Follow this link http://www.iapws.org/ it should answer most of your questions.
Also two guys from Cambridge did alot of early work in this area, search under Keenan and Keyes for more perhaps historical info.
Good luck!
Having flammable liquids in an a pipe does not automatically classify the area as hazzardous. If that were the case then my house which has uses hydrocarbons (#2 Fuel Oil and Propane) would be classified as hazzardous.
Consult the National Electrical Code for definition of when an area is...
