Yes, I know, the dude’s gonna die anyways…

I’m surfing around the Mythbuster’s site on Discovery, because I have a thought that has been needling my brain since Wednesday night. On the last episode, the Mythbusters gang was tossing around the idea that should the air compressor line of a deep-sea diver (Brass helmet type from the mid-century) be cut, the water pressure surrounding his body would force his body up into his helmet. Now, I have to admit, I didn’t actually sit with the fam and watch the whole episode, just catching tidbits here and there, followed by a lengthy discussion after the fact, so I don’t really know all the facts of the experiment.
As I wait for the Mythbuster’s pages to load, the same thought is poking around in my brain, as was on Wednesday. Did they really take all factors into consideration?
The premise is, that with these deep-sea diving suits, an air compressor is used to stablize the pressure INSIDE the suit to compliment the water pressure OUTSIDE the suit, thereby stopping the diver from being deflated while underwater. The myth is that, if the air compressor line is cut, the pressure of the surrounding water will deflate the suit, forcing the body inside up into the brass helmet.
Now, this all makes perfect sense. However, I have that one thought needling around in my head. Would the helmet and hence the suit, not be filled with water pulled into it through the cut hose? And would this not stablize the pressure INSIDE the suit equal the pressure OUTSIDE the suit? You see, the helmet has vents, which would be open under water, allowing the air inside the suit to be released as more compressed air is pumped in. These vents would continue to release air, after the line is cut, thereby causing a vacuum within the suit. This vacuum would draw water into the suit from the cut end of the air line. At least, this is what seems logical to me. I’m certainly not a scientist by any stretch of the imagination, which is why I’m so befuddled I’m sure, but I can’t seem to let it go.
So, wouldn’t the vacuum cause the suit to fill with water, and would that water not equal the pressure of the water on the outside of the suit, thereby stopping the body from being sucked up into the helmet?
What I’m trying to discover, rather unsuccessfully I might add, is whether the line in the final experiment was actually underwater, and if it was actually “cut”, or did they just perform the experiment by turning the valve at the compressor, thereby cutting off the flow of air. All the tidbits I saw in passing were just of the gang shutting the air valve off. This is not a true representation of the myth. And let me tell ya, this Mythbuster’s site is not easy to navigate for information.
And in the end, would I be right? If the hose was cut underwater, would the suit fill, equalizing the pressure and stopping the body from being sucked up into the helmet?
Really, I want them to do the experiment my way if they didn’t already, because the idea of it all is driving me fucking NUTS, and I can’t find the info I’m looking for.



  1. February 7, 2010 at 8:47 pm

    Aren’t their shows fun? I love to do this kind of “true, but so what” thinking. Just like with the myth about being sucked out an airplane window, the human body doesn’t crush down that easily. You might either suffocate, or drown, but the skeleton provides stability nearly equal to the diving helmet itself, especially at the lumbar vertebrae and femur level. To crush the body, you would need enough depth pressure to crush the helmet, and the suits aren’t used at nearly that depth.

    (I found you from the Forums. My latest posts are about home remodeling hell, the spectre of Joni Mitchell, and how brains fill in hearing gaps.)

    • February 8, 2010 at 8:37 am

      I’m also caught in the whole “how much room is really inside those helmets?” thought. I’m hoping they have a do-over show. According to one of my children, they did have a skeleton of sorts inside the body inside the suit, but the helmet filled with body anyway…I really don’t have a lot to go on, other then pure speculation!

  2. gigisanchez said,

    February 8, 2010 at 10:20 pm

    this post makes you sound incredibly intelligent…

  3. gigisanchez said,

    February 9, 2010 at 3:33 pm

    That’s a good bumper sticker -with the AM capitalized. 🙂

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