What is an Archimedes Screw?

An Archimedes screw is a device which is designed to lift liquids from one level to another. Put in simpler terms, it's a pump. This device is one of the earliest mechanical pumps invented by humans, and it continues to be use in some regions of the world today. Variations on the basic design can also be utilized for solids such as ashes and grain. The topic of the Archimedes screw is often covered in science classes when students are introduced to devices developed by people who lived in ancient times and needed to solve basic engineering problems.

This device is named for its purported inventor, Archimedes, who lived in the third century BCE. Archimedes is also credited with developing a number of other interesting devices, including the burning mirror, a device used in military conflict to set fire to distant ships. The Archimedes screw was widely used all over the Mediterranean within decades of its invention, and the design spread to other regions of the globe as traders and merchants exchanged information about regional inventions they encountered.

Classically, the Archimedes screw consists of a cylinder with a screw mounted inside, although the design can also be inverted, with a cylinder serving as a base for a spiral shaped tube. To use the device, it is mounted at a 45 degree angle, and turned. As the screw turns, it scoops up a small amount of water, and the water is carried up the Archimedes screw with the movement of the screw, eventually flowing out of the top of the cylinder or coil.

This design can be used in a variety of ways. Historically, it was extremely useful for irrigation, as the design allowed people to move water from lower levels to higher areas, and it permitted farmers and others to move water around as needed. The Archimedes screw has also classically been used in land reclamation and drainage, and in fact they continue to be used for this purpose in damp regions of the world like the Netherlands.

Grain elevators utilize the basic principle of the Archimedes screw, and people also use these devices in sewage treatment plants. Because sewage often contains a mixture of solids and an assortment of textures, regular pumps are not always up to the task, and they can fail. An Archimedes screw is capable of lifting sewage dependably, regardless as to the rate of flow or consistency. For people who have wondered what's inside the large angled pipes at most sewage treatment plants, the answer is probably an Archimedes screw.