Pressure in oxygen cylinders shall not fall below what PSI?

• A. 60 PSI
• B. 25 PSI
• C. 40 PSI
• D. 50 PSI

Answer: (D)

Oxygen systems rely on the cylinder’s head pressure to feed the regulator and maintain the chosen flow. Once the cylinder pressure drops to about 50 psi, the regulator can no longer deliver a reliable continuous flow, so the oxygen supply may become insufficient. Therefore, the minimum safe pressure is 50 psi, below which you should replace or switch cylinders to ensure proper oxygen delivery. Values above that (like 60 psi) are still safe, while below (such as 40 or 25 psi) would not meet the required head pressure for reliable flow.