This U.S. industry comprises establishments primarily engaged in the recovery of liquid hydrocarbons from oil and gas field gases. Establishments primarily engaged in sulfur recovery from natural gas are included in this industry. Cross-References. Establishments primarily engaged in-- ? Manufacturing acyclic and cyclic hydrocarbons from refined petroleum or converting refined petroleum into liquid hydrocarbons (petrochemicals) and/or recovering liquid hydrocarbons--are classified in Industry 325110, Petrochemical Manufacturing; ? Refining crude petroleum into refined petroleum and liquid hydrocarbons--are classified in Industry 324110, Petroleum Refineries; and ? Recovering helium from natural gas--are classified in Industry 325120, Industrial Gas Manufacturing.