Flammable Materials

Flammable and Combustible Liquids

Flammable and combustible liquids vaporize and form flammable mixtures with air when in open containers, when leaks occur, or when heated. To control these potential hazards, several properties of these materials, such as volatility, flashpoint, flammable range and autoignition temperatures must be understood.  Information on the properties of a specific liquid can be found in that liquid’s safety data sheet (SDS), or other reference material.

Flammable Aerosols

Flammable liquids in pressurized containers may rupture and aerosolize when exposed to heat, creating a highly flammable vapor cloud. As with flammable liquids, these should be stored in a flammable storage cabinet.

Flammable and Combustible Solids

Flammable solids often encountered in the laboratory include alkali metals, magnesium metal, metallic hydrides, some organometallic compounds, and sulfur. Many flammable solids react with water and cannot be extinguished with conventional dry chemical or carbon dioxide extinguishers. See Anecdotes for descriptions of incidents involving such materials.

  • Ensure Class D extinguishers, e.g., Met-L-X, are available where flammable solids are used or stored.
  • Sand can usually be used to smother a fire involving flammable solids. Keep a container of sand near the work area.
  • If a flammable, water-reactive solid is spilled onto skin, brush off as much as possible, then flush with copious amounts of water.
  • NEVER use a carbon dioxide fire extinguisher for fires involving lithium aluminum hydride (LAH). LAH reacts explosively with carbon dioxide.

Catalyst Ignition

Some hydrogenated catalysts, such as palladium, platinum oxide, and Raney nickel, when recovered from hydrogenation reactions, may become saturated with hydrogen and present a fire or explosion hazard.

  • Carefully filter the catalyst.
  • Do not allow the filter cake to become dry.
  • Place the funnel containing moist catalyst into a water bath immediately.

Purge gases, such as nitrogen or argon, may be used so that the catalyst can be filtered and handled in an inert atmosphere.


Stanley Howell
Sr. Program Manager
Chemical Safety

Steve Elwood
Associate Director for Laboratory Safety