On Tue, 03 May 2005 09:08:50 +0200, Eric Smith <eric at brouhaha.com> wrote: It was banned by international treaty many years ago, although some countries were dragging their feet about implementing it. There was a heated discussion about how a theoretical environmental problem (after all, the Halon was not supposed to be released unless there was a real fire) overruled a real danger to human life (replacing Halon with CO2 poses a great risk to anybody who does not get out before it is released). -- Bj?rn

Paul Koning wrote: I'm sure it is. Even allowing for the fact that halon 1301 (or whichever was the commonly used one) is heavier than air and will therefore sink, I don't believe that a concentration of 5% by volume (presumably calculated over the whole room's volume) is going to become much high enough to displace enough oxygen to prevent combustion. (Especially since the sudden inrush of gas plus the presumed pre-existing combustion will both have caused considerable air currents and hence mixing). Halon functions by interfering with the actual combustion. In the presence of combustion (or presumably, just at elevated temperatures) the halon reacts with oxygen, so at the actual flame (and nowhere else) the oxygen is consumed and no longer available to feed the fire. Antonio -- --------------- Antonio Carlini arcarlini at iee.org

Brad> "Antonio Carlini" wrote: Brad> I think the 'problem' may be that because it's heavier than air Brad> it can displace all the air in your lungs. Not the room, Brad> however. Brad> That's just what I was told, and did witness, with refrigerant. Brad> (and why I'd heed the advice to hold your breath :-) Brad> but to be honest, I have no idea if this is actually true. I very much doubt it. The story you quoted doesn't seem to have any connection with physics as I know it. paul

Brad wrote: Like argon, for instance? Argon is heavier than "air", and for that matter heavier than O2, N2, and almost as heavy as CO2. The earth's atmosphere contains about 1% Argon. Since the atmosphere is about 80km tall, obviously there must not be anything but argon down here in the bottom 800m for us to breathe. Just like the claim that a room containing a few percent of halon will have no O2 near the floor.

Tom Jennings wrote: So where does the FART layer go?

On Wed, 4 May 2005, woodelf wrote: Texas.

Then we'd die from all that carbon dioxide and from accumulation of (as Eric mentioned) heavy minor components like argon. The killer gases kill not because of their weight, but their chemical effect on the body (mustard gases are corrosive, carbon monoxide binds tightly to haemoglobin, etc.). If you're cycling air normally, heavier air components don't stay. You have a certain "dead" capacity that is not routinely exchanged with breaths but even this is not a fixed, unchanging airspace with a constant composition. Inhaling a 100% argon atmosphere kills you because there's no oxygen in it, not because the argon itself does something. But if you got out into room air, you'd exchange out the argon (assuming you were still breathing), since the argon is inert and doesn't react with your tissues. -- ---------------------------------- personal: http://www.armory.com/~spectre/ -- Cameron Kaiser, Floodgap Systems Ltd * So. Calif., USA * ckaiser at floodgap.com -- The faster we go, the rounder we get. -- The Grateful Dead, on relativity --

Rumor has it that Brad Parker may have mentioned these words: It sounds like you're assuming a cumulative effect -- if that was the case, we'd never be able to get the CO2 [which is heavier than air] out of our lungs! IANAD, but I would think that (at least in healthy people) the expulsion volume to total volume ratio of the lungs is rather high (60-70% maybe?) - and with the amount of air turbulence created during exhalation a lot of the argon/CO2/[insert heavy gas here] would be expelled. Once you breathe back in, as long as there's enough O2 to sustain life (and a low enough concentration of other molecules which would bind to hemoglobin quicker, say CO) you should be fine. Otherwise, once anyone caught a bit of pneumonia, they'd be dead. Mucus is one heckuva lot heavier and more dense than argon or CO2! In the example you gave, I would think the freon would knock him out a lot faster than the lack of O2 -- I've smelled it a few times, and I liken it to the CS gas I had to breathe in the US Army during boot camp -- nasty stuff. Even lighter than air inert gasses (helium) can be bad for you in high enough concentrations, if they still displace enough O2. You'd just have to climb a ladder instead of lay on the floor to be susceptible, tho. ;-) Very true! Laterz, Roger "Merch" Merchberger -- Roger "Merch" Merchberger -- SysAdmin, Iceberg Computers zmerch at 30below.com What do you do when Life gives you lemons, and you don't *like* lemonade?????????????

Brad Parker wrote: You sink :-) Seriously, I don't see what "bad" things might happen. You should be able to exhale in the usual way. I do not think that exhaling depends on the gas inside your lungs being heavier than air - just on you muscles' ability to push the gas out. I've not tried this (for significant volumes of gas) so don't take my word for it :-) Antonio -- --------------- Antonio Carlini arcarlini at iee.org

der> "Less air" for what value of "air"? What the body wants, as I der> understand it, is a partial pressure of oxygen at least vaguely der> equal to that in the air it's used to. On airplanes, this is der> done by using a gas mixture (proportionately) richer in oxygen der> than air, at a lower pressure. Not true, unless you're thinking about fighter planes. Unpressurized planes (small planes) simply have the ambient air inside. Pressurized planes (airliners) compress the outside air roughly to the pressure that prevails around 8000 feet or so. It's still plain old air, 21 percent oxygen. Moderately healthy humans function fine up to about 10,000 feet, less so as you go up from there. This is why aviation rules allow pilots to fly unpressurized planes without restriction up to 10,000 feet, but require supplemental oxygen if they stay above 10k for more than 30 minutes (or above 14k for any time). Needless to say, mountain dwellers are more tolerant than that. paul

On Wed, 4 May 2005, Paul Koning wrote: I spent a month at 12,000 feet in Cuzco, Peru. It took a couple days to get acclimated (chewing coca leaves would've reduced this time). After the initial queasiness passed, it was just a matter of conditioning to get used to having less oxygen. When I got back home I felt great :) -- Sellam Ismail Vintage Computer Festival ------------------------------------------------------------------------------ International Man of Intrigue and Danger http://www.vintage.org [ Old computing resources for business || Buy/Sell/Trade Vintage Computers ] [ and academia at www.VintageTech.com || at http://marketplace.vintage.org ]

On Wed, 4 May 2005, Jim Leonard wrote: All I found was a copy of Programming the IBM 360 (Spanish edition) in a miscellaneous shop (yes, I bought it :) I also discovered the Quipu, which is what the Inca's used to store information. I wrote a paper on it: http://www.vintage.org/content.php?id=002 -- Sellam Ismail Vintage Computer Festival ------------------------------------------------------------------------------ International Man of Intrigue and Danger http://www.vintage.org [ Old computing resources for business || Buy/Sell/Trade Vintage Computers ] [ and academia at www.VintageTech.com || at http://marketplace.vintage.org ]