Designing safer solutions for hazardous areas
Author : Lewis Boyland, Middle East Technical Manager, Nuaire
01 December 2022
When operating in potentially hazardous areas, the specification of high-performing, specialised ventilation solutions is more important than ever.
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As technology rapidly advances, the manufacturing industry has witnessed significant improvements in efficiency and quality, but more importantly, in workplace safety. While these developments predominately stem from increasingly stringent health and safety regulations, workplace safety should be more than simply compliance-driven. The implementation of preventative and early detection practices not only helps to prevent work-related injuries, but can also significantly improve ROI and business operations.
This is particularly true for high hazard process industries dealing with toxic chemicals, asphyxiants, flammable gases, and combustible dusts. Workers in these potentially explosive environments are frequently exposed to harmful chemical compounds, or oxygen-deficient atmospheres, which can result in serious health issues, or even death. The presence of electrical equipment in these areas presents an equally dangerous risk, with the potential of igniting a fire or triggering an explosion.
The risk level of an explosion is based on the intensity of volatile compounds, including the frequency and duration of their presence. This probability is represented by classifying the hazardous area into zones. Each zone requires a unique, fit-for-purpose ventilation solution in order to prevent the build-up of toxic substances and effectively maintain a safe environment.
A number of factors are taken into account during the zoning process, including the release source of the toxic and flammable substances and whether these arise from constant activities, from time to time in normal operation, or as a result of an unplanned event.
Then the type of substances present must also be identified, whether it be gases, vapours, combustible dust, flammable liquids or ignitable fibres. Since combustible gases either rise or sink depending on the density of the molecules, this will dictate the positioning of the ventilation system – whether it is located at floor level or up high. Propane, for example, is a heavy molecule which sinks, meaning that the supply and exhaust ventilation for the associated hazardous area must be positioned at floor level.
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Accurate zoning will determine the volume of air needed to dilute, evacuate, or collect the harmful material to maintain a safe environment for workers by mitigating all potential risks. In many cases integrated chemical filtration systems may be required to prevent corrosive and toxic substances from being recirculated. It is also important to note that separate, independent exhaust systems are required for each material, and they must exhaust directly to the outdoors. There is, however, the possibility of exceptions if engineers can verify that different solvents are compatible and can safely share an exhaust system without triggering a hazardous reaction.
Specified ventilation systems must be specially built using a combination of explosion-proof, intrinsically safe, and non-incendive equipment. These ATEX systems are specifically designed to prevent either an electrical or mechanical spark generated by the junction box or motor. Other spark-protection design elements include mitigating the risk of metal-on-metal contact between the impeller, and the outer casing through the use of an anti-spark track.
When it comes to selecting the right supplier, there are just as many factors to consider. It is important to choose suppliers with in-depth knowledge of the stringent environmental guidelines on both a local and international scale, as well as extensive experience in designing for hazardous conditions. What’s more, systems should always be tested to address project-specific installation requirements by a third-party certification provider to verify that the system will effectively and efficiently draw hazardous substances away from the main source and lower the overall concentration of emissions. It is important not to compromise on quality in favour of cost, since doing so can ultimately result in costing more in the event of workplace injuries or property damage.
Another important factor to consider in the design of ventilation systems for hazardous areas is the surface finish of the fans. Moisture, oxygen, temperature, toxic molecules, and air pollution all affect the rate of corrosion of steel. To prevent the degradation of equipment and maximise longevity, industrial fans are specified with special paint grades, coatings or hot dip galvanised steel.
Aside from specialised ATEX ventilation systems, high temperature axial fans are equally important. These systems are specifically engineered to protect lives in the event of a fire, and so should be certified to EN12101-3 for temperatures up to 400°C for two hours. In the event of an emergency, high temperature axial fans are designed to protect workers by maximising valuable time for safe evacuation. Designed to a predetermined fire load with fans strategically located throughout the property, the units work to create a virtual smoke barrier. The barrier limits the spread of smoke and ensures it is cleared quickly and effectively to keep the rest of the area smoke-free.
Finally, there is the consideration of energy efficiency. As the building services industry increasingly focuses on sustainability, many modern manufacturers are striving to create more energy efficient fire safety and ventilation solutions to reduce energy consumption and associated costs. Choice of motors, control electronics, airflow paths both within the fan unit and within the wider system, are of vital importance when defining the energy efficiency of a system. By opting for high performing ventilation solutions that focus on energy efficiency, business owners can maintain performance of systems and comfort of workers while saving costs on energy consumption.
Lewis Boyland, Middle East Technical Manager, Nuaire
As a result of the ongoing drive towards sustainability, we have witnessed a shift towards ventilation on demand (VOD) systems in recent years. These ventilation units use sensors to detect where workers and machines are situated and direct the maximum airflow to these locations. Despite requiring a larger upfront investment and maintenance to ensure sensors are always working, VOD systems offer a more targeted and efficient approach to high hazard ventilation that will work to reduce operating costs in the long term.
As organisations in the industry continue to prioritise worker health and wellbeing, demand for products that support safety, while also delivering on costs, is likely to grow. Fire safety is an ongoing responsibility to protect the health of workers and requires a thoughtful plan – larger than simply installing smoke alarms. It begins with a thorough understanding of the fire vulnerabilities in your business and the spaces you operate. Only then can you identify the highest performing, reliable, and durable systems required for your project.
About the author:
Lewis Boyland, Middle East Technical Manager at Nuaire, has been an integral member of the technical sales team for 8 years. In 2017, Lewis relocated to Dubai to grow the company’s presence in the MENA region by nurturing robust and mutually-beneficial relationships with local consultants. Lewis’ deep expertise are focused on car park and smoke ventilation design, from conceptualisation right through to final design.
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