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All forms of welding create fumes that pose exposure hazards. You can greatly reduce weld fume exposure levels by properly ventilating the workspace. Don’t assume that using a fan, opening a window, or even welding outside will adequately protect your welders. The American Conference of Governmental Industrial Hygienists (ACGIH) prefers fume extractors (also called dust or fume collectors) over natural ventilation for their ability to capture weld fumes near the source, before contaminants are dispersed throughout the facility.
While each welding facility is unique, the following questions will help you select the most appropriate weld fume extraction system for your operation.
First, you need to understand the combustion risks present in your operation by analyzing your materials and process. You’ll find guidance for this analysis in Standards 652 and 484 of the National Fire Protection Association (NFPA). Many local governments are making these standards mandatory, and OSHA inspectors are known to enforce them as well. NFPA Standard 652 sets a deadline of September 7, 2020 to complete a dust hazard analysis and have a combustible dust mitigation plan in place. Once you identify your hazards, you can develop a fume extraction strategy specifically for your facility.
Next, you need to determine the duty cycle of your operation and the volume of particulates your fume extractor will need to handle. Do you operate 24/7 or weld for eight straight hours during a normal workday? If so, you will likely produce a higher level of weld fume particulate and want to consider fume extractors that run continuously, have self-cleaning mechanisms, and also have long-lasting filters to minimize downtime. Robotic welding will also produce a large amount of weld fume with the same requirements.
On the other hand, if you do mostly manual welding and use the weld stations only on an intermittent basis, the ideal option may be a small portable fume extractor. This equipment can be turned on and off depending on demand.
Identify where weld fumes are generated and what your facility lay-out allows in terms of equipment location. It’s always preferable to remove fumes close to the point of generation. Source fume extraction means each weld station has its own collection hood, extraction arm, or a workbench to capture weld fumes specifically generated by that operation.
There may be layout considerations that limit the use of source collection, however. If there are overhead cranes, limited floor space, or no room for ductwork, these factors may dictate an ambient fume extraction method. In this method, no capture equipment is used at the weld site; rather, an ambient collector draws in fumes from the entire area.
Another factor to consider is whether you frequently rearrange your layout. Ambient fume extraction may not need to be reconfigured when you change your layout, while source extraction needs to move with the welding equipment.
If you select source collection, you then need to decide where to locate the equipment in relation to the weld stations. Facilities with spread out workstations find it convenient to use a point-of-use layout where one collector is connected to one welding operation or station. Since each welding point has its own extractor, it’s smart to select an extractor with a small footprint that can be placed directly adjacent or close to each workstation.
In other shops, it might work best to use a centralized strategy. In these installations, one collector serves multiple workstations, and the stations are connected to the extractor through a network of ducts. In these layouts, the centralized collector is typically located some distance away from the welding points and maybe a good option if floor space is limited near the welding.
Once you’ve determined your weld process, facility limitations, and extraction goals, you’re ready to select the extractor itself. This equipment draws in contaminated air, filters out particulates, and exhausts filtered air outdoors or possibly back indoors. Particles that settle out in the extractor are collected in waste containers.
There are two types of extractors – cartridge or filter-pack – named for the filter style inside the equipment. The filter is the component that captures the fume particulates. Both filter technologies work well, so which one you choose may be driven by the location of equipment and whether a point-of-use or a centralized collector arrangement is selected.
Cartridge systems come in a wide variety of designs and sizes. Their pleated filters are easy to change and provide maximum particle-holding capacity in a compact footprint. In this category are the Donaldson family of Downflo® collectors.
Filter-pack systems work well as point-of-use extractors, for example, next to robotic weld cells, or integrated to work with the welding equipment by the manufacturer. The Donaldson Torit® PowerCore® TG is in this category.
Most Donaldson fume collectors come with a self-cleaning function where compressed air pulses the filters clean during operation, extending the life of the filter. This function requires a compressed air source.
When it comes to filters, it’s best to use one designed for sub-micron weld fumes, such as Donaldson’s Ultra-Web® fine fiber filters. The media traps dust on the surface, creating a dust cake that pulses off easily, which extends filter life.
Two other recommendations will help you select the ideal fume extraction system for your application: