Siphon

siphon (sī`fən, –fŏn), tube through which a liquid is lifted over an elevation by the pressure of the atmosphere and is then emptied at a lower level. To start the siphon, it must first be filled with the liquid before it is placed into position. The elevation over which a siphon will lift a liquid is limited by the atmospheric pressure. At sea level, water may be lifted c.34 ft (10.4 m). The siphon must discharge at a level lower than that of the liquid at the intake.

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siphon, syphon

1. a tube placed with one end at a certain level in a vessel of liquid and the other end outside the vessel below this level, so that atmospheric pressure forces the liquid through the tube and out of the vessel

2. See soda siphon

3. Zoology any of various tubular organs in different aquatic animals, such as molluscs and elasmobranch fishes, through which a fluid, esp water, passes

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siphon [′sī·fən]

(botany)

A tubular element in various algae.

(engineering)

A tube, pipe, or hose through which a liquid can be moved from a higher to a lower level by atmospheric pressure forcing it up the shorter leg while the weight of the liquid in the longer leg causes continuous downward flow.

(geology)

A passage in a cave system that connects with a water trap.

(invertebrate zoology)

A tubular structure for intake or output of water in bivalves and other mollusks.

The sucking-type of proboscis in many arthropods.

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Siphon 

a bent tube with legs of different lengths, through which a liquid flows from a vessel at a higher leveito a vessel at a lower level (see Figure 1). In order to start the operation, the siphon must first be filled with the liquid. The action of a siphon results from the fact that the pressure on the liquid volume filling the upper (hatched) section of the siphon applied from the direction of the upper reservoir, that is, from the left, is higher than that applied from the direction of the lower reservoir, that is, from the right. Thus, at the moment when the flow starts, the pressure on the left is equal to p₀− γh¹ and the pressure on the right is equal to p₀ - γh₂, where γ is the specific weight of the liquid, p₀ is the pressure on the free surface of the liquid, and h₂ > h₁. In this manner, when the liquid is flowing

Figure 1. Diagram of the operation of a siphon

through the siphon, a pressure is established in the upper section that is lower than p₀. The greater the difference in the heights h₂ - h₁ and the greater the liquid’s energy loss in overcoming the resistance of the tube, the greater the pressure drop in the upper section. This circumstance limits the difference in the heights of the liquid and, consequently, the operation of the siphon; when the pressure in the flow is below a certain limit, the column of liquid is disrupted. When cold water at atmospheric pressure is being transferred by a siphon, the maximum difference in the heights is usually no more than 6 to 7 m.