Downpipe for a tank

[Vnctt]

Hi. I am looking for info in terms of how a downpipe works in a tank. I have a tank with slurry that is continuously being filled e.g. 50m3/h and also pumping away at same rate. now we have installed air distribution at the bottom that creates fine bubbles, these bubble then carry protein with them as they rise, its more like foaming this slurry. the foam rest on top of the slurry. what we do to remove the foam, is we run the level of tank high so that the foam can overflow. problem is the density of the slurry changes affecting the level control(level is controlled using a pressure transmitter at the bottom. So with this level fluctuations, end up flooding on top and pushing too much slurry with foam or not overflowing foam because level is low.
Someone hinted on putting a downpipe that will allow the foam to overflow while keeping the level in the tank.

Does anyone has ideas about how a downpipe works in a tank etc.

[allen_wong]

have same problem in F&B process,
want to know what is downpipe too.

Maybe you can try using the ball float valve to control the level

[JAlberts]

In your case it would be a drain pipe with its top opening at the desired level of the tank. One modification of this that might help to minimize the loss of foam going into the drain pipe would be to fit the top of the pipe with a loose fitting cap with its bottom edge extending below the the top of the pipe that would allow the fluid to flow through the annulus between the pipe and cap and a gap between the top of the pipe and the inside top of the cap.