Barrel pumps are used in barrels and drums and are sometimes referred to as barrel pumps or container pumps. Drum pumps are generally available as 55-gallon barrels but they are also used in 5, 15, 30, 55, 275 and 330-gallon containers. They are available in many forms, from simple rotary-style to a variety of other styles like the lever, siphon, double diaphragm, electric, air, piston, etc. Drum pumps contain a vertical shaft within a slender tube which is inserted within the drum gap. The pump motor is hooked up to the vertical shaft at the highest of the tube outside on top of the drum and the pumping component is also found at the top of the shaft within the drum. This configuration permits the drum to be empty and reduces the chance of spills and operator injury.