SAFETY & HAZARDOUS AREAS DEALING WITH CONTAMINANTS
Fume and dust are the enemy of process-based operations. Joshua Evans, applications engineer at BOFA, explains how to reduce safety risks and downtime
health risk to employees, they can also impact productivity through downtime and create unnecessary costs In the UK, exposure levels to potentially
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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 metres cubed). “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
oor workplace practices, particularly where hazardous materials are being worked, not only present a
Evans from BOFA International. “Potentially harmful airborne contaminants
can result from numerous industrial processes, including laser and ink jet coding onto food and pharmaceuticals packaging, soldering, and additive manufacturing. “Health risks are also associated with plastic
processing and solvents, which can give off Volatile Organic Compounds (VOCs). 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.” In the case of additive manufacturing,
studies confirm the presence of fumes and particulate in AM technologies, including in
FireBOX technology mitigates the risk of burning particulate
entering the fume and dust extraction system
fused filament fabrication (layered thermoplastics), in stereolithography (cured liquid resin) and in selective laser sintering (laser curing of a liquid resin or powdered material). In addition to risks associated with the
inhalation of VOCs, of particulate and certain gases, AM processes are also shown to emit nanoparticles, which have the ability to pass through membranes into the human body. Not only must these airborne
contaminants be captured, but uncontrolled particulate can also negatively impact product quality. For example, any prolonged release of sticky plastic droplets resulting from an AM process can lead to a build-up of material on the machine’s moving parts,
WHAT TO DO WHEN MACHINERY SAFETY AND EXPLOSIVE ATMOSPHERES MEET
Fatal explosions in UK factories are extremely rare thanks to the combination of stringent safety measures introduced over the years, designed to eliminate or control the risks from explosive atmospheres in the workplace, plus the availability of high-quality equipment to help meet those obligations. However, there’s no room for complacency – explosions can still happen even with apparently benign processes including food ingredients such as flour and
sugar. All technical equipment that is a potential ignition source can trigger an explosion under certain conditions, which is why Euchner has launched an upgraded range of ATEX approved safety switches and interlocks for use on equipment within potentially hazardous manufacturing environments. Conventional safety interlocks for monitoring or securing doors are generally not suitable within facilities where combustible materials are present, while the
common ATEX switch and locking solutions for these zones often fall short of the applicable machinery safety standards, including EN ISO 13849-1 and EN-ISO-14119. ATEX equipment manufactured by Euchner is suitable for use in Zone 2 (gas) and Zone 22 (dust)
environments with the recently developed Euchner CTP switch filling the gap between explosion protection and general machinery risk-reduction, such as preventing personnel access to rotating equipment. The ignitability of an explosive atmosphere depends on the material of course. Gases and vapours are
classified into explosion groups IIA, IIB and IIC depending on the energy required for ignition. The ATEX CTP belongs to explosion group IIC, which includes extremely flammable gases such as Hydrogen and Acetylene. Dust materials are classified in a similar way, with explosion groups IIIA, IIIB and IIIC depending on the size and conductivity of the dust particles. All ATEX equipment manufactured by Euchner belongs to explosion group IIIC, which even includes dust containing carbon. The ATEX CTP range also achieves Cat4/PLe in accordance with EN ISO 13849-1. An extra feature is the ability to
‘code’ the actuator to the switch, thereby preventing possible manipulation or tampering of the safety circuit as highlighted within EN-ISO-14119. Because of the monitored guard-locking function, the CTP switch is suitable for applications with extended run-down times or even where an inert gas purge is required prior to operator or maintenance personnel access. The robust housing makes the unit especially suited for harsh environments. Its compact design permits
space-saving guard mounting with a locking force of up to 3,900N. Hinged actuators make it possible to use the CTP locking solution on very small radii doors, while for applications where full body access is required
Euchner also produces a variant with a manual escape-release system built in. Euchner
22 MAY 2021 | PROCESS & CONTROL
www.euchner.co.uk
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