What Is a Gas Coalescing Separator: Mechanism, Design and Applications Answering the core question: What is a gas coalescing separator? A gas coalescing separator is a two-stage vessel that removes very fine liquid aerosol from gas by first merging the tiny droplets into larger ones and then separating the enlarged droplets by gravity or by a vane pack. In the first stage, gas passes through a bed of fine fibrous coalescing elements where droplets from 0.1 to 1 micrometre are