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Transcript of SCUBA
Scuba is an activity in which a person can breathe and swim underwater for large amounts of time using a tank filled with breathing gas for air. They do this explore the underwater world for recreational or research/professional purposes. Buoyancy: Buoyancy is a diver’s ability to float and their ability to sink, rise, or do neither. A diver wants to control their buoyancy on their ability to ascend or descend. A descent in the water reduces the buoyancy and an ascent will increase the buoyancy. Pressure: Pressure is the amount of force per unit area. History
Underwater exploration has been around since the 1700’s, though it was not available to the everyday people. Air would be delivered to the diver using a hand-operated pump to push air through a hose. This device did not allow the diver to stay underwater for extended amounts of time. History
In 1943, Jacques Cousteau and Emile Gagnan developed the first self-contained underwater breathing apparatus that delivers pressurized air into the diver only when they breathed in. This is called the Aqua Lung. Equipment
Circuit Rebreather: A rebreather is the whole apparatus that allows the diver to breathe underwater. It takes the carbon dioxide that is exhaled out of the person’s mouth and recycles it to regulate the oxygen back into the person. This rebreather has many components to it including the tank, pressure gauge, and mouthpiece. Equipment
Wet/Dry Suits: These suits cover the whole diver for thermal insulation. Wet suits are used in warmer waters, letting water get into the diver for their skins to warm the water up. A dry suit keeps the diver completely dry, due to frigid waters. Equipment
Diving masks: Diving masks help the diver to see clearly underwater. It creates a waterproof seal around the face to keep out water and protect against any water pressure. Equipment
Swim fins: Swim fins help the mobility of the diver underwater. Equipment
Buoyancy compensator (BCD): This is a bladder worn by the divers that adjust and control the overall buoyancy of a diver. Buoyancy is controlled through changing the volume of air in the bladder. Statistics: Fatalities
1 out of every 211,864 dives end in a fatality.
The three main causes of fatalities are:
1. Pre-existing disease in the diver
2. Poor buoyancy control
3. Rapid ascent/ violent water movement Scuba Tanks: The air in the oxygen tanks is compressed about 200 times to the pressure of the air in the atmosphere.
Compressed air contains oxygen and nitrogen.
Nitrox is mixture of air with oxygen. This mixture prevents from decompression sickness from the diver being exposed to high pressures of water.
Other less common mixtures are trimix and heliox. Trimix is oxygen, helium, and nitrogen. Heliox is helium and oxygen. Gas Laws Seawater is a lot denser than air so a diver is exposed to greater pressures as they go deeper. The diver needs to breathe pressurized air because the lungs cannot expand enough to stand high pressures. There are laws that explain the physics of scuba diving: Boyle’s Law: This law describes the relationship between volume and pressure of a gas held at a constant temperature.
Formula: PV=k or P1V1=P2V2
P= pressure of gas
V= volume of gas
k= a constant
As pressure increases, volume decreases. As pressure decreases, volume increases. Boyle's Law
In the world of scuba diving, volume decreases as you dive deeper into the sea with greater pressure. Your buoyancy compensator will look smaller because the volume is being compressed into a smaller space. While descending, you need to inhale more due to the decrease in volume of your lungs and tubes.
While ascending volume increases while pressure decreases. You need to exhale more as you ascend because the volume of your lungs will increase. The BCD will look bigger, so the air needs to be released out of it. This needs to happen, or the diver will lose control of depth and be thrown off in buoyancy. Charles’ Law: This law describes the relationship between the temperature and volume of a gas held at constant pressure.
Formula: T/V=k or V1/T1=V2/T2
T= temperature of gas
V= volume of gas
k= a constant
At a constant pressure, volume increases as temperature increases. Volume decreases and temperature decreases. Charles' Law
If the temperature of the gas in a SCUBA tank increases, the volume will increase inside of the tank. If the temperature of the gas decreases, then the volume will likewise decrease. This shows that you should not leave your SCUBA tanks out in the sun, in back trunk, or in hot places for extended periods of time. Your tank will most likely be damaged or even burst due to high pressures in high temperatures. Dalton’s Law: This law describes the relationship between the pressure of mixed gases and pressure of individual gases.
Formula: P= p(1) + p(2) + p(3) ... + p(n)
P= total pressure
p= sum of pressures
n= number of individual gas pressures
The pressure of the mixed gases is equal to the sum of the pressures of individual gases. Dalton's Law:
Mixed gases will stay in the same proportions under any pressure.
In the world of scuba diving, the scuba diver’s body must be at the same level of pressure everywhere throughout it’s body no matter the depth, so they will be able to plan dives and know gas levels in their body. Henry’s Law: This law describes the relationship between the the behavior of gases and the volumes of liquid.
P= partial pressure of the gas
C= concentration of the gas
At a constant temperature, the amount of gas dissolved in a liquid will be directly proportional to that of the partial pressure of the gas. Henry's Law:
The partial pressure of the gas is equal to the constant of the concentration.
