Uic Class U Special Wagon (Paperback)

High Quality Content by WIKIPEDIA articles! The International Union of Railways groups all special classes of railway goods wagon (less those in classes F, H, L, S or Z) into Class U in its goods wagon classification system. The powder wagon is a special form of bulk goods wagon designed to transport goods in powder form. These wagons are pneumatically unloaded, usually by using compressed air. For goods that might react with oxygen in the compressed air, nitrogen is used instead. These wagons are used for bulk commodities, such as cement, that are so fine-grained they cannot be poured, or at least do not pour very well, and so cannot be emptied under gravity. Under the UIC system they are given the Class letter U and supplementary letter c. The do not normally have their own compressors but must be unloaded using external equipment.