MetFab - Welding Fume Handbook - Flipbook - Page 11
3 Gases
certain conditions they can cause
asphyxiation. If ventilation is poor,
especially in confined spaces, gas can
build up to dangerous concentrations.
Inhaling such an atmosphere can
cause loss of consciousness in seconds,
because under these conditions the
lungs actually remove oxygen from the
blood.
Argon, which can also be used as a
purging gas to exclude air from the weld
root, is a particular hazard because it is
denser than air and can collect in pits
and other low-lying areas.
Carbon dioxide is said to be a "chemical
asphyxiant" because it is not inert; as
well as lowering the amount of oxygen
available in the atmosphere, it also
hinders the transport of oxygen in
the blood. The levels at which carbon
dioxide causes incapacity are relatively
high, and the risks from its use in
welding are comparable with those
for simple asphyxiants such as argon,
helium and nitrogen.
Carbon monoxide is highly toxic.
Early symptoms of carbon monoxide
poisoning include giddiness, headache
and mental confusion. Chronic
symptoms are not usually significant
at the concentrations normally
encountered in welding.
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