One of the factors that influences when designing the diameter of a filling
column is the velocity of circulation of both flows (gas and liquid) that turn out to be
tolerable through the bed filling.

Thus, in a column that contains a certain filler, served by a defined liquid
flow, the velocity of the gas has an upper limit that is known as velocity of flooding.
The velocity of flooding can be obtained by starting from the relation between the
pressure drop throughout the filling bed and the flow of gas.

Что такое "Drag flow and velocity of flooding"?

Осторожно: текст - перевод с испанского на английский, поэтому может возникнуть несовместимость теминов.