You will absorb more gases as you are exposed to higher amounts of pressure in the ocean. You are at greater risk for absorbing excess amounts of chemicals, leading to decompression illness. If you, as a diver, can see the possible risks of diving deep, then you can also prevent it while enjoying it at the same time. Barotrauma: This is a pressure related injury that can happen in the ear, lung, etc. This relates to Boyle’s law because An ear barotrauma happens when a diver’s ears are unable to equalize with the water around it and mostly occur in shallow water(the air trapped in his ears expands as he ascends). The symptoms are increased pressure and pain in the ears. This can be avoided by never diving when congested, equalize properly, and don’t use earplugs. This can be treated by a prescribed decongestant and antibiotics or may heal on own if minor. There is also pulmonary barotrauma, which occurs in the lungs and this happens when the diver doesn’t exhale air while returning to the surface, so their lungs are filled with too much air, therefore an overload of pressure(relates to Boyle’s law because the lungs expand as the diver ascends). The symptoms are coughing up blood and chest pain. This can be prevented by never holding your breath and ascending slowly and can be treated by inserting a tube into the chest to release the air in the lungs. Risks Barotrauma: There is also pulmonary barotrauma, which occurs in the lungs and this happens when the diver doesn’t exhale air while returning to the surface, so their lungs are filled with too much air, therefore an overload of pressure. The symptoms are coughing up blood and chest pain. This can be prevented by never holding your breath and ascending slowly and can be treated by inserting a tube into the chest to release the air in the lungs. the “bends”(Henry’s law)-DCS(Decompression sickness or the bends) This sickness relates to Henry’s law because when a diver is very deep their body’s tissues have absorbed a lot of nitrogen, so when the diver begins to return to the surface too fast the pressure reduces rapidly making the nitrogen escape as bubbles. In order to avoid the bends the diver must return to surface slowly and keep an eye on the time and his depth, so he can make sure he isn’t absorbing too many chemicals. The symptoms are joint pains in the legs and arms,itching, and lymph nodes,breathing and ear problems The treatment includes giving diver oxygen and IV fluids and recompression. Works Cited
"1900s - 2000s Underwater Exploration Timeline-University of Wisconsin Sea Grant." UW Sea Grant. N.p., n.d. Web. 2 Mar. 2013. <http://www.seagrant.wisc.edu/madisonjason11/timeline/index_1900.html>.
"An Introduction to Scuba Gas Laws - Part 2: CharlesÃ¢Â€Â™ Law." SCUBA Diving News Blog from Aquaviews. N.p., n.d. Web. 3 Mar. 2013. <http://aquaviews.net/scuba-guides/an-introduction-to-scuba-gas-laws-part-ii-charles-law/#>.
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Category. "History of Scuba Diving - Jacques Cousteau." Inventors. N.p., n.d. Web. 5 Mar. 2013. <http://inventors.about.com/od/cstartinventors/a/Scuba.htm>.
Category. "Is Scuba Diving Safe - Statistics, Risks, Facts, and Dangers." Scuba Diving - Lessons, Certification, Theory, Gear, and Travel . N.p., n.d. Web. 3 Mar. 2013. <http://scuba.about.com/od/divemedicinesafety/p/Is-Scuba-Diving-Safe-Or-Dangerous.htm>.
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Thomas, Edwin. "What Gases Are in a SCUBA Tank? | eHow.com." eHow | How to Videos, Articles & More - Discover the expert in you. | eHow.com. N.p., n.d. Web. 28 Feb. 2013. <http://www.ehow.com/facts_4922373_what-gases-scuba-tank.html>.
"What Are the Dangers of Scuba Diving? | USA Today." Travel Tips - USA Today. N.p., n.d. Web. 4 Mar. 2013. <http://traveltips.usatoday.com/dangers-scuba-diving-2492.html>. Dalton's Law A & C D C I V I N G O M P A Y N Oxygen Toxicity(Dalton’s Law): There are two types, CNS, which is caused by diver’s diving to a point that their oxygen partial pressure exceeds 1.6 ata and can result in uncontrollable muscle contractions or death. This relates to Dalton’s law because the partial pressures of oxygen combine, which may produce an excess amount of oxygen. The other type is pulmonary oxygen toxicity, when a diver is enduring large partial pressure for a long time and this can give the diver coughing, shortness of breath, and lung failure. No matter what the type, the oxygen becomes toxic, so in order to avoid this a diver shouldn’t dive too deep, take breaks, and monitor oxygen intake. The oxygen becomes toxic because oxygen is used to perform basic cell functions, during this process the oxygen cells collide creating free radicals that are normally destroyed, but as the diver gets deeper more oxygen cells are created, making the oxygen toxic. This can be treated by giving the diver 100% oxygen. Gas Embolisms: This is is a blockage in the arteries created by air.This is caused due to Boyle’s law this condition is caused by the expansion of dissolved gases in the blood. These gases expand as pressure decreases.The severity of a gas embolism depends on which blood supply is is unable to reach a particular tissue. The symptoms are blurred vision,dizziness and diver will go into cardiac distress. This can be avoided by never holding your breath and not diving when you are ill with mucus in your throat and ascending slowly. This can be treated by recompression and breathing pure oxygen under high pressure. Nitrogen Narcosis: This relates to Dalton’s law, since when a diver’s nitrogen is contaminated because it has exceeded a partial pressure at great depths. The deeper a diver descends, the higher the partial pressure of nitrogen and other gasses in his air will be. This relates to Dalton’s law because the combined pressure of the gases determines the contamination of the nitrogen. This can be detected by an odd taste or smell in the scuba tank, to avoid change the tank or drain if a smell or taste is detected. The symptoms are lightheadedness,hallucinations,poor judgment or a coma. The treatment is ascending from the depth. Boyle's Law Henry's Law