Factors Affecting the Capture Efficiency of a Fume Extraction Torch for Gas Metal Arc Welding

The high deposition rates and temperatures implemented in semi-automatic welding lead to high fume emissions. These fumes have been classified as Group 2B - "possibly carcinogenic" - by the International Agency for Research on Cancer (IARC) and this has led to the implementation of local exhaust ventilation (LEV). The fume extraction torch with LEV integrated into the tool is the most attractive solution but its capture efficiency is often disappointing in practice.
This study assesses the main parameters affecting fume capture efficiency namely extracted flow rate, the position of suction openings, torch angle of inclination, deposition rate, etc. These results provide guidance in fume extraction torch design and data for fixing system objectives. The theoretical velocity induced by suction is estimated from the extracted flow rate and the suction opening position. This is the main design parameter and its value should never be less than 0.25 m/s.