← Dive Tools
Dive Tools logo

CCR Setpoint vs Gas-Use Calculator

Compare onboard O2 consumption and CNS exposure across multiple ppO2 setpoints for a given dive profile. Models metabolic O2 use plus loop top-off during descent.

Part of the Dive Tools toolkit by Chris Uriarte

Inputs

Units:

Dive profile

ft
ft
Used for the descent loop top-off term.
min
L/min
~1.0 L/min at rest; 1.5–2 L/min working.
L
Counterlung capacity (typically 4–8 L).

Onboard O2 cylinder

cu ft

Setpoints to compare

ata
ata
ata

Comparison

Setpoint Metabolic O2 Loop top-off Total O2 used Cyl pressure used Cyl pressure remaining CNS% CNS status
About the model: O2 use ≈ metabolic consumption (driven by time × work rate, independent of setpoint) plus a one-time loop top-off during descent (loop volume × max-ATA × setpoint). Setpoint mostly affects CNS exposure, not cylinder duration. CNS% is computed against NOAA single-exposure limits at the setpoint ppO2.

THESE TOOLS ARE FOR REFERENCE PURPOSES ONLY. USE AT YOUR OWN RISK.