A welding fume filter removes the particles generated during welding from the extracted air. To do this, the welding fumes are captured as close as possible to the source and directed to the filter system. The filter alone is not the only factor determining effectiveness: According to the DGUV, the overall effectiveness of an extraction and filtration system is determined by the capture efficiency and the separation efficiency.

The closer welding fumes are captured at the source, the less likely they are to enter the employees’ breathing zone and the workshop air. The DGUV therefore identifies extraction at the source as the primary technical measure. For this purpose, systems such as torch-integrated captures, extraction arms, welding tables, or extraction hoods can be used.

The substances present in welding fumes depend, among other things, on the material and the welding process. When welding materials containing chromium and nickel, for example, chromium(VI) and nickel compounds may be of concern. Studies by the DGUV Institute for Occupational Safety and Health identify chromium(VI), nickel, and manganese, among others, as relevant exposure parameters for chromium-nickel steels.

Welding fume extraction class W3 designates appropriately tested welding fume extraction units with an extraction efficiency of at least 99%. The IFA tests and certifies such units in accordance with DIN EN ISO 21904-1 and -2 up to a maximum extraction flow rate of 2,500 m³/h. Devices that pass testing receive the DGUV Test mark “Tested for Hazardous Substances—Welding Fume Separation Class W3” and are included in the corresponding IFA approved list.

The W3 designation is particularly relevant for air recirculation in the case of welding fumes containing KMR substances when exhaust air discharge is not possible, such as at mobile workstations. For stationary extraction and filtration systems, however, there is currently no generally defined procedure for approval under Section 10(2) of the GefStoffV.

Whether recirculation of air is permitted depends, among other things, on the hazardous substances present and the extraction technology used. If the welding fumes contain Carcinogenic, Mutagenic, or Reprotoxic (CMR) substances in Category 1A or 1B, recirculating the extracted air back into the work area is generally not permitted. Whenever possible, the air should be vented to the outside, particularly at stationary workstations.

If exhaust ventilation is not possible—for example, at mobile workstations—a welding fume extraction unit that has been tested in accordance with DIN EN ISO 21904-1 and -2, is approved, and is marked “W3” may be used under the conditions specified in TRGS 528. However, even the use of an approved unit does not replace the risk assessment or the evaluation of actual exposure in the workplace.

According to the IFA, there is currently no generally defined procedure for obtaining approval under Section 10(2) of the GefStoffV for stationary extraction and filtration systems. For CMR substances, therefore, exhaust air must generally be vented to the outside; approval on a case-by-case basis by the competent regulatory authority is possible.

The right extraction solution depends on several factors, including the welding process, the material, the hazardous substances produced, the required airflow rate, and the type of capture. The position of the capture element is also crucial. We’d be happy to advise you on selecting and designing the right welding fume filter for your operation. Contact us at vertrieb@absaugwerk.de.

Mobile welding fume filters are particularly well-suited for changing workstations and can be used, for example, with a movable extraction arm. Stationary systems, on the other hand, are ideal for fixed workstations, machines, or centralized extraction solutions. The appropriate type of extraction depends on the specific welding process and workstation.