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Posted By Hossam
Hi
quick question..
is a single personal oxygen detector
enough for a man to enter
a confined space that involves
electric and argon welding activity?!
in other words..
a reading of 20.9% for O2
in a place necessarily means
that other toxic or
flammable vabours
for such activity are below permissible limits?
please advise
Hossam
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Posted By Rich Bannister
You need to provide more detail of what you are doing and what kind of confined space.
20.9% O2 does not mean that there are no flammable or toxic vapours.
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Posted By Hossam
thanks for the response Rich
the space is a steel chamber
the activity is electrical and argon welding only
extraction fans provided
and the contractor providing O2 detector claiming that as long as O2 is kept normal it is an indicator that no displacement by other gas is happening.
then what are the multi gas detectors for then?? this is my dispute with him..
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Posted By Tabs
Quick answer: No.
Longer answer needs more information:
You do not say what has been in the space before the welder.
You do not say what is being welded.
You do not say what adjacent processes might contribute to the atmosphere.
You do not say what services are running through the areas (which might get cut or leak).
Etc.
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Posted By Tabs
Our postings crossed.
The O2 indicator tells you one thing only, the presence and concentration of Oxygen.
It does not warn of anything else, full stop
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Posted By Meirion
Hi Hossam,
Only an Oxy sensor on your detector is not adequate. It will inform you that there is adequate Oxygen within the atmosphere within the Confined Space; however some toxic gas, fumes or vapur displace the nitrogen and have little effect on the Oxygen which is not a good thing.
You need to assess the possible toxic gases, fumes or vapour that would reasonably be foreseeable with the Confined Space and ensure that your atmosphere monitor is adequate to detect the presence of these.
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Posted By Flic
You have had an excellent answer from others about the oxygen sensor. I also note that you appear to be planning to do electric arc welding inside a steel structure. This carries a much higher risk of electrocution - the open circuit voltage of welding sets is enough to kill in these circumstances. Unless this is something your company has done before I suggest you seek advice.
Flic
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Posted By Hossam
many thanks for all who advised..
so the conclusion as i undersood is..
The O2 volume in a place might not get affected with the presence of toxic and/or flammable gases.
and so the O2 detector only is not enough for my case as risk assessment mentioned the presence of toxic vabours out of the process and also flammable ones due to oxy/propane heating.
I rejected this detector and asked the contractor for o2+toxic+flammable gases detector instrument.
thanks again
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Posted By dave burrage
Hossam
Consider the relative toxicity of some typical confined space gases e.g. H2S at 700ppm is potentially fatal...so your O2 meter is reading 20.6% which would not be significantly reduced if you also had 700ppm H2S in the area.
ie 700ppm = 0.07%
Rgds
Dave
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Posted By Hossam
Dave
thanks very much..I got it
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