how to produce breathable oxygen

The cheapest way is to grow weeds.

Manganese isn't the nicest stuff to have hanging around.

tell that to a guy trapped in an underground mine when rescuers are 48 hours away and he has only 3 hours oxygen ?

Oh, look. Additional information not contained in the original post. How quaint.

Expose a plant to bright sunlight.

It really depends on the application. Bottled or on site-produced oxygen is not going to be very cost effective compared to standard or filtered ventilation. Additionally bottled or on site-produced oxygen may not be practical if there is no way to regulate the waste gas buildup (eg- carbon dioxide from breathing, carbon monoxide from a generator producing oxygen, etc) or no way to guarantee on demand supply (eg- power failure of oxygen generator, damage to critical oxygen generator system, etc).

My personal preference (if this is, say a mining application) is bottled oxygen and filtered masks, and if possible a fully-stocked safe room. When you need it in an emergency you want to be sure it will work.

Can you describe your application in more depth please.

thanks Jack

i have used BOC Gases 420 medical dry air for confined spaces work which gave me around 6 hours supply per G size bottle per man into a face mask ( without a hospital type accumulator to smooth out supply/demand rate ) , they would last alot longer for a man at rest when a diaghram accumulator is used

mains powered oxygen generators use membrane separation to obtain high O2 concentrations , but if the outside air is toxic in a coal mine or from a volcanic eruption then those machines wont be a safe option.

If bottled gas was used in a rescue pod then scrubbers would still be required to take out carbon dioxide and monoxide, a plus is that at least medical air is not explosive if someone turns on a mobile phone or radio ( or takes a photo with a flash camera ) , i will point out here to readers that Medical Oxygen is a different product from Medical air , medical oxygen is higher purity and could be explosive if ignition source is present

as a downside oxygen candles or H2O2 /MNO2 might produce 95 % O2 which does have risk of explosion if ignition source is present

Now to give more detail about the application ........ i made reference to mining use but i want to now also extend that to identify if they can be a safe way to survive the effects of volcanic ash and gas flows from an eruption .

whether the application is for use in a mining rescue pod or an above ground home based oxygen tent , at call oxygen that can be stored for long periods is what i am looking for

there are at least 3 - 4 manufacturers of oxygen candles around the world , they retail at around $ 750 AUD each for 100 man hours O2 for that brand , but thats not practical if you want to create a safe room for 20 people during a volcanic eruption that lasts for month.

must be a better way ?

I am guessing this is in response to the Chilean volcanic ash cloud covering parts of Australia and seriously effecting air travel, but not really posing a serious danger to people on the ground.

Link

Lets keep it practical. Light ash cover can be combated by simply staying indoors or walking around outside with a simple mask (think of it as heavy air pollution). Heavier and more prolonged ash cover can be combated by staying indoors and simply filtering the outside air.

Anything more prolonged or dangerous would require more drastic methods (like bottled O2 or similar), but you would need to be near an active volcano for this to really come into effect (this is especially the case for toxic gasses which don't travel nearly as far as ash clouds), and should already have been given ample warning to evacuate if such a situation arose (hence the people in the effected area are already out of harms way, so no problem).

Just out if interest (and from memory) we have about 50 volcanoes in Auckland (in various states of dormancy), the closest one to me is about 300m away.

My main focus is survival in the mining environment during a wall collapse or fire . however the Chilean volcano and ash cloud did trigger thoughts about engineered responses to it as well , as i did have friends there recently who were stranded due to restricted jet flights , they are not land locked and have escape options though.

I think it worth considering the design elements of rescue equipment for areas at risk such as the "pacific rim of fire", volcanos can pump out alot of toxic gases such as flourine , sulfur , carbon dioxide and carbon monoxide which will snuff out human life as surely as being hit by larvae or rock projectiles within the (unquantifiable) range of any future eruption , a respirator is useless in that environment if there is no oxygen present even if there were respirator cartridges that could filter out all those toxins successfully , so the obvious solution would be oxygen generated by chemical reactions .

Commercially available Oxygen candles do work and can have a shelf life of up to 20 years , there has been two reported deaths on submarines from these products however , probably caused by improper storage and contamination from _ Oil_ being spilt onto the candle which caused an explosion. the oxygen emitted will also be at up to 300 celcius , so there is risk of burns to the respiratory passage if they are used in small confined spaces.

A reasonable alternative might be Hydrogen Peroxide and manganese dioxide , they dont produce the same heat , it is cheap to produce , but i dont know of any health risks from the reaction or exposure to the stored ingredients..........

So we have applications for oxygen producing products , i am sure there will be other means of doing it , just need some more chemical engineers to comment here

cheers

Can somebody help me out with something?

Headsup implies 100 liters of O₂ is sufficient for 20 hours for one person. Or, am I misreading that part of the original post?

Respiratory minute volume for a man is about 8 liters (of air) at rest, and as high as 60 liters at moderate exertion. Plain air is about 20% O₂. So, let us say a man trapped in a mine, at rest but understandably anxious has a respiratory minute volume of about 12 liters. 20% of 12 liters = 2.4 liters of O₂ per minute, or about 140 liters of O₂ per hour.

thanks doorman

i used figures from a supplier of O2 candles but your figures are an internationally recognised standard ? .........

i will use the 140 litres / minute figure ( for adults at rest - light physical activity )

for an enclosed space such as mining shelter or oxygen tent above ground , the figure is going to be higher when a supply mask is not being used or if leakage occurs

lithium oxide CO2 ( and CO ) scrubbers could swing the maths in a more favourable direction.

sorry . typo above 140 litres / hour

I am not certain my "...figures are an internationally recognised standard". This sort of biology is not really one of my strong suits.

The figure of 100 liters per 20 hours just sounded pretty low. As with anything, this should be investigated and confirmed.

Something like an oxygen candle is the emergency backup of the International Space Station. This Wiki article tells a little bit about it.

Your best bet would be move away from LA. Mountain air doesn't require all that chemistry to get breathable air.