Heading 2705 covers gases manufactured from solid carbonaceous feedstocks (coal, coke, peat) through gasification or similar processes, such as producer gas and water gas. Heading 2711 covers petroleum gases and other gaseous hydrocarbons — including LNG, propane, and butane — derived from petroleum or natural gas sources. The feedstock and production route determine which heading applies.

Because coal gas and producer gas are difficult to liquefy and store, cross-border trade usually occurs via pipeline or as part of integrated industrial facilities rather than in bulk cargo shipments. Importers dealing with pipeline gas should confirm that the gas composition and origin documentation support the 2705 classification rather than 2711.