What happens to water pressure as a diver descend?

Answer 1

Water presure doubles every 33 feet. Water presure doesn't actually double every 33 feet. It actually increases in pressure by one atmosphere every 33ft. Thus at 33ft the pressure would be twice what it is at the surface. At 66ft however the the pressure would be three times that at the surface... 99ft, 4 times and so on.

Answer 2

Pressure while diving has a compression effect on your body, with air cavities such as lungs, sinus, and ear canal being the most affected. Every ten feet of water depth increases the pressure by 14.3 pounds per square inch. Since that is also the average pressure at the surface, the first ten feet you are then doubling the pressure surrounding you. As an example, if you take a balloon filled with air at the surface, then drag it down to a depth of ten feet, its volume would become half of what it was at the surface. Not that you would have half the air content, but rather half the physical volume due to the compression.

This is the reason why when you are diving, you will need to compensate for the pressure against your ear drums to relief the pain. The pressure on the outside being greater then your internal pressure, it will push and stretch your ear drums until they burst if not compensated. You will get a similar but reverse effect with altitude while flying in an airplane as the pressure now decreases the higher up you go.

This said, depth will dictate how long you will be able to stay under water and at what depth for the size of Scuba tank you have. Because of the air volume will be reduced with depth, your lung will need to take more air in to satisfy your breathing needs, thus the deeper you go the less time you will be able to stay under.

Pressure has a more critical and dangerous effect on your body if you scuba dive (with air tank), then if you were just free diving. In free diving, you are going down and come back up with the exact same air volume in your lungs then when you started. While scuba diving on the other hand, the deeper you go the more air you will have in your lungs, thus the more air will have to be exhale as you go up. Lets say that one breath at the surface fills your lungs with one gallon of air. At ten feet the same breath will take 2 gallons (compressed down into 1 gallon). If you were to hold your breath and come back up at the surface, the 2 gallons would now expand to be 4 gallons, thus bursting your lungs open to put it simply.

Pressure has also more complex effect on your body such as the amount of gasses (oxygen-nitrogen) that will be dissolved into your blood stream while scuba diving. Very critical phenomena to understand in order to accomplish safe diving. (See scuba diving decompression table).

Answer 3

As your body is made up of mostly water (which doesn't compress well under pressure) the only bit that are affected are the air spaces. Your lungs expand and contract fine as the 2nd stage reg keeps the air at the same as ambient pressure - so it doesn't feel any harder to breathe. Your ears have to be equalised as you descend, which is the same as you do in a plane when your ears pop except you do it more frequently. Other than that you don't notice much of a difference at 2ft as you do at 100ft. The main thing you can tell the difference is your wetsuit compressing.

Answer 4

ok.. Everyone has nitrogen content in the joints of there bones. If you have ever cracked your knuckles that's the nitrogen content being released. When divers go into the water the nitrogen compresses. When they come up it expands. This is what people call the bends. They become adjusted to pressure by comming up very slowly. Else the bends could affect your spinal chord and make you paralyzed. When ever you dive you must NOT go on a plane for 24 hours to let your nitrogen pressure go back to normal.

Answer 5

The average human uses about 25 litres of air per minute (at sea level) and since a scuba tank is between 10 and 15 litres, if the gas wasn't compressed, it wouldn't even last a minute.

By compressing the gas, it is possible to get 4500 litres of air or more in to the tank. This means the diver has much more air to use on a dive

Air consumption per minute is tidal volume x breaths/minute. Average for an adult is 0.5 liters x 20 bpm = 6 lpm. Also the most common scuba tank holds 80 cubic feet or ~ 2300 liters.

Answer 6

Every 33 feet (or 10 meters) that a diver descends, it increases the pressure on his body by 1 atmosphere. So a diver at the surface will be under 1 atmosphere of pressure (from the air), a diver at 33 feet will be under 2 atmospheres (air + 33 feet of water), and so forth. Divers cannot normally feel this pressure, because their diving equipment provides compressed air to breathe at the same pressure as their current depth, however, the pressure does have a number of effects:

• The deeper a diver goes, the faster they will consume their air supply. A diver who consumes 1 cubic feet of gas per minute at the surface, will consume 4 cubic feet of gas per minute at a depth of 99 feet.

• The diver's body will absorb nitrogen from breathing compressed air at a faster rate the deeper that he goes. If divers absorbs too much nitrogen, they will need to decompress before returning to the surface, or they will suffer decompression sickness (the "bends") when they ascend. The penalty for diving deeper is exponential. A normal diver can spend about 60 minutes at 60 feet without needing to decompress. A 90 feet that is reduced to about 30 minutes. At 120 feet, only about 10 minutes. Some divers breathe oxygen enriched air (called "Nitrox") to enable them to stay deeper longer without needing to decompress.

