With these definitions in mind it is possible to divide ignitable materials into
four major classes. A flammable solid is one that can ignite from friction or from
heat remaining from its manufacture, or which may cause a serious hazard if ignited.
Explosive materials are not included in this classification. A flammable liquid is
one having a flash point below 60.5°C (141°F). A combustible liquid has a flash
point in excess of 60.5°C, but below 93.3°C (200°F). Where gases are substances
that exist entirely in the gaseous phase at 0°C and 1 atm pressure, a flammable
compressed gas meets specified criteria for lower flammability limit, flammability
range (see below), and flame projection.