[Beowulf] HVAC and room cooling...

Jim Lux james.p.lux at jpl.nasa.gov
Sat Jan 31 18:53:27 EST 2004

Found some definitions:
An oxygen-deficient atmosphere means that there is not enough oxygen in the
Normal air is made up of 20.8 percent oxygen.

An oxygen-deficient atmosphere has less than 19.5 percent of oxygen.

 Levels below 10 percent can cause unconsciousness and levels below 8
percent can quickly cause death.

That's probably where Per's 19.5% came from

And, a delightful paragraph from OSHA:
Oxygen deprivation is one form of asphyxiation. While it is desirable to
maintain the atmospheric oxygen level at 21% by volume, the body can
tolerate deviation from this ideal. When the oxygen level falls to 17%, the
first sign of hypoxia is a deterioration to night vision which is not
noticeable until a normal oxygen concentration is restored. Physiologic
effects are increased breathing volume and accelerated heartbeat. Between
14-16% physiologic effects are increased breathing volume, accelerated
heartbeat, very poor muscular coordination, rapid fatigue, and intermittent
respiration. Between 6-10% the effects are nausea, vomiting, inability to
perform, and unconsciousness. Less than 6%, spasmatic breathing, convulsive
movements, and death in minutes.

----- Original Message -----
From: "Pfenniger Daniel" <daniel.pfenniger at obs.unige.ch>
To: "Per Lindstrom" <klamman.gard at telia.com>
Cc: "John Hearns" <john.hearns at clustervision.com>;
<rossini at u.washington.edu>; <beowulf at beowulf.org>
Sent: Saturday, January 31, 2004 1:59 PM
Subject: Re: [Beowulf] HVAC and room cooling...

> Per Lindstrom wrote:
> >
> > Liquid Nitrogen is deadly dangerous as it will shut off the breathing
> > function of the human body when the Oxygen content falls below 19.5 %
> > and thereby causing suffocation.
> >
> Yeah sure, this remind me the joke about dihydrogen oxyd (H2O) deadly
> dangerous when inhaled in too large quantities.
> The quoted 19.5% are probably referring to the human body (blood?)
> concentration, not the inhaled air.  Otherwise most of the people in
> pubs or small rooms would rapidly die as the normal O2 concentration
> in air is 20%

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