Flash Back 3 : When a trail of flammable material (usually solvent vapor) is ignited by a distant ignition source and the flame travels back to the fuel source
W. A. N Dorland and E. J. Taylor (editors), Glossary of MSDS Terms, Texas A&M University, USA 2001. http://www.bio.tamu.edu/USERS/TONNA/GLOSSARY.HTM, (MSDS - Amer) {631}