Often a drum may be referred to as a barrel.  The two common sub-types of drums are the open head and tight head.  Open head drums are sealed with a lid and ring clamp.  Tight head drums have two 2” ports in the top, one NPT and the other buttress thread.  Typically, tight head drums are best suited for liquid products, but open head drums can be used for dry, or powdered products, which are often bagged.  Drums have top and bottom ridges which sufficiently strengthens them so that they can be turned on their sides and rolled. Drums most often are manufactured in blue or translucent (near-white), but sometimes come in other colors also, usually for recognition of containing specialized products.

30-gallon drum
29” tall, 19” diameter
Empty weight: approximately 12 lbs
Weight filled with water: approximately 263 lbs

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55-gallon drum
35” tall, 24” diameter
Empty weight: approximately 22 lbs
Weight filled with water: approximately 481 lbs