siphon, syphon (noun)

a tube running from the liquid in a vessel to a lower level outside the vessel so that atmospheric pressure forces the liquid through the tube

siphon, syphon (verb)

a tubular organ in an aquatic animal (especially in mollusks) through which water can be taken in or expelled

siphon, syphon, siphon off (verb)

convey, draw off, or empty by or as if by a siphon

siphon (verb)

move a liquid from one container into another by means of a siphon or a siphoning action

"siphon gas into the tank"

siphon (Noun)

A bent pipe or tube with one end lower than the other, in which hydrostatic pressure exerted due to the force of gravity moves liquid from one reservoir to another.

siphon (Noun)

a soda siphon

siphon (Noun)

a tubelike organ found in animals or elongated cell found in plants.

siphon (Verb)

to transfer (liquid) by means of a siphon.

Siphon

The word siphon is sometimes used to refer to a wide variety of devices that involve the flow of liquids through tubes – see siphon terminology – but in the narrower sense it refers specifically to a tube in an inverted U shape which causes a liquid to flow uphill, above the surface of the reservoir, without pumps, powered by the fall of the liquid as it flows down the tube under the pull of gravity, and is discharged at a level lower than the surface of the reservoir it came from. Note that while the siphon must touch the liquid in the reservoir, it need not touch the liquid in the lower reservoir and indeed there need not be a lower reservoir – liquid can discharge into mid-air. In practical siphons, atmospheric pressure pushes the liquid up the tube into the region of reduced pressure at the top of the tube in the same way as a barometer, and indeed the maximum height of a siphon is the same as the height of a barometer, because they operate by the same mechanism. The reduced pressure is caused by liquid falling on the exit side. When both ends of a siphon are at atmospheric pressure, liquid flows from high to low. However, if the lower end is pressurized, liquid can flow from low to high, as in siphon coffee. While in everyday siphons, atmospheric pressure is the driving mechanism, in specialized circumstances other mechanisms can work – in the laboratory, some siphons have been demonstrated to work in a vacuum – see vacuum siphons – indicating the tensile strength of the liquid is contributing to the operation of siphons at very low pressures. Most familiar siphons have water as a fluid, though mercury is often used in experiments, and other fluids such as organic liquids or even carbon dioxide can be siphoned.

Siphon

A siphon (from Ancient Greek: σίφων, romanized: síphōn, "pipe, tube", also spelled nonetymologically syphon) is any of a wide variety of devices that involve the flow of liquids through tubes. In a narrower sense, the word refers particularly to a tube in an inverted "U" shape, which causes a liquid to flow upward, above the surface of a reservoir, with no pump, but powered by the fall of the liquid as it flows down the tube under the pull of gravity, then discharging at a level lower than the surface of the reservoir from which it came. There are two leading theories about how siphons cause liquid to flow uphill, against gravity, without being pumped, and powered only by gravity. The traditional theory for centuries was that gravity pulling the liquid down on the exit side of the siphon resulted in reduced pressure at the top of the siphon. Then atmospheric pressure was able to push the liquid from the upper reservoir, up into the reduced pressure at the top of the siphon, like in a barometer or drinking straw, and then over. However, it has been demonstrated that siphons can operate in a vacuum and to heights exceeding the barometric height of the liquid. Consequently, the cohesion tension theory of siphon operation has been advocated, where the liquid is pulled over the siphon in a way similar to the chain fountain. It need not be one theory or the other that is correct, but rather both theories may be correct in different circumstances of ambient pressure. The atmospheric pressure with gravity theory obviously cannot explain siphons in vacuum, where there is no significant atmospheric pressure. But the cohesion tension with gravity theory cannot explain CO2 gas siphons, siphons working despite bubbles, and the flying droplet siphon, where gases do not exert significant pulling forces, and liquids not in contact cannot exert a cohesive tension force. All known published theories in modern times recognize Bernoulli’s equation as a decent approximation to idealized, friction-free siphon operation.