Английский для сварщиков. Гричин С.В. - 141 стр.

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141
mixtures; welding fume is one of these. It has an occupational exposure limit
but account must also be taken of the exposure limits of the individual
constituents. So, in considering what would be safe exposure levels to
welding fume, not only should exposure be controlled to within the welding
fume limit but also the individual components must be controlled to within
their own limits. The assessment of exposure to fume from welding processes
is covered in EH 54.
Substances may have a maximum exposure limit (MEL) or an
occupation exposure standard (OES).
A MEL is the maximum concentration of an airborne substance to
which people may be exposed under any circumstances. Exposure must be
reduced as far as is reasonably practicable and at least below any MEL.
An OES is the concentration of an airborne substance, for which (according
to current information) there is no evidence that it is likely to cause harm to a
person's health , even if they are exposed day after day. Control is thought to
be adequate if exposure is reduced to or below the standard.
The OESs and the MELs of some of the substances found in welding
fume are listed in Table below; the absence of other substances from this list
does not indicate that they are safe.
Table. Occupational Exposure Limits
8hr TWA
15 min
STEL
Substances Assigned a Maximum Exposure
Limit
Beryllium
0.002
mg/m
3
Cadmium oxide fume (as Cd)
0.025
mg/m
3
Chromium VI compounds (as Cr)
0.05 mg/m
3
Cobalt 0.1 mg/m
3
Nickel (insoluble compounds) 0.5 mg/m
3
Substances Assigned an Occupational
Exposure Standard

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