minimizing back pressure in a tank

[NEplantengineer]

I've got a tank accepting both compressed air and wastewater at the same time. I need to keep the static pressure in the tank at or below 1" WG (i.e. atmospheric) by selecting the appropriate size vent. I've done a calculation assuming that the developed static pressure in the tank equals the frictial losses from the flow of air up and out of the vent. Anyone else run into this kind of problem?

 

[Montemayor]

hoconnor:

I've never run into this kind of problem because I've anticipated that I would have to size the vent nozzle such that it could handle the evacuated & displaced air inside the tank. The losses aren't just frictional; there is contraction and expansion taking place. You say you've done the calculations; what are your results - on paper and actual? Can you share the results with us?

Art Montemayor
Spring, TX