Fume and dust are the enemy of process-based operations. Poor workplace practices, particularly where hazardous materials are being worked, not only present a health risk to employees, they can also significantly impact productivity through downtime and create unnecessary cost for businesses.
In the UK, exposure levels to potentially harmful airborne contaminants are tightly mandated through the COSHH (Control of Substances Hazardous to Health) regulations and expressed as workplace exposure limits (WELs). These limits are presented in the Health & Safety Executive’s EH40 guidance as time weighted averages for either 15 minutes or 8 hours, in both ppm (parts per million) or mg/m3 (milligrams per m3).
“Employers are under a legal obligation to assess the risk to health created by work involving hazardous substances, taking account of any relevant WELs,” says Joshua Evans, an applications engineer at BOFA International, a global leader in portable fume extraction.
“Potentially harmful airborne contaminants can result from numerous industrial processes, including laser and ink jet coding onto food and pharmaceuticals packaging, soldering, welding, laser cutting and engraving, spraying, and hand and mechanised grinding.
“Health risks are also associated with plastic processing and solvents, which can give off Volatile Organic Compounds. PVC is worth a special mention in this context since it releases hydrogen chloride and small amounts of phosgene when lasered or thermally processed, both of which are very harmful.”
The key decision for health and safety managers is to evaluate the most effective means of capturing these potentially harmful emissions and filtering them appropriately, both to ensure operator safety and to contribute to a more efficient production environment.
Typically, these options include captor hoods, which use a capture velocity across the source of the emissions; receptor hoods, which use the movement of particles / vapour towards the device to capture them; partial enclosures, which extract contaminants typically for hand grinding and finishing; and full enclosures matched to the needs of automated processes such as laser coding or PCB manufacture.
“There are also challenges that go beyond capture,” says Joshua Evans. “For example, extraction systems linked to thermal processes need to mitigate any potential fire risks. This is particularly important where a combustible dust has the potential to be drawn into the filtration system.”
Under these circumstances, managers should specify a system benefiting from fire-resistant materials for casings and filters and thermal cut-out protection. In the case of BOFA, the company has developed sophisticated Spark Arrestor and FireBOX technology to mitigate the risk of burning particulate entering the fume and dust extraction system.
Filtration technology is also advancing, for example through BOFA’s patented DeepPleat Duo pre-filtration, which uses reverse airflow to reduce the velocity of contaminant as it enters the filter chamber. This means that larger particulates fall into the steel drop-out chamber, while smaller particles are drawn into the filtration media. The very smallest particulate passes into the main High Efficiency Particulate Air (HEPA) filter, while vapours and gases are removed via a layer of activated carbon. Once this process is completed, clean air is returned into the workplace.
The other key determinant for optimal productivity is extraction system control. BOFA’s Intelligent Operating (iQ) system provides independent filter status monitoring to determine filter replacement in the most timely manner, thereby reducing the risk of downtime.
Concludes Joshua Evans: “In short, better information means better extraction performance and the avoidance of unnecessary downtime - and a safe breathing environment for operatives.”
