FAQ CATEGORY: Fume Guns

Fume guns and fume arms require different dust collectors. Following is a brief breakdown of what each device needs on the suction end.

• Fume guns - A fume gun places the extraction point right at the point of fume creation, ensuring efficient capture. The nozzle is small and handles a high vacuum pressure—around 80 inches of pressure. While the pressure is high, the airflow is modest—around 60 CFM (cubic feet per minute), versus a fume arm’s 600-1,200 CFM (based on arm diameter). Fume guns work well with hi-vac (high-vacuum) equpiment like RoboVent’s Hi-Vac unit or the ProCube unit.
• Fume arms - A fume arm is much less particular than a fume gun and can be attached to a wide variety of dust collection equipment. Fume arms work with a lower pressure and higher airflow than fume guns. They might be found on portable dust collectors, such as RoboVent’s PowerBoom collector. They can also be attached either to standalone dust collectors or plugged into a ducted, centralized system.

Fume guns are excellent source capture solutions for weld fumes. When used properly, they can capture up to up to 95% of weld fumes. Here are two major factors that affect the capture rate of a fume gun:

• Holding position - It is important to hold a fume gun at the correct angle. This allows the capture nozzle to be in the proper position as the fumes are being created. The location matters as well—a fume gun does not work very well upside-down, since weld fumes rise. As most welders know, a little training goes a long way and can significantly improve the capture efficiency of the fume gun.
• Extraction rate - Fume guns capture weld fumes using high pressure and low CFM (cubic feet per minute). The suction hose on the gun is attached to a high-vacuum (hi-vac) collector, which provides strong suction through the small hose. The CFM of a fume gun is much lower than that of, say, a fume arm—60 CFM versus 600-1,200 CFM, respectively. The suction rate must be properly balanced so that it does not interfere with shielding gasses, leading to poor-quality welds.

It should be remembered, however, that fume guns are not appropriate for all applications. For example, in confined environments, residual weld fumes can build up and expose a worker to excess fumes if no other protections or ventilation units are in place. Weld seams often emit a certain amount of smoke after welding, and the fume gun won’t capture all of it. This is especially the case when welding materials that result in excessive smoking. In these situations, an ambient system may be needed to collect leftover fumes that escape into a facility’s air.

Fume guns are a powerful solution for source capture of weld fumes, but they are not best for all situations. For example, fume guns work well with MIG welding, but not for other types of welding. Resistance welding, for example, creates welds that smoke for a long period of time. A welder using a fume gun in that situation would have moved on to a different area, leaving those fumes uncollected. In those situations, a fume hood or an ambient air filtration system would be needed to capture the fumes produced.

Other situations where fume guns are not appropriate include times when a welder must work in an unusual position. For example, welding upside down significantly reduces capture efficiency for fume guns. A fume gun must be positioned correctly to grab weld fumes before they get away. Another case when fume guns don’t work well is when a surface has an oily coating. When these pieces are welded, the hot seam continues to produce smoke long after the welder has moved on.

Fume guns are an excellent option for any application using manual MIG welding. The fume gun is the ultimate source capture solution for weld fumes. Adding an extraction system to a lightweight MIG welding torch produces a tool that is as flexible as it is powerful. This flexibility makes fume guns ideal for applications where other fume capture methods fall short—in particular, when welding on large pieces or in tight, confined spaces.

When welders work on large pieces, such as truck trailers, they rarely use portable source capture solutions properly. Constantly repositioning a fume arm or dragging a large piece across a backdraft table is often inconvenient or even impossible. The same goes for working inside aircraft fuselages, tanks or other small spaces. These applications requiring high welder mobility are where a fume gun shines. A fume gun allows a welder in these situations to collect fumes while continuously welding.

Fume guns are also the most cost-effective and energy-efficient method of capturing weld fumes. Fume guns capture fumes closer to the source than any other capture method, which means they require less airflow (measured in cubic feet per minute) than other methods. This saves significant amounts of energy and money.

Before making any final decisions about wearing respirators, plant managers should do air quality tests to study the effectiveness of various solutions. The best fume guns capture up to 95% of weld fumes in many scenarios, which is enough to avoid the need for respirators. However, factors such as welding position, the material type and presence of certain coatings or lubricants may impact capture efficiency.

Implementing fume guns in your facility would be a major step in protecting workers and making the use of personal respirators less necessary. Installing an air filtration solution—source capture, ambient capture or a combination of the two—is the best method of bringing air quality within regulations, while also protecting workers and saving money through energy efficiency.