An airlift is device based on a pipe, used in

nautical archaeology Maritime archaeology (also known as marine archaeology) is a discipline within archaeology as a whole that specifically studies human interaction with the sea, lakes and rivers through the study of associated physical remains, be they vessels, s ...

to suck small objects, sand and mud from the

sea bed The seabed (also known as the seafloor, sea floor, ocean floor, and ocean bottom) is the bottom of the ocean. All floors of the ocean are known as 'seabeds'. The structure of the seabed of the global ocean is governed by plate tectonics. Most of ...

and to transport the resulting debris upwards and away from its source. It is sometimes called a suction dredge. A water dredge or

water eductor A water eductor or water dredge is an eductor-jet pump-based tool used by underwater archaeologists to remove sediments from an underwater archaeological site. Airlifts may be used for the same purpose. It consists of a large bore straight tube ...

may be used for the same purpose. Typically, the airlift is constructed from a 3-metre to 10 metre long, 10 cm diameter pipe. A controllable compressed air supply vents into the inside, lower end of the pipe (The input end always being the lower end). Compressed air is injected into the pipe in one to three second bursts with an interval long enough to let the resulting bubble to rise to the higher, output end of the pipe. The bubble moves water through the pipe sucking debris from the lower end and depositing it from the upper end of the pipe. Ejected debris can be either cast off (as in simply removing

overburden In mining, overburden (also called waste or spoil) is the material that lies above an area that lends itself to economical exploitation, such as the rock, soil, and ecosystem that lies above a coal seam or ore body. Overburden is distinct from tai ...

) or collected in a mesh cage for inspection (as more often is the case in nautical archaeology). It is often designed to be hand-operated by a diver.

Airlift pump An airlift pump is a pump that has low suction and moderate discharge of liquid and entrained solids. The pump injects compressed air at the bottom of the discharge pipe which is immersed in the liquid. The compressed air mixes with the liquid c ...

s are used by water utilities, farmers and others to extract water from deep wells. In such cases the pipes can be 30, 60 or more meters deep underground. Airlift pumps are governed by the physics of

two-phase flow In fluid mechanics, two-phase flow is a flow of gas and liquid — a particular example of multiphase flow. Two-phase flow can occur in various forms, such as flows transitioning from pure liquid to vapor as a result of external heating, separ ...

References

{{Underwater diving, prodiv Underwater work equipment ru:Эрлифт

See also

References