Please enjoy this article written by Scott Snell, Technical Sales Manager, with Purex. The article is a great recap of fume extraction and how it relates to laser systems.
WHAT IS FUME EXTRACTION?
Fume Extraction is an engineered control method to capture fumes from processes that generate them… When we talk about Fume Extraction in the realm of Laser operations, we are typically talking about capturing the contaminants contained in the plume generated by the laser cutting, etching, ablating, annealing, etc.
WHY IS FUME EXTRACTION USED IN LASER CUTTING?
Specifically in laser use; Laser Generated Airborne Contaminants or LGAC’s can contain things more problematic than most consider. For example, when cutting Stainless Steel you don’t just get stainless steel powder, you get Chromium and Nickel. When cutting Tool Steel you don’t just get tool steel powder you get Vanadium and probably Cobalt. This gets even stranger in polymers, with PVC you don’t just get PVC dust. You get HCL, Benzene, Methanal, PAHs, and Phosgene.
It is important that both your employees and sometimes equipment be free of these hazards.
Another thing to consider is beam delivery to the target substrate. This beam needs to be consistent for consistent results and if there is a plume from the lasered substrate, the beam can become scattered and the product being marked/cut/etc. can suffer due to beam divergence.
Additionally, there are some basic tenants to why people use fume extraction for processes that generate hazardous fumes in general:
SAFETY
Fumes can contain harmful particles, vapors, and gasses causing short- and long-term health concerns to those who come in contact. Purex Fume Extractors use multi-stage filtration to remove harmful fumes and return clean air back to the working environment.
COST
Exhaust installation and modification to roofs can be expensive. Additionally, maintaining air balance and loss of heating energy through outside ducting results in added utility expenses. Fumes not properly handled lead to employee discomfort, increased health care costs, and lost time at work. Local fume extraction does not require modification to the structure or permitting and improves the air employees are exposed to.
ENVIRONMENT
Fumes dissipated by fans or exhausted outside are still harmful and can re-enter the facility through doors and windows. Filtration is the only way to remove harmful fumes and keep them from the environment. Vapors exhausted are transferred to neighboring businesses, schools, homes, etc. Local exhaust ventilation through a fume extractor filters the particles, vapors and gasses then returns clean air inside the facility.
CONSISTENCY
Purex Fume Extraction equipment maintains a steady volume of air flow. Outside winds and atmospheric pressure changes can impact the air flow from a facilities exhaust system. This can negatively impact certain processes and the rate at which fumes exit the facility.
LOCAL LEGISLATION
Many local laws prevent exhausting of fumes to the outside environment or require expensive and time prohibitive permitting.
FLEXIBILITY
Processes exhausting through hard piping to the outdoors are difficult to relocate. Purex Fume Extraction units are easy to move and make the process more portable.
WHAT ARE THE DIFFERENT FILTERS?
Most acceptable Fume Extraction Devices for laser fumes have the ability to offer at least 3 stage filtration: Pre-Filter(s), a HEPA Filter and a Carbon or Chemical Filter.
PREFILTERS
Capture gross particulate and protect the Carbon/Chemical and HEPA filters from being blocked. In the case of the 5000i HD, there are 2 levels of prefilter. The first is a G3 which has about an 88% arrest level of large particles and offers high dust loading. The Second pre-filter is more for protection of the HEPA and Chemical filters. This unit has two F8 filter cartridges that can capture particles from 1-3 microns with a rate of efficiency between 90 and 95%.
CHEMICAL
We refer to it as Chemical because it is not just activated carbon. This filter has carbon that has been bleached and then treated with chemicals. This aids the carbon in adsorption of gasses and Voc’s.
HEPA
The HEPA filter removes the remaining particulates down to .3 Microns with a rate of efficiency 99.997%.
WHAT IS BEING FILTERED IN THOSE FILTERS?
In laser processes particulate of various sizes generated down to the .3 micron range is generated as well as a broad range of gasses and VOC’s.
WHY A PUREX FUME EXTRACTOR?
For the same reasons people buy a Kern Laser… tough, reliable, cost effective, industry leading solutions that actually work.
Purex units are built on a fully welded Stainless Steel Chassis. Their filter locking methods are simple to use and filters are easy to change when necessary. Good filtration starts with a Good Filter, Purex Filters are some of the toughest in the industry. Besides filtration method, and ease of use, Purex units monitor return air quality for VOC’c and particulate to be sure the filtration process is being achieved. They also monitor air flow in real time to ensure consistency. Additionally, regarding my previous statement on how “beam delivery to the target substrate need to be consistent,” Purex units employ flow control. This means that the blower ramps up in speed as the unit detects that filters are becoming blocked allowing for similar air flow throughout the life of the filters. This helps reduce bad cuts and marks, rejected product and wasted materials.
HOW DOES PUREX STAND OUT?
For more than three decades, Purex International Ltd has manufactured fume extraction systems with focus on improving product quality, reducing process costs, and bringing the future of fume extraction solutions to our customers!
So, what makes Purex stand out as world leaders in the fume extraction industry?
INDUSTRY EXPERIENCE
We provide high quality technical support to assist with extract enclosure / nozzle design, or to help solve practical extraction difficulties.
EASE OF MAINTENANCE
All components can be removed in minutes without the need for special tools, again, resulting in reduced downtime.
LONG FILTER LIFE
Due to its large surface area and graduated fiber densities.
REDUCED DOWN TIME
Filters can be changed in minutes.
FULLY DISPLAYED
Comprehensive instrumentation for filter condition and sensor status. Comprehensive gas and particulate monitoring system.
QUIET
Brush-less motors used in our systems result in improved operator comfort.
AUTOMATIC FLOW CONTROL
Easy set up of extraction volume for any process and automatic adjustment as the filters become blocked.
AVAILABLE INTERFACING
Two way interfacing enable our units to be switched on and off remotely and warning signals to be received by integrated control systems.
ENGINEERED
Welded Stainless Steel Chassis.
