Dalton’s Law in Scuba
By: Iheukwumere Marcus
What is Dalton’s Law?
 Law of Partial Pressure
 (PTotal = P1 + P2 + P3 . . .)
 The whole is the sum of it’s parts
Calculations using Dalton’s Law
 Each 10 m of depth the
pressure increases by 1
atm.
 Absolute pressure thus
increases
 Partial pressures increases,
but percentages stay the
same.
Gas
Air
Pressure on
Pressure at
surface (atm) 50msw (atm)
1
6
Nitrogen,
79%
0.79
4.74
Oxygen,
21%
0.21
1.26
Air made
up of:
Implications for Scuba Diving
Lungs fill to
the same
volume
Therefore
more gas
molecules
inhaled
More
pressurized
gas in the
bloodstream
Nitrogen
Narcosis
Oxygen
toxicity
Precautions taken based on Dalton’s Law
Longer Decompression
 Too fast can lead to air bubbles
 They can form and move anywhere
 DCS
Heliox
 Helium and Oxygen mixture
Sources
 https://oceanexplorer.noaa.gov/edu/lessonplans/breath.pdf
 http://www.thediverclinic.com/mobile/diving-gas-laws.html/
 http://www.scubadiverinfo.com/2_physics.html
 https://www.ncbi.nlm.nih.gov/books/NBK470304/
 https://en.wikipedia.org/wiki/Dalton%27s_law