What’s the best way to keep weld fumes out of the welder’s face – and lungs? There are a lot of options when it comes to weld fume extraction, but many welders overlook fume extraction
guns. Today’s sleek, lightweight models provide excellent fume extraction without impacting weld seam quality or welder comfort. And they may do a better job of keeping weld fumes out of the breathing zone than other alternatives.
Weld fumes present a serious risk for welders when they are inhaled. To protect welder safety and maintain compliance with OSHA standards, some form of fume extraction typically is required for manual welding processes.
While most robotic welding applications can be kept under a hood for fume extraction, manual welders need a solution that keeps weld fumes out of the breathing zone. Several good options for manual weld fume extraction are available.
Fume arms are long movable arms that are positioned over the weld seam to collect fumes as they are created. For larger pieces, fume arms must be continually repositioned to ensure they are in the proper position over the seam. For this reason, they are typically not the right solution for larger weldments and are best utilized for smaller parts that don’t require fume arm repositioning.
Backdraft and sidedraft tables combine a welding bench with fume extraction. The intake plenum pulls weld fumes up and away from the welder’s face. Backdraft is an effective and economical solution for smaller benchtop-sized parts. These are often confused with downdraft tables, which are not very effective for welding but can work very well for grinding applications.
Fume extraction guns put weld fume collection right inside the welding torch itself. As welders create the bead, the fume gun extracts the weld fume as it is created. These guns can be a welder’s best friend by capturing the vast majority of the harmful particulates, keeping the welder safe and improving visibility. If the fume guns are not set up properly, they can cause porosity and weld integrity issues.
Fume extraction guns are used strictly for MIG welding. Generally speaking, any type of weld completed with a standard MIG gun can also be welded with most fume guns in the market. They offer some significant advantages for many welding scenarios.
- Unlike fume arms, fume guns do not require the welder to stop and reposition a separate piece of equipment while they are welding. This eliminates operator errors and is a more reliable method to keep the operator safe, as fume extraction is always right where it is meant to be.
- Fume guns can be used for larger weldments that do not fit on a standard welding bench or backdraft table and require significant mobility on the part of the welder.
- Higher end fume guns can extract 90 to 95 percent of weld fumes as welding takes place.
- Fume guns are the most energy-efficient form of fume extraction. Because they are collecting the weld fumes so close to the source, they require significantly lower airflow (cubic feet per minute [CFM]) for efficient extraction than fume arms, backdraft tables and hoods.
Fume guns can be used in place of a standard MIG torch for most applications. Fume gun allows welders to take extraction with them as they go. They are especially helpful for large weldments and applications that require the welder to reposition frequently: think large infrastructure pieces, ship hulls and silos. They may also be the only viable fume extraction option to keep fumes away from the welder’s face when working inside large tanks or ship hulls. There are a few caveats, however.
Welding in more awkward positions, such as overhead, may impact extraction efficiency for the fume gun. Also, some materials, such as coated or lubricated metals, continue smoking for a long time after the weld seam has been laid. The fume gun cannot pick up these fumes because the welder has already moved on from the area.
Choosing a different type of fume extraction system, or adding a secondary system, may be best in these cases.
Many welders discount fume guns because they think they will be too heavy and bulky or create a poor-quality bead. But modern extraction torches have largely eliminated these concerns. A high-quality fume gun should not have a negative impact on welder comfort, maneuverability or weld seam quality. There are a few things to keep in mind when selecting a fume gun.
- Ergonomics: Look for a fume gun that is lightweight and comfortable to hold. Many modern fume guns are about the same weight as their standard MIG torch equivalents and feature ergonomically designed handles and ball joints for added maneuverability.
- Shroud/nozzle design: The shroud/nozzle, or hood, is the piece of the extraction torch that actually collects the weld fumes. High-efficiency shrouds are larger and closer to the tip, allowing them to collect fumes more efficiently, especially when welding overhead or in other unusual positions. However, the tip is slightly bigger, which can impact visibility and the ability to get into tight spaces. Tapered shrouds are nearly the same size as a standard MIG torch, providing superior visibility and joint access.
- Neck design: The neck angle for the fume gun is usually anywhere from 30 to 60 degrees and may differ by manufacturer. The angle that works best is based on welder position.
- Air-cooled vs. water-cooled: Fume guns come in air-cooled and water-cooled models. Air-cooled torches are less expensive to buy and operate but typically are a bit heavier than water-cooled torches of the same amperage.
The fume gun is only half of the equation: It must be paired with a high-vacuum dust collection system. There are two basic options when it comes to connecting the fume gun to a dust
A portable high-vacuum dust collector works well for supporting only one or two welders. The fume gun is connected directly to the unit. These small units can be placed wherever they are needed. Some even come with wheels and handles so the welder can move them when working on very large weldments.
A centralized high-vacuum dust collection system may be best for supporting a large number of welding stations and if the welders do not require high mobility. A larger centralized dust collector can be hooked up to multiple stations. This sort of system will almost always be a high-vacuum cartridge dust collector. Enough extraction power (CFM) and static pressure (in water gauge) to support all stations that will be in use at the same time must be provided.
When designing a dust collection system for use with fume extraction guns, there are a few things to keep in mind.
- Spark arrestance: Welding generates a large number of sparks, which can cause a dangerous fire if they reach the filter cabinet of the dust collector. Small portable units should have spark arrestance built in. For centralized systems, an inline spark arrestance system can be installed at the inlet to the ductwork.
- Filter media: In most cases, the dust collector used for weld fumes will use filter cartridges. A filter media appropriate for the volume of weld fumes being collecting is important. Because thermal processes like welding create very tiny particles, filters with a rating of at least a MERV 11 or higher should be used.
- Filter cleaning system: This is especially important for high-volume welding operations. Weld fumes stick to the filter media and quickly clog the filters if the particulates are not pulsed off. A filter pulsing system or compressed air cleaning system pulses excess dust off the filters and into the collection bin for removal, extending filter life and reducing maintenance.
- Noise considerations: When using a portable high-vacuum unit or a centralized dust collector located in the workspace, excess noise can be a nuisance. The noise generated by the filtration units of different manufacturers can be significantly quieter for some more than others. An exhaust silencer can be used on many of the larger systems in the market, and that can help improve operator comfort.
In some cases, it may be desirable to set up a secondary ventilation or ambient air filtration system to collect weld fumes left behind by the fume gun. Even high-efficiency fumes guns used properly will not collect 100 percent of fumes. Fume guns also won’t do anything for residual smoke from hot lubricants or coatings burning off of the freshly welded parts while they cool. An ambient air filtration system will capture these residual fumes as well as general dust and contaminants from other processes.
Working with a trusted industrial ventilation partner can help end users find the design for their unique situation and engineer the proper solution. Air quality testing can always be done to determine whether air is within OSHA guidelines for weld fume safety. When used correctly, weld fume extraction guns are an excellent option to protect welders without slowing them down. Pairing the fume gun with the right high-vacuum dust collector for best results.