Flash point, by definition, is “the temperature to which a fuel must be heated to produce a fuel/air concentration sufficient to ignite when exposed to open flame.” The flash point of crude oil determines its flammability. Crude with a flash point above 140 degrees is combustible; crude with a flash point below 140 degrees is flammable.
Undiluted San Ardo crude, light enough to flow without blending, is transported as a “combustible” because its flash point is above 140 degrees.
Crude transported from the Alberta tar sands, through our communities, is blended 20 to 30 percent with flammable diluents so it’s fluid enough to load into rail cars (source: Railway Age, rail industry safety publication http://www.railwayage.com).
The ignitability of crude blended with flammable diluents is now determined by the most volatile component, turning combustible product into a flammable liquid.
A regulatory exemption allows a shipper to reclassify and ship a flammable liquid as a less-expensive combustible liquid. How safe is transporting a flammable liquid in a combustible-liquid tank car?
Derailments nearly always result in leakage and a source of ignition, providing all elements necessary for fire and explosion.
Are you in the blast zone?