This publication presents basic concepts relating to gas usage for each process and its variations. These concepts@ combined with basic information about arc welding or cutting processes@ will enable the reader to make an educated decision when selecting a gas.1 In addition@ safe practices and specific technical data are included as guides in an effort to establish optimum operation of the selected welding or cutting process.The reader will learn the process and specific advantages and disadvantages for each. Standard welding and cutting equipment is normally designed to permit the use of several gases.Note: The scope of this document does not include information for oxyfuel or heat treating processes.This specification makes use of both U.S. Customary Units and the International System of Units (SI). The measurements may not be exact equivalents; therefore each system must be used independently of the other without combining in any way. The specification with the designation C5.10 uses U.S. Customary Units. The specification C5.10M uses SI units. The latter are shown in appropriate columns in tables or within brackets [ ] when used in the text.Safety and health issues and concerns are beyond the scope of this standard and@ therefore@ are not fully addressed herein. Information on safe handling of gases and cylinders can be found in Section 6. Safety and health information is available from other sources@ including@ but not limited to@ ANSI Z49.1@ Safety in Welding@ Cutting@ and Allied Processes@ applicable federal and state regulations@ and local safety codes.1. In this document@ the use of the term gas also includes ??gas mixture.??