The San Carlos Fire Department has responded to fires that have ignited because of spontaneous combustion with oil soaked rags. As the weather gets better, many homeowners wish to stain decks and fences to beautify their homes. The applicators used to spread the stains left in a closed container can become a safety nightmare.  Many people do not believe it can happen.  For no apparent reason, fire erupts, usually during off hours – as the materials have had time to react. This is called spontaneous ignition, and preventing is part of your job. 

Spontaneous ignition occurs when a combustible object is heated to its ignition temperature by a chemical reaction involving the oxygen in the air around us.  This “oxidation “process creates heat that, if not dissipated, will build up until ignition occurs.  Generally, this can happen when the materials are left in piles and the heat being generated in the pile cannot be released into the air. 

A number of materials are moderately or highly subject to spontaneous heating and subsequent ignition.  Some of those you may find in your work area include oil based paint in contact with cotton or other fibrous combustible material; Cloth material that is damp with any one of a number of different types of oils, including vegetable oils;uniforms or work clothes with paint over spray, which are all possible coming fromflammable liquids. 

The possibility of spontaneous ignition is great if the surrounding air is also warm and dry.  The added heat, say from nearby machinery or a non-insulated steam line, can either pre-heat the material, which in turn sets off the reaction, or can hasten ignition by adding even more heat to the combustible. 

It is simple to prevent spontaneous ignition, since oxygen is needed for it to occur. Materials subject to spontaneous ignition should be stored in covered metal containers such as a rag safety can or a metal trashcan.  Admittedly the container will contain oxygen at first.  However, the oxidation process will cease and reaction will stop the fires ignition. 

Another strategy is to spread the combustible material out so the resulting heat can be dissipated rather than allowed to build up-again, fire prevented. 

Good housekeeping is the key to preventing fires. Remove all debris from around the home.  Properly store flammable and combustibles liquids in covered metal containers.  Be sure the containers remain in place away from electrical appliances and other ignition sources.  Fires do not only damage buildings, but they threaten the lives of those living in the home, as well as the firefighters fighting the fires