4 replies to this topic

[ramnath]

hey guys
this question was asked during an interview to a candidate.
" transfer liquid from tank A to Tank B thru gravity transfer method"
the rules are
no electrical/electronic/elctro-mechanical accessories should be used
at any point of time during the flow the velocity[flow rate ] should be constant.

expecting the replies
ramnath

[billya]

I take it raising the height of tank A is to simple.

[pinku]

Hi Dave,

The Pressure head is converted in to velocity factor when we keep one tank one above the other. Here the mass flowrate is constant ie

Q= Velocity x area x density.

As the level of water decreases the velocity factor decrease to have a constant Q , Area has to be increased hence there should be a converging pipe from tankA to tankA.

[djack77494]

In order to hold the velocity and the flowrate constant, necessarily the driving force must be kept constant. Except for the trivial answer of zero flow, when you transfer the liquid, the only way I can imagine this being true is when the vessel being emtied is much larger than the vessel being filled. Then changes in the emptying vessel could be neglected. Still, in order to ignore changes in the filling vessel, it should be below the emptying vessel so that its level has no impact.

If you relax the gravity flow requirement, you can achieve the other requirements with a pressure transfer.

Is there a correct answer to this puzzle?
Doug