If you already know the size of the separator (and the weir height etc. then you will find the residence time by deviding the volume in the sep. by the volume flow of the phae.

But i suspect that what you are looking for is the required size - not the given? API and GPSA has guidelines. I think its API 12J but i dont have the std. here for checking. The equations are generally relating to Navier Stokes law re. terminal settling velocity.

Best regards

Morten

Morten,
Are you sure the equations relate to "Navier Stokes" not "Stokes Law"? Navier Stokes has zero practical applications as postulated. People have carved off pieces and assumed stuff out of existence as special cases that have been amazingly useful, but the basic Navier Stokes equation is pretty non-practical.

David Simpson, PE
MuleShoe Engineering

"Belief" is the acceptance of an hypotheses in the absence of data.
"Prejudice" is having an opinion not supported by the preponderance of the data.
"Knowledge" is only found through the accumulation and analysis of data.

Got me David I didt find the refernces myself and may remember incorrectly. The part about the terminal (or ultimate?) Setteling velocity of water (or oil) droplets in oil (or water), that im fairly certain of.

But i seem to recall that Campbell also states some "good starting point"