Gas, Class 4 Unstable Reactive 4 : Materials that in themselves are readily capable of detonation or explosive decomposition or explosive reaction at normal temperatures and pressures
NFPA 55 Standard for the Storage, Use, and Handling of Compressed Gases and Cryogenic Fluids in Portable and Stationary Containers, Cylinders, and Tanks, 2005 ed. http://www.nfpa.org/assets/files/AboutTheCodes/55/ TIA55-05-1.pdf, http://www.colorado.edu/firelifesafety/sites/defau lt/files/attached-files/gas_storage.pdf, (Std: Storage, Use, and Hndlg of Compressed Gas and Cryogenic Fluids in Portable and Stnry Conts, Cylinders, and Tnk - Amer) {211 NFC}