By design, laser cutters create fumes and micro-particles from the material they are cutting or engraving. For health and safety reasons, these fume and particles are required to the exhausted away from the workspace and people to a safe location, such as open air outdoors. This is a common set-up, even without lasers. For example, the same system is used to exhaust heat fumes from clothes driers in people’s homes. This system requires an exhaust fan (to pull the fumes), ducting (to transport the fumes) and an exhaust port (to release the fumes outside).
Fume extractors do the same thing, however, instead of releasing the fumes outdoors, they pull the fumes through a complex filter system that catches the particles and purifies the fumes to safe levels of contact. It works remarkably well because of the three different types of filters. Different fume extractors may have different configurations of this filter types, but they all work the same way.
The pre-filter is usually made of pleated cotton and traps dust and other larger particles. This helps trap much of the small debris that can cause choking and irritation to the lungs, eyes and throat. As the particles are trapped, they can be clearly seen collecting in the filter. Note that even though this filter is typically cotton, you should never wash these filters like clothing. They can be cleaned with a hand-held vacuum cleaner to extend the life of the cotton filter, but once saturation reaches 70% or so it will need replacing.
HEPA stands for High-Efficiency Particle Arresting and that is exactly what HEPA filters do. They typically use a polypropylene mesh (fiberglass) to capture very small particles. While HEPA filters are designed to capture very small particles, they do not filter out gases or odors. Regulated but the US Department of Energy, HEPA filters remove up to 99.97% of airborne particles. This is crucial for allergy and asthma sufferers. Like the other filters, they are consumable items and will eventually need to be replaced.
The main filter system are the activated carbon filters. These are usually a series of carbon filters whose purpose is to remove small particles and material fumes such as the gas produced when cutting acrylic. These work much like carbon-based water purifiers. It is through the carbon filters that foul odors and fumes are eliminated. These too can be periodically cleaned for extended use, however, once the laser operator starts to notice odors in the air again, it is time to replace them.