Recent advancements in source capture technology are making it an even better defense against weld fume, resulting in a safer and more productive welding environment. New source capture technology is available that creates a much larger fume extraction area than what was previously offered in the marketplace — up to 3 feet wide and 5 feet away (compared to the average of 12 to 18 inches away). This larger capture zone minimizes operator interaction with the fume extraction arm, which helps increase productivity and improve weld quality by reducing the need to pause repeatedly for adjustments.
Why and when to consider source capture: The push to establish and maintain safer work environments is, in part, the result of increasingly stringent regulations and recommendations for controlling weld fume. The Occupational Safety and Health Administration (OSHA) and the American Conference of Governmental Industrial Hygienists (ACGIH) both have limits for elements such as manganese and other weld fume particulates.
If a company finds itself exceeding OSHA’s regulation for the permissible exposure limit (PEL) of weld fume — currently set at 5 milligrams per cubic meter for manganese, for example — or the threshold limit value (TLV) set forth by ACGIH — 0.02 milligrams per cubic meter for the same element — a practical fume management solution is a good way to address the problem. There are three key ways to implement a fume management solution.
1. Process modification or substitution is a good first step in any effort to reduce weld fume. Companies can move toward a lower fume generation process when possible, modify weld settings and/or switch to low manganese wires to reduce the amount of fume generated. Work practice changes, such as teaching employees proper weld positioning to minimize exposure to the weld fume path, is another important step for protection.
2. If the above efforts are not possible — or if a company has implemented them but needs to consider additional efforts to further reduce weld fume exposure — implementing preferred engineering controls like source capture via an appropriate fume extraction system, is the next recommended step. Advanced source capture systems are a particularly effective option.
3. For a final solution, the addition of personal protective equipment (PPE), such as powered air purifying respirators (PAPRs), air supply helmets and/or half-mask respirators, can help eliminate exposure and also cool the welding operator’s face with airflow.
As a point of focus, this article will discuss the second step in fume management solutions, particularly the workings and benefits of advance source capture technologies.
How advanced source capture technology works
Advanced source capture technology works by way of a negative pressure zone. The extraction arm suctions in air at a standard fume capture rate of around 900 cfm, while simultaneously, clean filtered air moves out of the arm (at a point just above the hood portion of the extraction arm) at approximately a 90-degree angle. Additionally, some of the air that discharges out of the extraction arm “short circuits” and circles back around, effectively allowing a portion of the filtered air to capture more fume particulates before being suctioned up again.
Combined, these actions create a very defined area of source capture, which funnels the weld fume particulates toward the center of the arm to maximize the extraction process.
This advanced technology is most effective when strong air currents or turbulence, such as fans or open doors, are kept at a minimum. Welding operators can manage such air currents by using welding screens, curtains or other similar partitions to block the stronger air movements. Make sure to maintain clearance of at least 5 feet on all sides of the fume extraction system when setting up a partition.
The fume extraction capabilities of these advanced systems also are best realized when the extraction arm is placed at 30 to 45 degrees off horizontal, either in front or at the side of the weld area so that backfill air can flow freely and fume is pulled away from the breathing zone.
Productivity and safety benefits
While exceptionally efficient at protecting the welding operator’s immediate breathing area, traditional source capture methods sometimes have arms that are difficult to position without significant welding operator interaction. This interaction can especially be an issue for applications with large weldments (such as those found in heavy equipment manufacturing or heavy fabrication) or areas within the weld cell that include obstructions. Applications with frequent, intermittent welds can also pose a problem.
The need to pause repeatedly for fume extraction arm adjustments can lead to downtime and, potentially, weld defects due to the repeated stops and starts in the weld. Some operators may even choose to forgo arm adjustments in an effort to meet productivity demands, which can lead to more fume in the weld cell.
The wider, deeper and more defined source capture zone created with the advanced technology results in less downtime for the welding operator to pause to reposition the arm; reduces the chance of obstructing the welding operator’s vision since fume is captured at a greater distance; and offers consistent extraction arm position for safety and quality.
Welding operators can adjust the zone capture area to be more narrow and direct. This adjustment prevents the discharge airflow from deflecting off parts or swirling around, and it increases suction. The feature also helps ensure that airflow won’t interfere with the shielding gas coverage and lead to weld quality issues.
The advanced source capture systems also feature automatic cleaning mechanisms. Every time the machine is shut down, it goes through a reverse pulse cleaning cycle, which cleans the filter from the inside out. The process removes weld fume particulates from the filter, depositing them into a drawer for later disposal. This cleaning cycle helps extend the filter life, maintain higher airflows, reduce the time spent on maintenance and minimize downtime for changeover.
Other source capture options
Companies have different weld fume management needs and will want to consider the various methods to reduce weld fume exposure. In addition to the advanced source capture technology discussed previously, there are other options for creating a safe work environment. These fume extraction systems come in multiple shapes and sizes, with each type having its own advantages, considerations and best applications. Below are some details of other source capture offerings.
Portable models: These models work well for applications in small spaces or hard-to-reach areas. They are also good for maintenance and repair operations or contract jobs where welding doesn’t occur on a regular basis. Portable fume extraction systems can couple with fume extraction guns that capture weld fume directly at the source via a fume chamber over the gun nozzle or by way of a flexible nozzle attachment. The attachments offer high levels of suction and employ small diameter hose or ducting with lower overall air volume, meaning the source capture distance is much closer to the weld, usually about 6 inches away.
Mobile floor models: These feature an adjustable extraction arm that the welding operator can move toward the weld pool to remove the fume from up to 18 inches away. These models work well in maintenance and repair operations, fabrication shops and manufacturing facilities where mobility is important or overhead obstructions make them necessary.
Stationary fume extraction systems: These are a good choice for companies with dedicated welding cells. They can be mounted on a column or wall and feature an extraction arm that is adjustable, so it is simple for the operator to shorten the distance to the arc and efficiently remove the weld fume from the area. Wall-mounted versions can be expanded to two arms, taking the footprint off the shop floor and allowing for more room in the weld cell to expand welding operations.
Centralized fume extraction systems: These systems offer fume capture capabilities ranging from 2,000 to 60,000 cubic feet per minute (cfm). Companies with multiple arcs or with robotic welding cells may want to consider this option. They can be customized with mechanical extraction arms, backdraft hoods and tables and/or overhead collection hoods that cover the welding area.
Making the source capture decision
Employing source capture in the welding operation can help companies maintain compliance with regulations, avoid potential fines and create a safe and comfortable work environment for employees. Once a company decides to implement source capture, selecting the most appropriate type of system for a given welding operation can be more difficult. There are considerations to make in terms of cost, space requirements and the actual welding application.
The advanced source capture technology discussed in this article greatly increases the fume extraction area and offers reduced operator interaction with the extraction arm, offering safety and quality benefits. It’s a good idea to consult with a trusted welding distributor or industrial hygienist to determine whether this technology or another type of fume extraction system is the best choice for the application at hand.