This publication describes the recommended industry practices and precautionary measures for filling certain liquefied and nonliquefied, nonflammable industrial, medical, and food gas cylinders not exceeding 125 lb (57 kg) water capacity. It should not be assumed that every safety precaution is included here.

This publication only covers the filling of DOT 3A, DOT 3AA, DOT 3AL, TC 3AM, TC 3AAM, TC 3ALM, authorized United Nations (UN) equivalents for these cylinders, and composite cylinders with the following gases: air, argon, carbon dioxide, helium, nitrogen, nitrous oxide, and oxygen.

This publication does not cover equipment design specifications to perform these filling operations.

This publication does not address automated or palletized cylinder filling operations or the filling of cylinders that are clustered or bundled.

This publication does not cover the filling of the following cylinders:

• Insulated refrigerated liquid cylinders such as DOT 4L and home cryogenic oxygen base units, with cryogenic liquids or refrigerated liquids. The filling of these cylinders is addressed in other CGA publications;
• Portable high pressure cylinders from other high pressure cylinders, either gas to gas (e.g., oxygen) or liquefied compressed gas to liquefied compressed gas (e.g., carbon dioxide), commonly known as transfilling; and
• Portable high pressure cylinders from home oxygen concentrators.

This publication does not cover the filling of:

• gas mixtures of any type, including reconstituted or blended air used for breathing or other purposes; and
• flammable, specialty, or liquefied petroleum gases that require additional procedures and special precautions to be taken.