Why dont seals get the bends??

[Warewolf50]

I think the original poster was interested in seals, the sea mammals rather than human military version.

My guess would be that seals don't get the bends because they're diving on a single breath of air rather than continually breathing underwater. There's no continual influx of new gases at depth if you're operating on a single breath of air, so there's less gas in total that can be dissolved in the blood and tissues.

BJJB

I think that would be correct because people who do freediving, which is diving really deep wiht no equipment. The record for deepest dive recorder is 230', and once again that is without any scuba equipment. When these people ascend they do it quickly soo i guess it is the multiple breath thing.

[SAW]

Free dive to 230'?

[Destructo6]

Lots of the combat diving is done at rather shallow depths.

BUD/s dive phase (and AT) includes a significant focus on proper ascents. The big tower at NavSpecWarCen is a dive tower (filled with water with a Sub lockout chamber at the bottom), used to practice such ascents.

[Kevmaster]

I think the original poster was interested in seals, the sea mammals rather than human military version.

My guess would be that seals don't get the bends because they're diving on a single breath of air rather than continually breathing underwater. There's no continual influx of new gases at depth if you're operating on a single breath of air, so there's less gas in total that can be dissolved in the blood and tissues.

BJJB

95% sure thats the right answer.

[Gitaroo Man]

i would lay my bets on this as well.


the bends, aka nitrogen narcosis (aka, getting "narc'd") is the buildup of nitrogen bubbles in the blood stream.

they would need barely any decompession time, just enough to catch their breath, empty their lungs, and go at it again

Uhhh, The Bends is completely different from Nirogen Narcosis. The Bends is decompression sickness where you get dissolved nitrogen in your blood and then they form bubbles. Nitrogen Narcosis is your body getting excess nitrogen, at depths below 130 feet I believe, and you get a drunk like feeling. They are very, very different.

[Dubstar112]

There is no intake of air under water so there is no atmosphere change inside the lungs. (that makes sense right?)

SCUBA, the deeper you go, more air is used because it gets compressed. Roughly your lungs stay the same size, but since the air is much more dense at depth you take in more overall to do the same work. I help out with a family run SCUBA shop both commercial/industrial and "pleasure seeking".

We also have a Decompression chamber, c'mon Ill give you a free ride

[TheTramp]

the bends is caused by the nitrogen used to dilute the oxygen in a scuba tank.

SCUBA tanks are filled with filtered air. There is no diluting of anything unless you're talking about the specilty mixes for deep/extended dives.

With that said, it's funny to listen to the guys using a hydrox mix speak into their helmet mikes. A bunch of burly underwater construction workers who all sound like different versions of the chipmunks

[MantisMag]

hydrox mix?


i think you mean heliox. i really didn't think many people used it. i knew it was out there. just didn't think it was commonly used.

http://en.wikipedia.org/wiki/Decompression_sickness

i looked it up. it seems the main factor is that you continue to breathe. even snorkelers can get the bends if they make several dives in succession.


i also found out that nitrox, the nitrogen oxygen mix, is actually used to decrease the risk of decompression sickness. there's less nitrogen in nitrox than compressed air. however even heliox can give you the bends if you dive deep and long enough. decompression time is significantly reduced though.

[TheTramp]

hydrox mix?


i think you mean heliox. i really didn't think many people used it. i knew it was out there. just didn't think it was commonly used.

http://en.wikipedia.org/wiki/Decompression_sickness

i looked it up. it seems the main factor is that you continue to breathe. even snorkelers can get the bends if they make several dives in succession.


i also found out that nitrox, the nitrogen oxygen mix, is actually used to decrease the risk of decompression sickness. there's less nitrogen in nitrox than compressed air. however even heliox can give you the bends if you dive deep and long enough. decompression time is significantly reduced though.

You're right. I ment heliox. Hydrox would be hydrogen and oxygen and wouldn't make a very good dive gas :) And it's not common outside of comercial diving (underwater welders, etc).

There's nothing that will allow you to stay at pressure indeffinatly without ever needing to decompress. Just stuff that makes the whole prosess less of a hassle (ie less decompression time or more time on bottom without having to use the chamber).

[Dubstar112]

We use nitrox(Mixed by my uncle). For average every day wreck diving, its more a luxury though. Typically up to 100 feet in the st lawrence.

