Work out separator sizing instantly with clear inputs, formula shown and shareable results.
A two-phase separator must hold the liquid for long enough to release entrained gas — typically 1-3 minutes for oil, longer for foaming or viscous crude. Holdup volume is liquid rate converted to cubic feet per minute times retention time; the vessel is then sized with a length-to-diameter ratio of about 3 to 4.
Liquid holdup
Holdup volume (ft3) = liquid rate (bbl/d) x 5.6146 / 1440 x retention time (min)
Vessel geometry
Size the shell for the holdup volume at a length-to-diameter ratio of 3 to 4
Pressure vessel design, sizing and relief protection must comply with the applicable pressure vessel code and be certified by a qualified engineer.
The Souders-Brown droplet settling criterion, which limits gas velocity so that liquid droplets fall out rather than being carried over. It scales with the square root of the density difference.
Foam occupies vessel volume without separating, so retention time must be multiplied — often by two to four — or a foam-breaking internal fitted.