: Fire prevention by partial deoxygenation of air
Russell McMahon email (remove spam text)
>> Wood stops burning when the oxygen content falls to 17% and plastic
>> cables between 16 to 17%
>> At 15% oxygen, it's safe for humans to enter.
> So the idea is to hold the oxygen content within that 1% band?
They really mean "A level of 15% is acceptable for fire prevention, so
that's what we use, and it is safe for people."
In fact, levels BELOW 15% are also safe for people.
Atmospheric pressure and, consequently, Oxygen partial pressures,
halve every 14,000 feet or so.
So a reduction to about 11% O2 at sea level is equivalent to an
altitude of 14,000 feet. Most people would certainly notice the
difference by that level, but its still livable and breathable by
most. Only people with medical problems couldn't handle it. Even
Everest base camp at 20,000+ feet is acceptable for all with normal
abilities, albeit with noticeable affects. It's the starting point for
acclimatisation for low Oxygen regimes.
If their claims are correct then it would sound like a wood fire is
not achievable above about 6000 feet. Sounds wrong.
Quick check. Someone living above or preferably well above 6000 feet
please tell us if you can use matches successfully :-)
See also: www.piclist.com/techref/index.htm?key=fire+prevention
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