Although it does not exist in Spanish, it is used by influence of English rather than the correct flammable form ("which can be lit with fire") . The problem is not in flame ( "flame, fire") but in the prefix in- which in addition to "in , inside, content" also means "missing, removes"; that's why some misunderstand flammable as inflatable ("no flame, no fire").
as well they commented before the word flammable, it concerns combustible materials that need heat to reach the point of ignition ( burn ) they must exceed 38 degrees to light. the flammable below its ignition point 38 degrees reason whereby you do not need to be heated as up to 40 static electricity; generated by friction ) they could catch fire, this due here generated their own gases or vapours and although they said are more dangerous since if there is air scatters it and if you find a point of ignition long distance would return flame or flame-shaped up to place your storage
Adj. It can easily burn ( and cause an explosion violent ). It comes from the Latin noun "flamma": calls, and the ending 'able': capable of. Synonym: flammable. May seem contradictory, flammable and flammable are equivalent, because in this case the preposition 'in' is not negative. Inside, means that there is a principle - property possibility to generate flames inside. Pure Spanish is flammable. The use of flammable is under the influence of English, notwithstanding that in this language there is also the 'inflammable' diction, but - by custodial misinterpretation of 'in'-, preferably 'flammable' has been used.