Case Study – DSEAR Design Assessment

Case Study – DSEAR Design Assessment

Background to the case study

As a business, you need to know what substances or systems can present fire and explosion risks in your workplace.

A requirement of DSEAR (Dangerous Substances and Explosive Atmosphere Regulations [DSEAR] 2002) is to identify and classify areas of the workplace where explosive atmospheres may occur. These are then classified into hazardous zones based on the risk of an explosion occurring and protected from sources of ignition by selecting suitable equipment and protective systems.

Because of the nature of anything that falls into the DSEAR category, it is important to consider what would happen if something were to go wrong and have emergency planning in place. It might also be necessary (prudent) to share your plans with the local Fire Service.

In addition, these plans need to be shared with your employees. Employees must be trained to deal with the risks from dangerous substances.

This planning and awareness reduces potential risks and maintains the safety of the business.

Client Requirements

The client is an engineering manufacturer specialising in bespoke equipment and machinery supporting the aviation industry, as well as others. The client was designing a fuel heating system to be supplied to one of the UK’s main aviation companies to undertake a number of specific tests.

This system was not only to heat the fuel above its flashpoint but was to be placed in an area where Zones (as defined by the Dangerous Substances and Explosive Atmosphere Regulations [DSEAR] 2002) were present.


The client wanted to not only assure their client that the design minimised the potential for it to create an explosion but also that it could be installed in such a way that it couldn’t act as a potential source of ignition for any other explosive atmosphere that could be created in the work area.


Ligtas Consultancy worked with the designers to review and improve the designs by identifying secondary release points (leak points) that had the potential to create an explosive atmosphere.

At each of these points, it was ensured that, where possible, the potential was either removed or minimised by a suitable engineered solution. Working this way, the controls at the top of the prescribed Hierarchy of Control within DSEAR could be applied rather than relying totally on protective systems to prevent explosions.

The assessment then considered positioning requirements within the workspace and the existing Zones.


Ligtas had previously undertaken a full Hazardous Area Classification (HAC) of the workspace sometime prior to undertaking this work, so they had the confidence to rely on that assessment. However, a physical inspection of the area was undertaken to ensure nothing had significantly changed between the time of the HAC assessment and this design assessment.

Client Benefits

The client was able to demonstrate that the design had robustly considered the potential risks associated with heating fuel above its flashpoint and minimised the risks of an explosion occurring.

Minimising the need for expensive EX-rated components to be included within the design not only improving the inherent safety of the equipment but also reducing the costs associated with manufacture.


Avoidance of problems that could be caused by the introduction of this new equipment into the existing workspace during the legally required review of the Hazardous Area Classification assessment.

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