Weld Fume Management Guide: Finding the Right Source Capture Ventilation System
March 28, 2016
How to Choose a Source Capture Ventilation System for Controlling Weld Fumes
Source capture weld fume extraction is the most effective method of keeping smoke out of the welder's breathing zone – an incredibly important task given the dangers of weld fumes. Ventilation at the source is also the preferred way to maintain target levels of whole-plant indoor air quality (IAQ). With those facts in mind, some facilities decide to rely solely on source capture to remove fumes while others implement a complementary assortment of ambient and source capture technologies.
Whichever route is taken, choosing the ideal source capture system for each facility can seem like a daunting task. This weld fume management guide, Finding the Right Manual Welding Source Capture Ventilation System, will illuminate a number of considerations to be mindful of as facilities decide on the appropriate clean air technology.
6 Source Capture Considerations to Keep in Mind When Deciding
To increase efficiency throughout the source capture system search, buying, installation and use processes, the following six considerations should be taken into account. A few are very straight-forward while others, like necessary airflow, may require the assistance of professionals.
Available Space and Facility Layout
In manufacturing facilities, space is at a premium – in all directions. Less available surface space sometimes translates to less productivity on the floor which affects the bottom line in both the short- and long-term. Some facilities have overhead cranes or similar aerial components to plan around which create literal obstacles to source capture system design.
Luckily, source capture ventilation systems are available in multiple configurations from centralized ducted systems to stand-alone workspace units. From there, systems can be further segmented. Central ducted systems can incorporate either repositionable fume arms or immovable vent hoods. Standalone systems can envelope the workstation or be integrated directly into the table itself with back or downdraft technology. Where space is at the ultimate premium, the central collection units of ducted systems can be placed outside the facility to maximize floor space.
Movability can mean multiple things when it comes to weld fume extraction systems, but the common thread is convenience. Movability may refer to portability of the extraction units itself or whether or not the capture mechanisms can be repositioned.
For light-duty welding operations or processes such as cutting or finishing, portable weld fume source capture systems provide an unmatched level convenience since the units are built to move with the welder. From weld-tip fume extraction to multi-fume-arm units, portable units weld fume extraction solutions are more versatile and durable today than ever.
A more permanent but certainly moveable weld fume solution is a ducted one which incorporates fume arms. Fume arms, sometimes called elephant trunks due to their resemblance, feature a cone-shaped hood attached to a long, flexible hose. The fume arms can be repositioned as the welder moves about the weldment to achieve proper source capture.
The sort of welding processes taking place, for instance MIG, TIG, Stick or Spot Welding, may affect the outcome of your search for a source capture solution. Each welding process creates a different amount of fume, sparks and particulate that must be addressed.
Along the same lines, it is important to note whether your welders will be human, automated or a combination of the two due to the drastic differences in productivity that automation can achieve. It should be easy to understand that automated processes are more productive and therefore create a larger amount of weld fume. It is important to have a system that can keep up. At the same time, robotic units operate at a high rate of speed, making repositioning a fume arm inefficient, and for this reason, vent hoods are most often integrated into automated welding cells.
Proper Weld Fume Filtration
Capturing weld fume is not the end of the road for source capture units. Toxic smoke must be filtered before clean air can be reintroduced to the plant environment. There are a number of considerations to take into account while investigating this often-overlooked piece of the weld fume capture equation.
The textbook approach to the amount of filters to incorporate is a two-to-one air-to-cloth ratio. This means you need at least 1,250 square feet of filter media to extra fume out of a 2,500 square foot space. Keep in mind that typical filter cartridges have roughly 200 feet of cloth inside. Since the cost of filters can quickly add up, it is recommended to “over-rate” the ratio by 25%. This increase of filter media upfront can extend filter life up to twice as long in some cases.
Once the air-to-cloth ratio is determined, it is important to be mindful of two additional concerns for capturing weld fume: spark and mist. Sparks and filters don't mix, so it is important to invest in a system with spark arrestance technology to ensure they never reach the flammable paper cartridges. In terms of mist, the key is to understand the make-up of weld fume in an environment. If it contains oil mist, for instance, this should be accounted for as standard paper filters will quickly become overburdened leading to high consumable costs.
Finally, the orientation of filter cartridges can have a major impact on the overall effectiveness of the unit. Vertical filters are preferred as they allow for collected dust to be shed directly down into a collection tray after pulse-cleaning. In horizontal layouts, dust and debris tend to be shed only from the bottom two thirds of the filter leaving the top third less effective. The result of this leftover dust can be as much as 40% less available filter area and drastically reduced filter life.
Necessary Airflow to Move the Weld Fume and Smoke Created
Airflow is measured in Cubic Feet per Minute (CFM) and refers to how much air a system can move in a minute. A variety of factors should be considered when choosing an appropriate CFM goal including the amount of weld fume generated and outside forces present in the facility.
With the help of an Airflow Calculator, it is possible to predict the effect a given CFM will have on a shop environment. This is an important step since post-installation is too late to be making wholesale system adjustments – especially if a tight budget or timeline is being adhered to, as they often are.
Within airflow calculations and modeling, outside forces should be considered as they can drastically affect the ability of a source capture system to perform at peak level. For instance, a moderate breeze can move air at about 700 feet per minute. This amount of force could easily overpower and fume extraction system designed to capture weld fume moving 80-150 feet per minute in a closed environment.
Long-Term Cost of Maintenance
The best way to avoid maintenance costs is to buy a well-made system upfront. Sturdy systems will feature sealed cabinets made of durable materials and protect system components from any potential hazards. World-class industrial ventilation providers will install units themselves, be willing and able to handle any comprehensive maintenance, and provide a lifetime warranty for the duration of the contract on all parts and labor as proof that they stand by their design. After all, a very important and costly investment was made, and it is reasonable to expect it to last.
Controlling Weld Fumes with RoboVent
RoboVent are the leaders in clean air technology with decades of experience providing a variety of industrial ventilation solutions. More important, RoboVent is more than a supplier – they are a team of engineering professionals committed to delivering systems and products that improve the environment, process systems, and the health and safety of your workers.
RoboVent assumes total project responsibility for the systems it delivers meaning there is a single source of responsibility for you to rely on. While quality and construction and continued technological innovative are vital to the service RoboVent provides, it is the personalized customer care that sets our solutions apart.
Contact RoboVent today to learn more about our innovative systems, processes and approach.