Frequently Asked Questions

Q. What do I need to know about a fume and smoke control system, and how can I make sure it will work?

A. Many fabricators today have been disappointed with fume extraction systems for their processes, as improper sizing and misapplication of equipment is the #1 cause for a system’s failure. In fact, it has been proven that over 50% of the fume extraction systems installed in the metal fabrication industry do not work as well as intended, and often from the time of installation.

Some factors to consider:

• What metal fabrication process (or processes) are taking place (Welding, grinding, plasma cutting, etc.)
• Further information on Manual Welding, Robotic Welding, Ambient Ventilation and Weld Schools
• How many workers are being exposed to smoke and fumes
• Size of facilities
• An estimate of how much smoke/fume is being produced
• Budgetary considerations

Q. Can I just blow dirty air outside?

A. There is often no issue blowing dirty air outside from an environmental standpoint. Although government regulations on this will tighten up over time, most companies are allowed to blow a certain amount of dirty air outside.

The issue with exhausting the air outdoors is the negative pressure produced on the facility (and other issues, see “Air Quality” section). This is usually OK in the summer, with open doors allowing air back into the facility. During the winter, exhaust fans don’t work well with the doors closed, as no air is allowed back in to replace the air that is sent outside, creating negative pressure.

Q. How often would I have to change filters in a filtration system?

A. This depends on your fabrication process, but a filtration system properly sized for your process and facility should get between 6-12 months filter life in normal conditions. See Products for further details.

Q. What kind of ventilation system is best for my operation? I am hearing the terms “filtration”, “exhaust” and “source capture”, what do they mean?

A. With employee health and plant safety and cleanliness becoming more of a priority for the metal fabrication industry, the ventilation industry has developed a wide range of methods and products.

Here are some examples:

 

 

 

 

 

 

 

 

 

 

 

 

General Ventilation – Exhaust
Large exhaust fans draw dirty air from the plant and exhaust it directly into the environment, typically through the roof or walls. This is a traditional method and often results in negative air pressure, and also makes it very difficult to climate-control your facility.

 

 

General Ventilation – Filtration
Large blowers and air cleaning equipment draw contaminated air from the plant (typically at the ceiling level), filter it and return it to the plant. This is a proven solution in facilities fabricating large parts with overhead cranes. It reduces the haze in the air, resulting in a cleaner facility, with no negative pressure or heat loss.

 

 

Source Capture – Exhaust
Air in the immediate area of the process is captured in a hood, sent through ductwork, and exhausted directly into the environment. The intent of this system is to exhaust as little of the plant air as possible, while still catching the fumes. This is a lower cost alternative to filtration but tends to result in large ducting systems and negative pressure problems.

 

 

Source Capture – Filtration
Air in the immediate area of the welding activity is captured in a hood system, then filtered and returned to the plant. This is the best solution whenever possible. It allows for a more flexible system and removes the smoke directly from the operator’s breathing zone.

 

 

Q. What is considered “good” air quality?

A. Generally speaking, if the air is visibly clear and you are comfortable working in the facility the way it is, that would be considered “good” air quality. The best way to ensure that air quality meets or exceeds the OSHA Permissible Exposure Limit (or PEL) and/or other regulations is to have an industrial hygienist do an evaluation on your workers and facility as a whole.