• For reasons that are not fully understand, when a diver goes deep, the nitrogen effects the nervous system and causes narocis, sometimes called "rapture of the deep". The experience is very much like being drunk; it slows reactions times and muddles thinking, leading some divers to put themselves in danger. Symptoms of narcosis vary, but become noticeable in most divers at depths of about 100 feet and deeper. Divers engaging in very deep diving usually use helium mixes, as helium is much less narcotic than nitrogen.

• When a diver goes extremely deep they may also be at risk of oxygen toxicity. If a diver breathes oxygen at too high a pressure this can cause the diver to black out. Ordinary air is only 21% oxygen, but at depths of 180 feet or greater, even air can become toxic if beathed for too long a period of time. Oxygen toxicity is a particular risk for divers who are using Nitrox (see above).

Most diver training agencies offer "deep diving" courses for divers who wish to go to depths greater than normal. For diving beyond 130 feet, divers should seek specialised training in "technical diving".

Answer 7

There are a number of effects that pressure has on a diver's body, and a number of ways that a diver mitigates these effects in order to return safely to the surface. Divers encounter both the mechanical effect of pressure and the effect of compressed gases under pressure and must use certain techniques to avoid injury by these effects.These techniques are taught in any "Open Water Diver" introductory course, and are built upon as a diver gains more and more training.

The direct mechanical effect of hydrostatic pressure on the human body while diving is one such effect. Since most of the human body is made from water and exists in a liquid state, this pressure is distributed evenly across the body and has little, if any, affect on most of your body. (Water won't crush water!)

Any air spaces in your body and equipment, however, are affected by this mechanical pressure. You may have felt pressure on your ears while swimming to the bottom of a swimming pool. Your middle ear is filled with air, as are your lungs, your airway, your sinuses, and a few added pieces of equipment used while diving such as your mask.

Outside pressure compresses the air inside an air space, causing the air space to change its volume to compensate. To prevent any ill effects from this phenomenon, a diver adds air to these air spaces while descending. This is called "equalizing." You can equalize your ears and sinuses by blocking your nose with your fingers while gently trying to blow through your nose until you feel a "pop" in your ears. This is called the "Valsalva maneuver."

As the diver ascends and the pressure is slowly relieved from their body, the air in the body's air spaces expands and must be allowed to escape to prevent damage to tissue. This is why the "Golden Rule" of scuba diving is "Never hold your breath," as holding your breath while ascending would cause air in your lungs to expand and potentially injure your lungs.

These mechanical effects of pressure are easily mitigated with the techniques taught in any introductory scuba course.

The other potentially damaging pressure-related effect of diving is the effect of breathing compressed gases. Divers can breathe a wide array of mixed gases, but most diving is done with air. Air contains some oxygen, which is necessary for life, but air should not be confused with oxygen. Air is mostly nitrogen, which does very little for your body besides taking up space. Many recreational divers use a mixed gas called nitrox. Nitrox, like air, is primarily made up of oxygen and nitrogen, but at different ratios optimized for the depth of a dive. Nitrox is made by adding oxygen to air. A third gas, helium, is commonly added to air or nitrox to create a "trimix" for deeper diving.

Each of these three gases has negative effects on your body under certain circumstances. Oxygen can become toxic and cause seizures under enough pressure. Nitrogen and helium both dissolve in body tissues and can cause a condition called decompression sickness (or "the Bends") upon surfacing if a dive is not planned properly. Decompression sickness is caused by these dissolved gases coming out of solution and forming bubbles in your body, much like the dissolved gas in a soft drink fizzing when opened. Nitrogen and oxygen work together to create an effect called narcosis, which is very similar to the narcotic effect of breathing nitrous oxide (laughing gas). Helium can cause a condition called high-pressure nervous syndrome at extreme depths, where a diver loses muscular control and develops tremors.

Recreational diving is done with air or a certain range of nitrox mixtures, and dives are conducted a shallow enough depths where the effects of gas toxicity and narcosis are limited (recreational diving is limited to 130 ft). The dive times are then planned with a device such as a diving computer or table in order to avoid decompression sickness. As a result, recreational divers rarely encounter any of these negative effects.

Deeper technical and commercial diving takes a different approach. The effects of these three gases are balanced in such a way that they mitigate each other and minimize the chances of negative effects. The dive is then planned, with a slow enough ascent to avoid decompression sickness. As a result, a much wider array of depths and dive times are possible.

Oxygen is used for some very specific types of diving, but it is relatively rare to see a diver breathing oxygen as this gas would become toxic at any depth greater than about 20 feet. You mentioned Navy SEALs in your post as a category... SEALs do much of their diving with a simple, yet sophisticated, closed-circuit rebreather that supplies pure oxygen to the diver. This allows them to stay submerged for extended periods (about four hours) without emitting any bubbles that could give away their location. This unit also limits the diver's depth to 25 feet because of the toxic nature of oxygen under pressure.

Answer 8

it incresses from the pressure of the water abov e the diver