Re: Vacuum Dirgible..

From: Doug Jones (
Date: Mon Apr 17 2000 - 01:52:50 MDT

Spike Jones wrote:
> Speaking of hydrogen, yesterday I was talking to a guy in the Moffett
> blimp hangar with a hydrogen balloon. He had a small H2 cylinder. I
> asked him if someone breathed hydrogen would it make one's
> voice sound funny like helium does? He didnt know, but since
> the reason helium highes ones voice is because its density is
> low, seems like hydrogen would high it even more. But we didnt
> know if it would goof one to breathe hydrogen. We couldnt
> think of any reason why it would, but no one volunteered to
> breathe the stuff. {8^D


Since the flammable limits in air are 4% to 74%, and mixing would vary
from 100% air in the tidal volume to 100% H2 in the last of the
inspiration, all it would take would be one small spark. The
overpressure would instantly burst your lungs, giving a fatal air
embolism. Ugly way to die.

Cyclopropane is sometimes used as an inhalation anesthetic, but its
explosive limits in air are only 2.4 to 10.4 percent- and the
anti-ignition precautions in that application are draconian.

That said, hydrogen's solubility is like that of helium, and it is
sometimes used in deep-sea breathing mixtures because it actually has a
slight narcotic effect. This is used to reduce the high pressure nervous
syndrome of parkinson's-like tremors caused by helium at depths beond
800 FSW. At sea level, hydrogen is physiologically inert.

Doug Jones
Rocket Plumber, XCOR Aerospace

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