While the flammability of many pure gases has been well established, previously there has been no universally accepted method of categorizing the flammability of gas mixtures. This standard describes a basis for categorizing a gas mixture as flammable or nonflammable. U.S. DOT, Canadian Transportation of Dangerous Goods and International Organization for Standardization (ISO) regulations are cited as reference sources. It applies to all users, transporters and manufacturers affected by the labeling and classification requirements for gas mixtures which contain flammable components.