What is the primary purpose of a collar on a compressed gas cylinder?

The primary purpose of a collar on a compressed gas cylinder is to protect the valve. The collar is designed to provide a protective framework around the cylinder's valve, which is the most vulnerable part of the cylinder since it is exposed and can be damaged easily. A damaged valve could lead to leaks or safety hazards. By securing the valve with a collar, the integrity of the cylinder is maintained, enhancing safety during transportation, storage, and handling.

While indicating the gas type, securing the cylinder, and enhancing visibility might be important aspects in certain contexts, they are not the primary function of the collar itself. The collar's main role centers on safeguarding the valve to prevent operational hazards.