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This fire extinguishent reduces the atmospheric oxygen concentration to less than 15% which is 'acceptable for human exposure over a short period of time'. All of the information I have found says much the same thing without being specific; does anyone know what the short period of time might be?
LB
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Rank: Forum user
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Not sure where they get that less than 15% O2 concentration is acceptable for human exposure as you will see from the table below
Percent Oxygen v Health Effects
17%
Night vision reduced Increased breathing volume Accelerated heartbeat
16%
Dizziness Reaction time for new tasks is doubled
15%
Poor judgment Poor coordination Abnormal fatigue upon exertion Loss of muscle control
10-12%
Very faulty judgment Very poor muscular coordination Loss of consciousness
8-10%
Nausea Vomiting Coma
<8%
Permanent brain damage

<6%
Spasmodic breathing Convulsive movements Death in 5-8 minutes
Cheers Phil
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Rank: Super forum user
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Thanks, Phil
That is the information I am more familiar with; I guess it comes down to exposure time, which is the root of my query.
LB
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Rank: Super forum user 
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Some years ago I volunteered to stay in a compartment during a demo of one of these extinguishant gases in action. I do not recall the actual product (quite possibly argonite) but I'm still here to tell the tale!
LB, exposure time is the important missing bit and as I understand it, the whole concept of these gases is to knock down flames and allow escape, hopefully preventing re-ignition.
Hopefully somebody else here can give further info.
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Rank: Forum user
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Hi LB,
I presume that by the nature of the way the aragonite works that the change from ~21% to "less than 15%" would need to be almost instant to control the fire. I would be also interested in how much less than 15% the atmosphere is changed to, i.e is it 14.5% or 3%?
Distances to exits would be the telling answer i suppose, especially if the exits are far away, or you turn the wrong way due to hypoxic confusion as demonstrated in the 12 - 15% band above, however if you bump your head whilst escaping, and collapse, how long after the discharge is the room atmosphere back to near the 21% that we all know and love.
More questions than answers for you I'm afraid, but a great topic!!
Cheers
Phil
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Rank: Forum user
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""Argonite extinguishes by means of reducing the oxygen content within a room to the point at which fire can no longer burn, but without compromising the safety of individuals present. There are no toxicological factors associated with the use of Argonite. Argonite will not decompose or produce any by-products when exposed to a flame from a fire condition.
Most Argonite systems are designed to extinguish fires with a minimum agent concentration of 37.9% achieved within one minute.
This results in extinguishment of the fire and an oxygen concentration of 13%.""
The above is an extract from their site and MSDS, they seem to put the "respirable atmosphere" after actuation of the product of 13%, so it would definitely come down to distance to exit points. Would we be happy having lone workers in rooms that were protected by Argonite?
In effect it makes it a confined space by way of none respirable (i.e not above 19.5% oxygen as we and the regs like) atmosphere. id better shut up as I think i may have opened a can of worms!!!
Cheers
Phil
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Rank: Super forum user
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According to one well known website 'Argonite' is a brand name and registered trademark for a mixture of 50% argon and 50% nitrogen used as an inert gas in gaseous fire suppression systems.
As an aside, shortly after joining HSE in 1977 I observed a court case which stemmed from an investigation by my boss of the death of a fitter from asphyxiation in a sub-surface valve pit at an oil platform construction yard in Northern Scotland. As there had been a leak of argon (one of the gases distributed in underground pipes around the yard for welding processes) from a valve, the atmosphere within the pit - a confined space - had become flooded with argon. Though the case was defended, the prosecution was successful as the sheriff agreed from the evidence that the firm had not taken sufficient precautions to ensure the man's safety for entering and working in the pit. However, there's probably a considerable difference between a valve pit unknowingly flooded with argon gas and workplaces where Argonite may be introduced as a fire suppressant under controlled conditions.
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Rank: Super forum user
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Thanks guys
There is a double knock alarm system and people have 30 seconds after the second knock to leave the area before the gas is discharged. Therefore, the chance of anyone being in the area to be possibly asphyxiated is, I hope, remote. However, I have been asked to assess the risk to some helpful soul who remains behind despite the procedures to the contrary!
LB
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Rank: Super forum user
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HeO2 wrote:Not sure where they get that less than 15% O2 concentration is acceptable for human exposure as you will see from the table below
Percent Oxygen v Health Effects
17%
Night vision reduced Increased breathing volume Accelerated heartbeat
16%
Dizziness Reaction time for new tasks is doubled
15%
Poor judgment Poor coordination Abnormal fatigue upon exertion Loss of muscle control
10-12%
Very faulty judgment Very poor muscular coordination Loss of consciousness
8-10%
Nausea Vomiting Coma
<8%
Permanent brain damage

<6%
Spasmodic breathing Convulsive movements Death in 5-8 minutes
Cheers Phil I always take these sorts of figures with a huge pinch of salt. First of all, they are reliant on being in that concentration for long enough for symptoms to appear. One lungful of a very low oxygen level is believed to be fatal, without symptoms. The other reason I am sceptical about the lower end of the range is to ask - how did they get this data? How reliable is it likely to be? Go to this page and choose 'decompression chamber' to see Michael Portillo experience a low oxygen environment http://www.bbc.co.uk/sn/...x/executions/near_death/
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