Hand pumps are manually operated pumps; they use human power and mechanical advantage to move fluids from one place to another. They are widely used in for a variety of industrial, marine, irrigation and leisure activities. There are many different types of hand pump available, mainly operating on a piston, diaphragm or rotary vane principle with a check valve on the entry and exit ports to the chamber operating in opposing directions. Most hand pumps have sliding vanes, diaphragms, plungers or pistons, and are positive displacement. They include drum and barrel pumps, hydrostatic test pumps, diaphragm and piston bilge pumps, pitcher pumps, diaphragm priming pumps and manual sewage pumps.