SCBA Air Duration

Theoretical air-cylinder duration from cylinder volume, pressure, and consumption rate. Apply safety factor.

LSASCBA

Cylinder volume (water)LCylinder pressurebarBreathing rate (hard work)L/minRest 20; light 25; moderate 35; heavy 40; very heavy 55+.Reserve fraction%

Total free air: 2,040L

Usable duration: 38.3min

Changing the inputs requires JavaScript. The calculator above shows its default inputs and result. The formula, symbols, and regulatory sources are shown in the Formula section below.

Formula, assumptions, and limits

t = \frac{V_\text{cyl} \cdot P}{\text{RMV}} \cdot (1 - \text{reserve})

Symbol	Meaning	Unit
$V_\text{cyl}$	Cylinder water-volume	L
$P$	Service pressure	bar
$RMV$	Respiratory minute volume	L/min

Source: SOLAS II-2 Reg 10 / FSS Ch.3; EN 137 - Respiratory protective devices

In short

Theoretical air-cylinder duration from cylinder volume, pressure, and consumption rate.

Learn the theory LSA Code: International Life-Saving Appliance Code