Evaluation of the performance of two types of low volume high velocity ventilation systems for the CO2 welding process

Abstract

Aim: Millions of workers worldwide are exposed to the complications of fumes and gases welding process. This study aimed to evaluate the performance of two types of hoods installed on CO2 welding torch in a low volume high velocity (LVHV) ventilation system to control its pollutants. Materials and Methods: Two designs of slots and bell-shaped hoods were designed with an inner diameter of 46 and 37 mm, respectively. To determine the efficiency of the studied hoods, personal sampling at the source of pollutant production (at a distance of 15 cm from the tip of the torch), was performed by the National Institute of Occupational Safety and Health Method No. 7302. The concentration of iron metals, manganese, and total chromium was measured and analyzed when the LVHV ventilation system was on and off. Results: The two designed hoods, showed different efficiencies against the studied metals. The highest efficiency obtained was related to manganese metal in the bell-shaped hood with an average of 84.92%, and the lowest efficiency was related to chromium metal in the slot hood with an average of 13.39%. Optimal exhaust flow rate ventilation obtained for low volume – high-velocity ventilation system was 14 m3/h. Conclusion: In general, the bell-shaped hood with 75.34% efficiency had better performance in eliminating welding fumes than the slot-shaped hood, which is due to the physical form of the hood. Therefore, the shape of the hood, distance of the hood from the point of electric arc and exhaust flow rate at the hood opening, are important factors in the design and efficiency of a low volume - high-velocity ventilation system.

Keywords

• destructive and nondestructive tests
• gas metal arc welding
• low volume-high velocity ventilation
• on-gun extraction