[gc82000]

The Bends as I learned was the collapse of a lung/s from rising too quickly froma depth greater then 50 ft. And I know free divers can get this, especially those who are trying to fish in the open water. An instructor told my free diving class about a freind of his who died from the Bends after going down and trying to come up too fast.

[RobAGD]

Ok Google is your friend

http://science.howstuffworks.com/question101.htm

SCUBA stands for self-contained underwater breathing apparatus. When using SCUBA equipment, a diver breathes from a tank that holds highly compressed air.

SCUBA diving is different from holding your breath and diving, and to understand the difference you need to understand the incredible pressures that a diver's body experiences. When we are living on dry land at sea level, the air around us has a pressure of 14.7 PSI (pounds per square inch), or 1 atmosphere. That is a "normal pressure" for our bodies. Because water is so heavy compared to air, it does not take much water to exert a lot of pressure. For example, a 1-inch by 1-inch column of water 33 feet high exerts another 14.7 PSI.

If you hold your breath and dive down 33 feet (10 meters), therefore, your lungs actually contract in size by a factor of two. They have to -- there is twice as much pressure around the air in your lungs, so they contract. When you rise back up the air expands again, so your lungs return to normal size.

When you breathe from a SCUBA tank, the air coming out of the tank actually has the same pressure as the pressure that the water is exerting. It has to, or it won't come out of the tank. Therefore, when SCUBA diving, the air in your lungs at a 33-foot depth has twice the pressure of air on land. At 66 feet, it has three times the pressure. At 99 feet, it has four times the pressure, and so on.

When high-pressure gases in the air come in contact with water, they dissolve into the water. This is how carbonated beverages are made. To make carbonated water, water is exposed to high-pressure carbon dioxide gas, and the gas dissolves into the water. We all know what happens when you release the pressure in a bottle of soda -- bubbles suddenly start rising. The gas dissolved in the water at high-pressure comes out of the liquid when the pressure is released, and we see it as bubbles.

If a SCUBA diver stays under water, say at a depth of 100 feet (about 30 meters), for a certain period of time, some amount of nitrogen from the air will dissolve in the water in his or her body. If the diver were to swim quickly to the surface, it is just like uncorking a bottle of soda -- the gas is released. This can cause a very painful condition, and it is sometimes fatal.

To avoid the effects of quick decompression, the diver must rise slowly and/or make intermittent stops on the way up (called "decompression stops") so that the gas can come out of solution slowly. If the diver does rise too fast, the only cure is to enter a pressurized chamber in which the air pressure matches the pressure at depth (breathing 100-percent oxygen on the way to the chamber also helps). Then, the pressure is released slowly.

Decompression sickness, also known as the bends, is one danger of diving. Other dangers include nitrogen narcosis, oxygen toxicity and simple drowning (if you run out of air before making it back to the surface). If the diver decompresses properly, remains at "recreational depths" (less than 100 feet or so), and is careful about the air supply, the dangers can be largely eliminated. Proper training, good equipment and careful execution are the keys to safe diving.


-=-=-=-

So think if this, that reg on a scuba tank is allowing enough air into your lungs to re inflate them :) So at some point you coudl have several hundred punds of air entering your lungs. I had fun one summer taking a 15ft pole to the bottom of the deep end of the pool, and trying to snorkel with it. At 15ft is a damn bastard to breath and your only getting 7psi more pressure at that depth.

What fun

-R

[Alpha]

Okay.. before i can answer with all my SCUBA knowledge, I need a defenition of "seal" are you talking NAVY SEALS or MArine seals?

Remember Clarification = good.

LOL, I thought they were talking about Navy SEALS. Wait hte Marine Corps doesn't have SEALS.. [/Sarcasm]

[TheTramp]

The Bends as I learned was the collapse of a lung/s from rising too quickly froma depth greater then 50 ft. And I know free divers can get this, especially those who are trying to fish in the open water. An instructor told my free diving class about a freind of his who died from the Bends after going down and trying to come up too fast.

If you rise to quickly your lungs could explode due to the air within them expanding dramatically. It's more likely that your lungs would simply be damaged and then you breathe out the extra volume.

Breathing in and out as you ascend slowly fixed this problem.


This short answer on the bends is: At depth N2 dissolves in your blood to a much higher concentration that at sea level. If you do not rise slowly while breathing in and out (so the N2 has somewhere to go) the N2 will form bubbles in your blood with at best move to the joints and cause excruciating pain and at worse get into your head and cause massive brain damage while also ruining your lungs.