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Commercial Diving - Dysbarisms and Other Selected Health Effects |
Printing Instructions
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Commercial Diving Laws
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Boyle's Law
applies to the expansion and contraction of gases
within the body due to external pressure changes:
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 |
| fresh water |
33.8 |
10.3 |
| sea water |
33.1 |
10.1 |
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 |
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