Gases or mixtures of gases having an absolute pressure exceeding 40 psi at 70F; or an absolute pressure exceeding 104 psi at 130oF, regardless of the pressure at 70 F; or liquids having a vapor pressure exceeding 40 psi at 100oF
University of Maine, Department of Chemistry, Glossary of Safety Terms and Acronyms, Orono, ME, USA 2009. http://www.business.govt.nz/worksafe/tools-resourc es/glossary-of-terms-and-acronyms/a-to-b, (ChemSfty - Amer) {503}