Vapor/Liquid (Cyclones & Demisters) Separators. A demister is a vertical vessel into which a liquid and vapor mixture (mist) is fed, and separated. Gravity causes the liquid to fall to the bottom of the vessel from which it is removed. The gas travels upward, and exits the top of the vessel. A cyclone is an adaptation of a centrifuge. The liquid is removed from the vapor by centrifugal force, and like the demister, gravity moves the liquid down and out, while the gas exits the top of the system.