Which statement about high-pressure cylinders is true?

Which statement about high-pressure cylinders is true?

• A. They use 1000 psi.
• B. They use 3500 psi.
• C. They use 5000 psi.
• D. They use 4000+ psi.

Answer: (D)

High-pressure cylinders used for breathing air are designed to hold air at very high pressures, typically around 4500 psi for a full cylinder. Saying they use 4000+ psi accurately reflects this standard working range, since full SCBA cylinders commonly sit at about 4500 psi. The other numbers don’t match the typical full capacity: 1000 psi is far too low to be considered full, 3500 psi would indicate a partially used cylinder and isn’t the standard full pressure, and 5000 psi exceeds the common rating for standard SCBA cylinders. This explains why 4000+ psi is the best description of the pressure these high‑pressure cylinders are designed to hold.

High-pressure cylinders used for breathing air are designed to hold air at very high pressures, typically around 4500 psi for a full cylinder. Saying they use 4000+ psi accurately reflects this standard working range, since full SCBA cylinders commonly sit at about 4500 psi. The other numbers don’t match the typical full capacity: 1000 psi is far too low to be considered full, 3500 psi would indicate a partially used cylinder and isn’t the standard full pressure, and 5000 psi exceeds the common rating for standard SCBA cylinders. This explains why 4000+ psi is the best description of the pressure these high‑pressure cylinders are designed to hold.