What it does
Estimates usable minutes of continuous-flow oxygen above the selected cylinder reserve. The interactive tool defaults to a 200 psi reserve.
The formula
usable minutes = max(0, gauge psi − reserve psi) × cylinder factor ÷ flow L/min. Factors in L/psi: D 0.16, E 0.28, M 1.56, G 2.41, H/K 3.14. The tool rounds down to whole usable minutes.
Worked example
For an E cylinder at 2000 psi, a 200 psi reserve and continuous flow of 2 L/min: (2000 − 200) × 0.28 ÷ 2 = 252 usable minutes, or 4 hours 12 minutes.
Good to know
This is a study estimate for continuous flow, not pulse-dose delivery. The actual cylinder factor, reserve and device must be confirmed; at or below the selected reserve, the tool shows zero usable minutes.
Open the interactive calculator