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API 12J Interactive Tools
Live calculator · Separator visual · Step-by-step · Common mistakes
Select mist eliminator — sets K-factor
0.35
Wire mesh pad
0.40
Vane pack
0.18
No eliminator
0.50
Cyclonic
MMSCFD
psig
°F
— (air=1)
lb/ft³
Results — Souders-Brown Method
Gas density ρG—lb/ft³
Compressibility Z—
K-factor selected0.35
Vmax (Souders-Brown)—ft/s
Q actual at operating conditions—ACFS
Min. internal diameter
—“
Standard NPS →
—
Preliminary sizing only — apply 10–15% project design margin. Sour service: confirm mist eliminator material meets NACE MR0175.
Tap a zone to see what happens inside the vessel
① Gas space
Clean dry gas exits here
Vmax applies here. Gas velocity must stay below the Souders-Brown limit or liquid re-entrains into the gas outlet line.
② Mist eliminator
K-factor lives here
Wire mesh (K=0.35), vane pack (K=0.40), none (K=0.18). Your K selection drives the entire vessel diameter calculation.
③ Separation zone
Gravity does the work
The inlet diverter kills momentum. Liquid droplets fall, gas rises. Vertical height must allow droplet settling.
④ Liquid sump
Retention time check
Volume between HHL and LLL must give 1–3 min for sweet oil, 5–20 min for foamy crude. This independently sizes vessel length.
