1.1 These requirements cover shut-off valves for use on cylinders that comply with the specifications and charging and maintenance regulations of the U.S. Department of Transportation (DOT) or the corresponding specifications and regulations of Transport Canada (TC).

1.2 Valves covered by these requirements are for use on DOT or TC cylinders used in applications such as, but not limited to, automotive, medical, or industrial systems or facilities, and as covered in the following standards:

1. Liquefied Petroleum Gas Code, NFPA 58;
2. Design and Installation of Oxygen-Fuel Gas Systems for Welding, Cutting, and Allied Processes, NFPA 51;
3. Safety Requirements for the Storage and Handling of Anhydrous Ammonia CGA G-2.1, CGA/GAS K61.1;
4. Safety in Welding, Cutting, and Allied Processes, AWS Z49.1; and
5. Health Care Facilities, NFPA 99.

1.3 Gas-line shut-off valves for use with liquefied petroleum gases or anhydrous ammonia are covered by the requirements in the Standard for Valves for Anhydrous Ammonia and LP-Gas (Other Than Safety Relief), UL 125.

1.4 Gas-line shut-off valves for use with flammable gases are covered by the requirements in the Standard for Valves for Flammable Fluids, UL 842.