HAZARDOUS AREAS & SAFETY FEATURE TAKING ON THE ENEMY OF PRODUCTIVITY
Dust and fumes not only present a potential danger to operator health, they can also impact productivity. BOFA International advises on effective ways of capturing and filtering airborne emissions, for both operator safety and plant efficiency
F
ume 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 impact productivity and add unnecessary cost. Exposure levels to potentially harmful
airborne emissions are tightly mandated through the COSHH (Control of Substances Hazard to Health) regulations and expressed as workplace exposure limits (WELs). These limits are presented in EH40 as time weighted averages for either 15 minutes or 8 hours and in both ppm (parts per million) or mg/m3 (milligrams per m3
). Typically, airborne contaminants are
produced through activities such as laser and ink jet coding onto food and pharmaceuticals packaging, soldering, laser cutting and engraving, spraying, and hand and mechanised grinding. Potential health problems are often
associated with plastic processing and solvents, which can give off Volatile Organic Compounds, the associated WELs of which must be complied with under COSHH. 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 extremely toxic. “Employers are under a legal obligation
to assess the risk to health created by work involving hazardous substances, taking account of any relevant WELs,” said Joshua Evans, applications engineer at BOFA International.
The risk and hazard of exposure to such
substances can be managed through the following hierarchy: firstly, doing away with the process; changing the process; installing local exhaust ventilation (LEV) and; lastly, using personal protection equipment or respiratory protective equipment. The key decision for operations and
health and safety managers is to evaluate the most effective means of capturing airborne emissions and filtering them appropriately, both for operator safety and for efficiency. Typically, these options would include
captor hoods, which depend upon 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 production such as laser coding or PCB manufacture. There are also challenges that go
beyond capture. For example, extraction systems linked to thermal processes need to take account of potential fire risks. This is particularly important where a combustible dust can be drawn into the filtration system. Managers should look for a system
using fire-resistant materials for casings and filters along with multiple thermal cut-out protection. The pre-filter stage is also critical in combatting any fire risk, as the larger particles removed by this stage remain hotter for longer, so ensuring that
The AD Oracle includes BOFA’s Intelligent Operating (iQ) system which offers
independent filter status monitoring to improve extraction efficiency
these are captured within a steel drop-out chamber is key. For many of these processes, hygiene is key in preventing the build-up of combustible material at any stage of the process. For example, BOFA has just released Spark Arrestor and FireBOX technology to mitigate the risk of burning particulate entering the fume and dust extraction unit. Filtration technology is also advancing,
with the availability of BOFA’s patented DeepPleat Duo pre-filtration, which uses reverse airflow operation to reduce the velocity of contaminant as it enters the filter chamber. This means that larger particulates fall into the steel drop-out chamber, with smaller particles being drawn into the DeepPleat filtration media. The smallest particles pass into the main High Efficiency Particulate Air (HEPA) filter, while vapours and gases are removed via a layer of activated carbon. The other key element for productivity
BOFA has just released Spark Arrestor (left) and FireBOX technology (right) to mitigate the risk of burning particulate entering the fume and dust extraction unit
is extraction system control. BOFA’s Intelligent Operating (iQ) System, has been enhanced with features such as independent filter status monitoring, to improve extraction efficiency. This ensures that filters are changed to schedule, reducing the risk of downtime and lowering the overall cost of ownership. The technology includes local and remote diagnostics capability. The control provided by the iQ system also means more consistent extraction, reducing the risk of build-up of potentially flammable particulate. BOFA’s next generation of fume extraction technology – iQ2 – launched in 2019 includes features designed to help promote the use of greater automation, envisaged by Industry 4.0.
BOFA International
www.bofainternational.com
PROCESS & CONTROL | OCTOBER 2019 21
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