Flammable and Explosive Atmospheres

The Dangerous Substances and Explosive Atmospheres Regulations (DSEAR – SI 2002/2776) require protection of people in workplaces from the risk of fire and explosion.

This includes flammable substances and explosives, highly exothermic or decomposition reactions, pressurised gas cylinders (even if non-flammable), oxidisers and metal corrosive substances. Some chemicals may not present an explosion risk in their supplied or stored form but could become hazardous during processing. Others, such as some caustics, can self-ignite if stored incorrectly.

Hazardous substances can be in any form – gas, solid, liquid or plasma – and may be produced deliberately, such as an intermediary process, or perhaps accidentally due to a spill or unintended mixing operation. The CLP labelling on a container is a good starting point, but on its own is insufficient.

What to consider?

• What substances are present?

• What hazards are possible?

• Can it be prevented by design?

• Can the severity be minimised?

• Can harm be avoided or minimised, e.g. via procedures?

• How should people be made aware of potential hazards?

• What training is required?

• Are emergency procedures suitable?

How Hazardous Inventory be managed?

The Hierarchy of Controls triangle provides a useful framework:

Hierarchy of Controls (from most to least effective)

• Elimination (Physically remove the hazard)

• Substitution (Replace the hazard)

• Engineering Controls (Isolate people from the hazard)

• Administrative Controls (Change the way people work)

• PPE (Personal Protective Equipment)
  

If a hazardous substance cannot be removed from a process via elimination or avoiding creation, then investigate substitution, segregation and other control measures to help reduce the likelihood of a dangerous occurrence.

Personal Protective Equipment should be considered the LAST line of defence against harm!

The 6 Engineering DSEAR Compliance Approach:

1: Consider Hazardous Inventory

We visit your site, discuss your operations and processes, review substance documentation and collate into a DSEAR risk compliance list. To gather information we speak with personnel at all levels to gain a cohesive picture across your operations.

2: Risk Assessment

We use site walkarounds and document review findings to populate DSEAR risk assessment worksheets, and then facilitate a workshop with your staff – on site or remotely – to consider hazards, existing safeguards, and identify areas for improvement.

Our approach goes further: effectively tier for increasing risk complexity and severity for undocumented DSEAR; the workshop is only the beginning – we do the most on the site tour.

Only when a hazard is recognised and understood, controls can be designed. Our DSEAR Workshops deliver a deeper understanding of safety systems which then are more robust. Based on understanding garnered from the UK’s health and fire inspectors, 6 Engineering want to support you in your journey.

3: Risk Assessment Outcomes

A “basis of safety” is a hazard mitigation ethos. These come in a number of formats and are applied across the world in all manner of industries. Understanding which you now own (e.g. such as venting and fuel stabilisation). Some examples relating to DSEAR include:

Control of availability

• Reduce combustible dust build-ups and liquid spillages

• Ventilation – diluting the flammable substance such that there isn’t sufficient fuel to ignite
  

Control of oxygen availability

• Inerting – flooding a storage tank (commonly nitrogen) to exclude oxygen from the storage container or reaction vessel

• Closed-loop or single-use gases (e.g. acetylene) can ignite or explode simply with the presence of oxygen or by using another oxidiser such as chlorine, and therefore this is not a guaranteed solution.
  

Control of ignition sources

• Earthing – avoid electro-static spark generation through use of ATEX-rated electrical equipment and requiring conductive clothing, shoes, cleaning implements and tools

• Heat generation – use equipment which even in failure cannot generate sufficient heat to ignite the substances present (e.g. clutches, springs, pump couplings and motor internals)
  

Hazardous Area Classification

Despite best efforts, systems still have leak points. How can it be managed safely?

Hazardous area classifications identify the type of release, the material characteristics and their control measures. When applied correctly, they help identify areas of risk and increase understanding of tools and procedures that keep people safe.

We produce calculations, summary tables and sketches illustrating leak scenarios and zone shapes and extents. Consequence modelling can be performed for larger releases if required.

Empower Your People

At 6 Engineering we pride ourselves on our industry-leading approach to DSEAR assessments, fire risk assessments and hazardous area classifications. We are proactive and passionate in our approach – bringing knowledge and experience with YOU.

We deliver consistent results when reviewing relevant substances and operations, often running a DSEAR risk assessment workshop with YOUR personnel, so everyone involved is “bought in” and informed.