MetFab - Welding Fume Handbook - Flipbook - Page 27
9 Effect of shielding gas: ozone
0.11
0.10
I
0.05
I
Ozone concentration ppm
0.14
I
0.15
0.19
I
0.20
0.09
0
98% Ar/2% O
93% Ar/5% CO/2%O
Ferromaxx®15
80% Ar/20%O
shielding gas
Figure 16: The influence of CO in the shielding gas on exposure to
ozone during arcing MAG welding of mild steel with dip transfer
FCAW
Figure 11 shows the effect of shielding gas on fume emission rate for
FCAW of mild steel.
0.20
I
0.15
I
I
0.05
0.13
0.12
0.11
I
0.10
Ozone OES (15 minute reference period)
0.07
0.12
0.07
0.08
0.05
0.04
0.04
0
92% Ar/8% CO/NO
92% Ar/8% CO
93% Ar/5% CO/2%O
Ferromaxx® 7
Ferromaxx® 15
shielding gas
Figure 17: The effect of shielding gas and mode of transfer on average
exposure to ozone during MAG welding of mild steel (33% duty cycle)
The correlation in Figure 17 between higher carbon dioxide
concentrations in the shielding gas and reduced exposure to
ozone is poor compared to the relationship in Figure 16.
Figure 18 compares ozone production using argon/helium/
carbon dioxide mixtures with an argon/carbon dioxide/
oxygen formulation and an argon-based gas containing nitric
oxide.
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