Air-to-Oxygen Ratio: Magic Box
Follow the table guide to determine the air-to-oxygen ratio the Magic Box. Using the Magic Box ratio will help estimate the total flow using total flow = flowmeter setting × factor.
Accuracy: —
Streak: 0
Magic Box
FiO₂ and flowmeter changes automatically recalculate and auto-animate. Total-flow calculation now appears in its own box.
Changing FiO₂ now automatically computes and animates the chart.
Magic Box
Air value
30
Oxygen value
50
Air : Oxygen ratio
30 / 50 = 0.6:1
Factor (Air + O₂)
1.6
Changing this updates the total-flow calculation automatically.
Total flow calculation
Air = 30, Oxygen = 50, Factor = 1.6.
Total flow = 5 × 1.6 = 8 L/min.
Total flow = 5 × 1.6 = 8 L/min.
Estimated total output flow
8 L/min
Ready.
Enter a desired FiO₂ and the chart will update automatically.
How the factor is used
The table logic is Total Flow = Flowmeter setting × Factor.
The Factor is the air-to-oxygen ratio plus 1.
Example: at 70%, the ratio is 0.6:1, so the factor is 1.6.
Why more air entrainment lowers FiO₂
Air-entrainment systems pull room air into the oxygen stream. More entrained air increases total flow, but it also dilutes the oxygen, so delivered FiO₂ decreases.
Fixed-orifice meaning
In a fixed-orifice entrainment device, changing the input flow changes the total output flow much more than it changes the delivered FiO₂. FiO₂ usually stays close to the manufacturer setting.