As used in this part, the following definitions apply:
(1) "Anhydrous ammonia" means a compound formed by a combination of two gaseous elements, nitrogen and hydrogen, in the proportion of one part nitrogen to three parts hydrogen by volume, which compound is in either gaseous or liquid form and is used primarily as fertilizer.
(2) "Anhydrous ammonia facility" or "facility" means any building, tank, or system of equipment used for processing, storing, or distributing anhydrous ammonia and includes all appurtenances to such building, tank, or system.