The report gives results of a 3-year program to assess the environmental impact of petroleum refining atmospheric emissions. This volume gives a detailed characterization of petroleum refinery technology, prepared as part of the program. Peteroleum refineries in the U.S. are listed, characterized, and classified according to their types and complexities. It describes four types or sets of refinery models which could be used to simulate the entire refinery industry. It gives the characteristics of crude oils, other raw materials, and intermediate and final products. A major portion of this volume is a detailed description of current refinery process technology and auxiliary operations. It describes the purpose, operation, energy needs, and utility requirements. It includes simple flow diagrams for most processes. It gives a detailed estimate of the number of fugitive emission sources for each process type. It also includes detailed estimates of process and fugitive non-methane hydrocarbon emissions for major refinery process units.