Fume extraction systems – key elements
The most cost-effective way to protect workers from harmful fine dust particles and vapours is to install an extraction system capable of separating out these particles and gases, and then re-circulating the cleaned air back into the workplace. As well as protecting workers from harm and their employers from expensive compensation claims, this approach saves energy and reduces energy costs. It also allows employers to comply with local regulations governing management of hazardous substances.
In choosing an extraction system, it’s important to work with a supplier that has not only the products necessary for your application but also the expertise to advise on a configuration that will best meet your particular requirements. Weller’s Zero-Smog Systems, for example, catch the polluted air right at source, preventing the diffusion of particles and gases. Flux fume contamination of assemblies and the work area is also avoided. A broad range of filters can be combined to provide the best solution to specific filtering requirements.
Fumes can be removed by either tip extraction or volume extraction, depending on the application. Tip extraction systems are suitable for situations involving small working areas, particularly hand soldering. Weller FE (Fume Extraction) soldering irons have a smoke tube integrated into the handle. The tube, which can be retro-fitted, is positioned directly above the joint and collects any fumes produced. Each system supports up to 20 collection points, which can be up to 200 metres apart.
Wider working areas such as solder baths, hot air soldering and micro solders are best handled with a volume extraction system. Weller offers various mobile systems that purify the air at up to eight workstations. These provide an economical way to eliminate polluted process air as they do not need a fixed installation and maintenance requirements are minimal.
BOFA, as another extractor manufacturer, has a similar strategy to Weller in that it offers both tip and volume extraction solutions. These cover applications from solder tip extraction to extraction units with the capacity to handle all manufacturers’ automated soldering systems such as reflow ovens. Pace also offers a range of extractor units. Their line-up comprises five products, from the Arm-Evac 50 to the Arm-Evac 500, with various levels of capability and extraction flow rates. The Arm-Evac 50 is a benchtop unit suitable for powering one or two workstations or extraction points, while the Arm-Evac 500 handles high-performance, cellular manufacturing activities, providing fume extraction for up to six workstations.
All of these solutions’ effectiveness depends on that of their underlying filter technology. Weller’s Zero-Smog Systems are specifically designed for continuous operation in industrial environments. They employ a range of filters for removing small particles, fumes and gases. Fig.2 shows the different filter classes F5, F7, H12 and H13 and the particle sizes they can capture, while Fig. 3 shows the same filter classes against their filtration efficiency.
The Zero-Smog systems, apart from MG 1005, have a three-stage filter system for removing small particles, fumes and gases produced by in different working processes. The hazardous substances are efficiently captured by the nozzle and are absorbed into the filter. Bigger particles are caught in the pre-filter and smaller particles are caught in the HEPA (High Efficiency Particulate Air) filter. For standard applications with a small amount of flux and pollution gases with high solid content, the pre-filter offers filter classes M5 or F7. The HEPA filter is a compact H13 class unit with deposition performance conforming to EN 1822:2009.
The WellerFT wide band gas filter removes fumes and adhesives. It consists of 50 % active carbon and 50 % Chemisorb (potassium permanganate). Harmful gases with a high molecular weight are cleaned by the active carbon. Chemisorb is suitable for absorbing gases of lower molecular weight. Because of its composition, Chemisorb can convert a large number of chemical pollutants (e.g. formaldehyde) by means of molecular modification into non-polluting gases. The end product – clean air – is re-circulated into the workplace.
A gas filter option is also available, but this is intended for extracting adhesive fumes and solvents. For solder baths and automatic soldering, a pre-filter option may be desirable. It acts as a first stage in the filter process, increasing the lifetime of the main filter units.
Managing Solder Fume Extraction. Date published: 24th July 2015 by Farnell