When a vapor steam carrying entrained liquid droplets passes through a demister pad, the vapor moves freely through the knitted mesh but the inertia of the droplets causes them to contact the wire surfaces and coalesce, the large droplets drain by gravity, and drop to the bottom of vessel.
When installing the demister, the demister pad must fit tightly to the wall of the column or vessel or tower to prevent any gas leaking from the contact surface. When properly designed demister pads can give efficiency up to 99.9% with minimal pressure drop.
