Suction Pump

A suction pump raises liquid by creating a partial vacuum inside a cylinder, most often by drawing a piston upward inside it, so that the greater atmospheric pressure pressing down on the liquid's open surface pushes the liquid up into the pump chamber to fill the space the piston leaves behind; a valve then lets the liquid pass upward past the piston while blocking it from flowing back down on the piston's return stroke. Dual-action suction pumps, which pump on both the up and down strokes of the piston through a pair of valves, have been found among the ruins of Pompeii, showing the mechanism was already known to Roman engineers. The Arab engineer Ismail al-Jazari described dual-action suction pumps as part of larger water-raising machines in the thirteenth century, and the design reappeared in medieval Europe from around the fifteenth century onward, remaining the standard means of lifting water by hand or animal power until Otto von Guericke's development of the true vacuum pump in 1650 opened the way to more powerful mechanical pumping.