MovieChat Forums > Sphere (1998) Discussion > Can anyone explain 'decompression' to me...

Can anyone explain 'decompression' to me?


Since this is a fictional movie I'm not sure if it's true or not. But I'm assuming decompression exists? If so, how long do you have to spend decompressing? They mention that you have to not eat for a couple hours, is that true? What happens if you do eat? What happens if you just popped up from under the surface without decompressing? Would you really explode? How does this decompress business work anyways? The character didn't feel any different when they were at the bottom of the sea. If you have to decompress how come there's no compressing process to begin with.

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Decompression is your body returning to surface pressure after compression, such as in a deck decompression chamber. Regarding diving, this movie is a load of nonsense really.

Basically a saturation diver is compressed to the pressure he works at. 10 metres of water = 1 bar so at 100m it's 11 as you include the atmosphere above water all the way to space. It might take several hours to compress to the working depth. During compression your tissues are saturated in gas hence the name. Inside a DDC when gas is squeezed in it simulates the pressure at depth and adjusts you accordingly. You live at this working pressure and travel to working depth at pressure in a bell. When the bell reaches the working depth the pressure inside and outside are equal and you can leave the bell to work. The bell door usually pops open. As sat divers remain at pressure in the bell and on the surface chamber they can continually ascend and descend from depth and decompress once, at the end. The deeper the longer it takes for the body to return to normal.

As for the effects, it depends on the rate of pressure change. Surfacing to quickly from say 50m in a few minutes will usually result in the bends. As our tissues are mostly water, when we are compressed then decompressed too quickly our body reacts like opening a bottle of coke too quickly. Gas escapes from a pressurised liquid and those bubbles in our body causes the bends. Open the bottle slowly(like a controlled decompression) will result in no bubbles so you would be fine.

Surfacing in a fraction of a second from great depth would result in explosive decompression. This has happened, think a diving bell popping off a pressurised chamber. The result is truely horrific, you would explode, it has happened before to sat divers.

Just quickly...

You do compress to begin with.
The duration of decompression and compression relates to depth, the deeper the longer for both.

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basically if you're diving the 50m range, stop a few minutes every 10-15 meters and never ascend faster than bubbles.

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