Medical Oxygen Cylinder Duration Calculator

Once a cylinder drops below roughly 10% of full pressure, the gauge becomes unreliable and the last bit of gas may not flow at the set rate. Clinical practice is to swap or refill before the gauge hits the reserve threshold. The 200 psi / 14 bar reserve is widely taught — see Cornell PICU and Virginia Department of Health guidance.

Nasal cannula: 1-6 L/min (effective max ~6). Simple face mask: 5-10 L/min. Non-rebreather mask: 10-15 L/min. High-flow nasal cannula (HFNC): 2-60 L/min, titratable to the patient. Always use the value displayed on your flow meter, not what was prescribed in theory.

Both measure pressure. UAE, UK, and Europe use bar; the US uses psi. 1 bar ≈ 14.5 psi. So a full 200 bar UAE cylinder is roughly 2,900 psi, and a full 2,000 psi US E-cylinder is about 138 bar. Always check which unit is printed on your cylinder gauge before reading.

UAE follows European/UK medical-gas standards. Most common: 10 L water capacity (portable) and 40 L (fixed or transport) at 200 bar. UK BOC sizes are also seen in private hospitals — CD (460 L @ 230 bar), HX (2,300 L @ 230 bar), ZX (3,040 L @ 300 bar). Confirm with your supplier (Air Liquide, Linde Healthcare, Sharjah Oxygen).

The formula assumes ideal-gas behaviour and a linear pressure-to-volume relationship. Below about 200 psi (14 bar), gauge accuracy degrades and the residual gas approaches ambient pressure, so the last 10% of indicated pressure delivers less usable gas than the formula predicts. The safety reserve protects against this.

No. It is an estimate to support — never replace — clinical assessment, your facility's protocols, and direct reading of the cylinder gauge. Patient acuity, cylinder age, gauge calibration, and altitude can all affect actual duration. Always have a backup cylinder ready in any clinical setting.

On a portable cylinder the pressure gauge sits at the top of the regulator yoke — usually a small dial graduated 0-200 bar (or 0-3,000 psi). Read it with the cylinder vertical and the regulator at zero flow for the most accurate reading.