100° F (37.8° C). Combustible liquids are then divided into two sub-categories. Class II liquids are combustibles with flashpoints at or above 100° F (37.8° C) and below 140° F (60° C), while Class III liquids are those with flashpoints at or above 140° F (60° C). Common examples of combustible liquids include paint thinner, home heating oils, motor oils, cooking oils, lubricating oils and diesel fuel.
Flammable liquids, also known as Class I liquids, are liquids that have a flashpoint below 100° F (37.8° C). Class I liquids are further divided into three subcategories. Class IA liquids have flashpoints below 73° F (22.8° C) and having a boiling point below 100° F (37.8° C). Class IB liquids have flashpoints below 73° F (22.8° C) and having a boiling point at or above 100° F (37.8° C). Class IC liquids have flashpoints at or above 73° F (22.8° C) and below 100° (37.8° C). Common examples of flammable liquids include styrene, acetone, benzene, toluene, hydrazine, some paints and solvent-based cements, motor and aviation gasolines, lacquers and lacquer thinner and some light crude oils. Class I liquids may be used only where there are no open flames or other sources of ignition within the possible path of vapor travel.