Commercial Diving Laws
Boyle's Law applies to the expansion and contraction of gases within the body due to external pressure changes:
PV = constant
If the pressure starts out as one atmosphere at the surface, it increases linearly with depth under water depending upon the density of the water:
PATA = 1 + (depth/kappa)
where kappa depends on the density of the water and units of depth:
|Value of kappa|
|Depth in feet||Depth in meters|
Dalton's Law states that in a mixture of n gases the partial pressure of each gas [Pi] is proportional to the molar fraction of each gas [Yi] that makes up the total:
PTotal = P1 + P2 + ... + Pn = Y1PTotal + Y2PTotal + ... + YnPTotal
Dalton's Law can be used to determine how much nitrogen, oxygen, or carbon dioxide is in the ambient air at any hyperbaric pressure underwater.
Henry's Law states a gas will dissolve into a liquid in proportion to its partial pressure in the air and its solubility in the liquid.
Ci in solution = Si × Pi
where Si = solubility coefficient of gas i in a given solute, cc/mL/atm.
Henry's Law can predict the body's absorption of inert gases into and back from the body at any pressure or depth.
|Increasing severity of nitrogen narcosis symptoms with depth in feet and pressures in atmospheres.(1,3,6)|
|Depth||P Total||P N2||Symptoms|
|100||4.0||3.0||Reasoning measurably slowed.|
|150||5.5||4.3||Joviality; reflexes slowed; idea fixation.|
|200||7.1||5.5||Euphoria; impaired concentration; drowsiness.|
|250||8.3||6.4||Mental confusion; inaccurate observations.|
|300||10.||7.9||Stupefaction; loss of perceptual faculties.|
|Symptoms and terminology of DCS.|
|Location of Bubbles||Symptom(s)||DCS Type||Common Term|
|Joints||Pain upon flexure.||I||Bends|
|Skin||Altered skin sensation, itching, or rash.||I|
|Brain-spine||Dizziness, headache, loss of coordination, weakness.||II||Staggers|
|Chest||Cough, dyspnea, pain upon breathing.||II||Chokes|