I believe Gerry Hurst was finally able to get him to admit in the Georgia "Sheila Bryan" litigation (see below), that in some rare cases he did get such ignition to occur.
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I heard from several longtime friends that it was a rare event but in seminars Ralph was able to duplicate ignition of gasoline by hot surface when the spray bottle was in more of a stream mode than spray.
2017 NFPA 921 in the Appendix also cites:
2.3.3 API Publications. American Petroleum Institute, 1220 L
Street, NW, Washington, DC 20005-4070.
...
API RP 2216, Ignition Risk of Hydrocarbon Vapors by Hot Surfaces
in the Open Air, 3rd edition, 2003, reaffirmed 2010.