MetFab - Welding Fume Handbook - Flipbook - Page 33
0.12
0.06
I
0.04
I
0.06
0.019
I
0.02
0.073
I
0.08
0.101
I
0.10
I
Exposure to ozone during arcing ppm
9 Effect of shielding gas: ozone
0
Argon
Argon/1%N
Argon/2%N
79%Ar/20%He/1%N
shielding gas
Figure 25: The effect of shielding gas formation on ozone
generation during TIG welding of duplex stainless steel
FCAW
1.2
I
1.0
I
0.8
I
0.6
I
0.4
I
0.2
I
Ozone concentration ppm
Figure 26 shows ozone concentrations measured at a point
next to the arc over a period of 30 seconds. The arc was
alight for only part of this time; the graph shows that ozone
concentration rises quickly when the arc is struck, and decays
quickly once the arc is extinguished. The beneficial effect of
carbon dioxide in reducing ozone levels can again be seen.
0
35%Ar/50%He/15%CO
CO
I
10
I
20
I
30
I
40
shielding gas
I
250
I
60
I
70
Figure 26: The effect of shielding gas on ozone concentration in the
proximate zone during FCAW of stainless steel
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