Sigma-HSE Newsletter - September 2024
FREE On-Demand Webinar: Mapping the Route to Protection Against Dust Explosions
There is no “one size fits all” approach to managing the risks associated with combustible dusts.
The legislation states that if you handle dusts or powders, you must ensure that the design of your protection systems (venting, containment, or suppression) is appropriate, or confirm if a material is appropriate for use in processes within an established protection system. But how and where do you start?
Whether you’re just getting started with combustible dusts or are an explosion protection expert, it’s important to understand the route to maintain safety in the workplace.
In this webinar Mike Weaver, Associate Director at Sigma-HSE and Sam Ayres, Sales Engineer at StuvEx International, discuss the route from dust testing and risk assessments through to selection and implementation of an explosion protection system.
What you’ll learn:
Where: Online, just register and watch for free HERE .
The Importance of DSEAR and Dust Testing for your LEV Systems
Dust in the workplace can be a nuisance and a hazard which you need to control for the health and safety of your workers.
As a starting point, it is important to know the legal parameters that govern your specific hazard. The ‘COSHH Essentials’ tool is a good start if operators are in the immediate vicinity and might inhale toxic substances. Good information can also be found in INDG408 Clearing the air or HSG258 ‘Controlling airborne contaminants at work’.
If your dust is flammable , then your workplace would be subject to the Dangerous Substances and Explosive Atmospheres Regulations (DSEAR) .
In normal circumstances, operators will not be exposed to explosive dust clouds as this will exceed COSHH control levels, but there are, however, two exceptions.
Normal operations: Exception one
While COSHH is applicable to background dust concentration and expected surges of dust associated with specific tasks, DSEAR is applicable to ‘foreseeable abnormal operations’.
This would include scenarios such as fan failure causing extraction to stop, a torn ‘big bag’ (also referred to as a flexible intermediate bulk container (FIBC)) or an inflatable seal suddenly failing causing the contents of a mill to be released into the work area.
Normal operations: exception two
The second exception is when an LEV is used to control dust for COSHH purposes. The unintended consequence of dust extraction is that the finest fractions are removed and collected in explosive concentrations at the dust collector.
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For most manufacturing situations, explosive dust clouds are only found inside the equipment. Some examples are a hammer mill or various types of dryers. However, LEV systems are often required to protect operator health. These systems provide a localised ‘vacuum’ to remove dust from the operator’s location. Given that the finest fraction is most likely to be airborne, the extracted air contains mostly fine dust. Any ignition source introduced to this environment could be devastating and suitable measures must be put in place to handle these potential issues.
Dust is a common hazard in many workplaces and industries, and it can pose serious risks to both workers’ health and safety and the environment. If you are handling flammable dusts then as part of a DSEAR risk assessment Sigma-HSE would identify such hazards and provide guidance on suitable methods for mitigating these risks
Identify Potential Hazards and Support Your DSEAR with a HAZID
The Hazard Identification (HAZID) study is a powerful and effective risk assessment methodology that can help organisations identify potential hazards and take steps to mitigate or eliminate them.
Whether used as part of the design phase or during the facility’s lifetime, it is a proactive approach that allows for the identification of hidden or latent hazards and can be used as a basis for more detailed risk assessments. Organisations that are looking to improve their risk management practices should consider using HAZID to reduce their overall risk.
Previously, we discussed how a HAZID can be completed before a DSEAR (Dangerous Substances and Explosive Atmospheres Regulations) assessment as it allows for the identification and evaluation of potential hazards and risks in areas that need further investigation during the DSEAR.
However, completing a HAZID after a DSEAR assessment can be used to enhance the evaluation of hazards and risks in a more holistic manner.
As a HAZID is broader in scope, the identification and evaluation of wider hazards (beyond those directly related to dangerous substances and explosive atmospheres) can be undertaken. As a result, risks related to equipment failure, human error, external factors, environment, mechanical, and operational risks can all be considered.
The multidisciplinary HAZID team can also use previous DSEAR findings to ensure that all relevant scenarios involving hazardous substances are considered. This inevitably leads to a more holistic understanding of site risks and ensures that the measures identified in the DSEAR are robust when viewed in the context of site wide operations.
Talk to Sigma-HSE about upgrading your DSEAR assessment to a HAZID team project and create a safer working environment for your staff.
From the Engineers’ Desk
Highly Flammable Liquids and Nitrogen Inertion
We recently encountered a client who was processing on a pilot scale with around 20 litres of a highly flammable liquid that was also insulating. The nature of a highly flammable fluid is that there is a flammable vapour above the liquid surface at room temperature. Unlike conductive liquids in earthed, metallic vessels, an insulting fluid cannot be earthed. Insulating fluids can accumulate electrostatic charge from the shear encountered during pumping, agitation and especially from filtering. If the charge difference equalises, ignition of this flammable vapour is possible.
So, if ignition sources cannot be eliminated, the flammable atmosphere must be eliminated. The liquid surface was open while being filled, so flammable vapours could be removed by local extraction ventilation. However, when the vessel was closed, nitrogen inerting was the only option.
Resources Library
Learning from our Process Safety Experts
To access our repository of technical articles and on-demand webinars, providing a wealth of insight into mitigating fire and explosion risk, check out our website resources page.