What is the recommended storage level for a high-pressure scuba cylinder?

Storing a high-pressure scuba cylinder with a minimum of 500 to 750 psi is important for several reasons. This pressure level ensures that the cylinder is sufficiently filled to prevent moisture from entering the tank. A higher internal pressure maintains a seal at the valve, which helps to minimize the risk of contamination and corrosion developing inside the tank.

Furthermore, having a substantial amount of air in the tank is crucial for maintaining the integrity of the cylinder over time. It is also a good practice to keep the cylinder under pressure during storage, as it helps to avoid possible deformation of the tank and seals. This level of pressure provides a safety margin, allowing for the potential loss of some pressure over time without dropping below a functional storage level.

In contrast, storing a cylinder flat without air or with very low pressure can lead to rust and other forms of corrosion because moisture can accumulate inside the tank. Similarly, keeping the valve open is not advisable as it exposes the cylinder to contaminants in the air, which can introduce water vapor and dirt into the cylinder.