What is the primary purpose of a steel safety cap on a compressed gas cylinder?

The primary purpose of a steel safety cap on a compressed gas cylinder is to protect the valve stem. The valve stem is a critical component of the gas cylinder, and it controls the release of gas. If the valve stem is damaged, it can lead to a hazardous situation, such as a gas leak or uncontrolled release of pressure. The safety cap acts as a protective barrier that prevents physical impact, debris, or accidental knocks that could compromise the integrity of the valve. By covering the valve stem, the cap significantly enhances the safety of handling and storing the gas cylinder, thereby reducing the risk of accidents.

The other options do not accurately represent the main function of the steel safety cap. Increased cylinder pressure is achieved through the design and manufacturing of the cylinder itself, while extra storage capabilities relate to the cylinder's overall design, not the cap. Although handling might be improved with a cap, its primary function remains focused on the protection of the valve stem.