All,
Is butadiene subject to NFPA 58? It seems to me that it is a gray area:
1. Defn. of LPG from the standard: “3.3.43* Liquefied Petroleum Gas (LP-Gas). Any material having a vapor pressure not exceeding that allowed for commercial propane that is composed predominantly of the following hydrocarbons, either by themselves (except propylene) or as mixtures: propane, propylene, butane (normal butane or isobutane), and butylenes.”
a. I would submit that Butadiene is a butylene (2 double bonds, instead of 1).
But perhaps the intention of the standard was not to include butadienes in butylenes?