# Dense Gas Dispersion #fundamental #gas-dispersion #safety Dense gases are heavier than air and form the largest group of dispersing substances in industrial environments. They flow downward due to gravity and can travel long distances before dilution. ## Characteristics - Density greater than air - Motive force: gravity - Dispersion follows terrain gradient - Falls like a waterfall, flows like water - Travels long distances before natural dilution - Not easily distorted by wind - Can enter basements, tunnels, wells ## Examples - Heavier-than-air gases - Vapors from evaporating liquids - Cold gas clouds (initially dense, then become buoyant as they heat) ## Detection Strategy - Mount detectors close to the ground - Position in presumed pathway of gas cloud - Consider structures, walls, and dikes that alter flow - Account for cold gas behavior (dense initially, then buoyant) ## Safety Implications Dense gas clouds are extremely dangerous because: - They can disappear into confined spaces - Countermeasures are difficult once gas enters structures - Migration paths are predictable, making detector placement straightforward - Long dispersion distances create larger danger areas ## Visual Indicators Cold dense gas clouds may condense water vapor, producing visible fog. ## Related Concepts - [[Neutrally Buoyant Gas]] - [[Aerosol Formation]] - [[Gas Detector Placement]]