A high pressure scuba cylinder should be stored:

Storing a high-pressure scuba cylinder securely is essential for safety and maintenance. When a cylinder is stored, it should be upright and secured to prevent it from tipping over or falling, which could cause valve damage or result in an uncontrolled release of gas. Additionally, maintaining a residual pressure of 500 to 750 psi in the cylinder helps prevent contaminants from entering through the valve, ensuring that the cylinder remains in a safe and serviceable condition. Having this residual pressure can also help keep moisture out, reducing the risk of corrosion inside the cylinder. Therefore, securing the cylinder and maintaining a minimum pressure is critical for both safety and equipment longevity.