Area Classification-Past, Present, and Future

Properties of flammable mixtures and the fundamentals of ignition by spark discharge are described. Basic considerations of area classification are reviewed, and a brief explanation of ``class, division, and group´´ is given. Past historical facts are cited showing the development of various significant documents which detail how areas are classified. Present conditions are noted along with current review activities of these documents. New work to produce additional documents and data is mentioned. Recommendations are made for organizing an area classification committee, recording their work, and identifying the physical boundaries of classified areas. A summation and conclusions are included to detail existing problems and suggest solutions.