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Explanation using Bernoulli's equation

Bernoulli's equation may be applied to a siphon to derive its ideal flow rate and theoretical maximum height.

Bernoulli's equation:

Apply Bernoulli's equation to the surface of the upper reservoir. The surface is technically falling as the upper reservoir is being drained. However, for this example we will assume the reservoir to be infinite and the velocity of the surface may be set to zero. Furthermore, the pressure at both the surface and the exit point C is atmospheric pressure. Thus:

Apply Bernoulli's equation to point A at the start of the siphon tube in the upper reservoir where P = P, v = v and y = − d

Apply Bernoulli's equation to point B at the intermediate high point of the siphon tube where P = P, v = v and y = h

Apply Bernoulli's equation to point C where the siphon empties. Where v = v and y = − h. Furthermore, the pressure at the exit point is atmospheric pressure. Thus: