The pressure of gas in a full cylinder of oxygen is approximately ______ psi.

• A. 2000
• B. 1000
• C. 3000
• D. 500

Answer: (A)

Oxygen is stored in a cylinder under high pressure so a large amount of gas fits in the tank. For common medical oxygen cylinders, the gauge reads about 2,000 pounds per square inch (psi) when the cylinder is full. That 2,000 psi reflects the cylinder’s standard service pressure and the amount of gas available for delivery. The other numbers don’t fit the typical full-state reading: 500 psi would mean the cylinder is almost empty, 1,000 psi is mid-full, and 3,000 psi is higher than the usual pressure rating for standard medical oxygen cylinders. So, approximately 2,000 psi is the correct expectation for a full cylinder.