Many types of foam burn rapidly. Some even drip burning material on to the surface below, helping a fire spread rapidly. However, there are foams formulated to provide high levels of fire resistance. Whenever possible these should be used near potential sources of ignition.
The fire-resistance of foam for use in appliances, enclosures and equipment is measured by testing to procedures set out in the UL94 standard. (Note: this does NOT address foam used in upholstery or building construction.) Flammability (the ease with which a material burns,) is shown by a UL94 rating, such as the UL94 V-0 indication carried by PORON® 4701-V0-M.
Anything composed of carbon and hydrogen will burn if conditions are right, and that means having oxygen and an ignition source. All foams are formed from these elements and oxygen is always present in the atmosphere, so to start a fire all that's needed is an ignition source. This could be provided by an electrical spark, such as when motors or relays produce arcing. High temperatures, as caused by friction between moving parts or electrical current flowing through wiring are others possible causes.
UL94 flammability ratings
The UL organization is an independent global testing organization dedicated to improving safety. Founded in 1894 as "Underwriters Electrical Bureau" it started out by testing noncombustible insulation material and grew to become first "Underwriters Laboratories" and now just UL.