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NFPA 490-2002
NFPA 490: Code for the Storage of Ammonium Nitrate, 2002 Edition
Applies to the storage of ammonium nitrate in the form of crystals, flakes, grains or prills, including fertilizer grade, dynamite grade, nitrous oxide grade, technical grade and other mixtures containing 60 percent or more ammonium nitrate by weight, but does not apply to blasting agents.
National Fire Protection Association [nfpa]