An overview of the physics of scuba diving.

1. The Physics of Scuba Diving
By Melissa Glaser

2. This presentation will address:
 Brief history of Scuba
 How a regulator works
 Air laws in effect

3. History of Scuba
 1878- Henry Fleuss invents a self contained underwater breathing unit.
 1925- Yves Le Prieur releases a more advanced breathing unit.
 1943 - Jacques-Yves Cousteau and Emile Gagnan design and test the
first Aqua-Lung.
 1956 - First wetsuit was introduced by University of California. Ted
Nixon introduces the red and white “Divers Down” flag.

4. • Regular breathing makes use of
differences in air pressure
• The water above a diver increases the
atmospheric pressure. Therefore,
• Air must be pressurized to be able to
breathe at a pressure of more than one
Atmosphere (air pressure at sea level).
(This is also why you have to pop your ears as you descend.)
Underwater breathing

5. First Stage
The part of the regulator that attaches to
the tank and reduces the pressure of
the air in the tank to an intermediate
pressure.
First stage - diagram

6. Second Stage
The part of the regulator at the end of
the hose that includes the mouthpiece.
The second stage reduces the pressure
in the hose to a breathable pressure.
Second stage - diagram

7. Gas Laws
Boyle’s Law
“For any gas at a constant temperature, the volume of the gas will vary inversely
with the pressure, and the density of the gas will very directly with the pressure.”
If T= constant, then V  1/P and Density P
(Never hold your breath!)

8. Charles’s Law
For any gas at a constant pressure, the volume of the gas will very
directly with the absolute temperature.
If P= constant, then V  T
Or
For any gas at a constant volume, the pressure of the gas will vary
with the absolute temperature.
If V= constant, then P  T
(keep tanks cool and don’t fill them too fast.)

9. Dalton’s Law
The total pressure exerted by a mixture of
gases is equal to the sum of the
pressures of each of the gases making
up the mixture, with each gas acting if it
alone was present and occupied the
whole volume.
(Sum of parts equals the whole!)

10. Henry’s Law
The amount of any given gas will dissolve
in a liquid at a given temperature is
proportional to the partial pressure of
that gas in equilibrium with the liquid
and the solubility coefficient of the gas
in the particular liquid.
An increase in pressure will increase absorption
(Oxygen in your blood dissolves at a given pressure.)

11. Bert’s Law
Pressure can be reduced by 1/2 or less without
a gas coming out of a solution.
This is like carbonation in a coke can.

12. Martini’s Law
Nitrogen absorbed under pressure has a
narcotic effect.
(A diver can get “narked” at any depth, for no
reliable reason, and it differs every dive. Past
100’ everyone is narked.)

13. Archimedes Principle of Buoyancy
An object is buoyed up by a force equal to the
weight of the liquid it displaces

14. Bibliography
http://www.divinghistory.com/timeline.htm
http://www.newdiver.com/gear/divespeak.shtml
http://entertainment.howstuffworks.com/scuba1.htm
www.cousteausociety.org/ tcs_people.html
www.divingheritage.com/ dragerkern.htm