Welding produces welding gases and welding fumes that are harmful to the health of your employees. The law stipulates that the limit value (formerly maximum acceptable concentration or MAC value) of welding fumes per 8-hour working day is 1mg per m3. A good extraction system is therefore of great importance.
Welding fume extraction can be roughly divided into point extraction and spatial extraction. With point extraction, also known as source extraction, the welding gases and fumes are extracted directly at the source. This prevents the harmful gases from spreading further in the room. With spatial extraction, the entire space is ventilated. Spatial extraction is usually chosen when point extraction is not possible.
Spot or source extraction involves the use of stationary (centrally or locally located) units or mobile units that tackle the problem where it arises. Source extraction exists in the form of extraction arms that can be flexibly adjusted to extract welding fumes close to the welding point and grinding, cutting and welding tables with bottom extraction.
When extracting welding fumes by means of a mixing system, the mixing unit at the top of the hall moves so much air that no welding fume blanket can form. The mixing ensures an evenly distributed and very low (max. 1 mg/m3) concentration of welding fumes throughout the hall. By additionally filtering and/or changing the air, the required low concentration remains below the legally required limit value.
When extracting welding fumes by means of a push-pull system, clean air is blown into the hall through a blow-in channel. The clean air drives the polluted air to the extraction grille, after which the air is filtered by a filter box. The filtered air is blown back into the hall and the process begins again. The legally required part of 1/3rd refreshment can be achieved with, for example, roof fans.
In a central extraction system, several extraction arms and extraction units are connected to one filter box. This can offer advantages in terms of maintenance, (installation and/or maintenance) costs and flexibility.