ASME-Landmark:Archimedes Screw Pump

The wind-driven Archimedes screw-pump was used to recover salt through an age-old process of solar evaporation, which shifted brine from one salt concentrating pond to the one of next higher salinity. The screw-pump preserved in California represents a mechanically simple method used for more than a century in the San Francisco Bay Area, from about 1820 to 1930.

The Archimedes screw consists of a screw inside a hollow pipe. The screw is turned by a windmill or manual labor—in California's case, by a windmill—and as the shaft turns, the bottom end scoops up a volume of water. This water is then pushed up the tube by the rotating helicoid until finally it pours out from the top of the tube.

Archimedes screws do not require a perfectly watertight surface between the screw and the pipe, as long as the amount of water scooped with each turn is greater than the amount of water leaking out of each section of the screw per turn. If water from one section leaks into the next lower one, it will be continue to travel upwards by the next segment of the screw.

The screw-pump concept is attributed to mathematician and inventor Archimedes (287-212 BCE). The design of the windmill drive on the pump shaft originated in Holland before 1600. Andrew Oliver, who founded the Oliver Salt Company (absorbed by the Leslie Salt Company in 1936), designed this version of the wind-driven Archimedes screw-pump. It was restored to working condition by Donald Holmquist. See ASME website for more information