DUST COMBUSTABILITY (GROUP A/B)
DANGEROUS SUBSTANCES AND EXPLOSIVE ATMOSPHERES REGULATIONS
‘ATEX’ is an abbreviation of the French - ATmosphere EXplosibles – or Explosive Atmospheres. It is a Directive from Europe to ensure that all Member States create appropriate legislation so that the health and safety of employees from an explosion caused by the work activity is reduced. It is implemented to ensure that all States have a ‘Level Playing Field’ and all are working to the same, or similar, level of risk.
There is also another Directive – the Chemical Agents Directive (CAD). This is another means of preventing injury to employees. However, whereas the ATEX Directive tends to concentrate on the ‘workplaces’, CAD covers everything else.
The UK Government, by the Health and Safety Executive (HSE) has combined the relevant parts of both Directives into the Dangerous Substances and Explosive Atmospheres Regulations 2002. These were then modified to bring in (from CAD) storage of gases under pressure, and liquids corrosive to metals. (The latter – liquids corrosive to metals – seems ‘all encompassing’ but is intended to cover corrosion of metal in supporting structure, to try to prevent a building collapse injuring employees.)
However, it can also be seen that the risk of an explosion to persons is not ‘European Union-specific’. Companies in other countries (outside the UK and Europe) can have the same, or at least similar, risks. Hence why a better term for a DSEAR risk assessment may be SAPIFE: a ‘Structured Assessment for the Prevention of Industrial (flash) Fires and Explosions’ – SAPIFE.
Using the term ‘DSEAR’ acknowledges that the assessment is restricted to the UK. However, it should not be thought of that way, but as a structured method of assessing risks of a flash fire or explosion and whether they can affect persons.
Also, whilst DSEAR considers safety of employees, it does not, directly or indirectly, consider the safety of non-employees- contractors, visitors, off-site persons, etc. Again, though, in some way or other, the risks of an explosion to a non-employee are as serious (if not more serious) than to an employee. Hence the assessments should really go beyond what the ATEX and CAD Directives originally intended.
It is worth noting that Member States can be prosecuted by the European Union for non-compliance with the ATEX Directive. Companies can be prosecuted by the Member States themselves for non-compliance with the local legislation- in the UK this would, obviously, be DSEAR.
DSEAR is, in effect, a risk assessment, in that a hazard has to be present - usually the presence of a flammable atmosphere - and then the effect of the ignition of that flammable atmosphere is assessed as a part of the risk assessment - how likely, who could be hurt, how severely, what can be done to prevent it?
This is a hierarchical risk assessment and it should be ensured, in the first place, that a flammable atmosphere is prevented, as far as reasonably practicable.
(With this hierarchical approach, prevention of the existence of an exothermic chemical reaction is the priority.)
These do seem simplistic, but, again, if the hierarchical approach is followed, risks should all be reduced to a level that is as safe as reasonably practicable.
As far as a flammable atmosphere is concerned, if it cannot be prevented, then an assessment of ignition sources is undertaken. This usually entails a hazardous area classification and an ignition risk assessment (an electrical risk assessment and a 'non-electrical' risk assessment) is then prepared to reduce the risk to persons from ignition of the flammable atmosphere.
If, though, there still remains an 'unacceptable' risk, then 'protection of the people' becomes paramount and explosion protection should be considered.
The simplest explosion protection method is 'safety by position'. This means that if the plant does explode, no one is in the vicinity to be affected by the explosion. This is a business risk, but as explosions are not very frequent in all industries, the financial risk may be acceptable to some companies.
Other, more expensive, means of mitigating the effects of an explosion occur. However, the risk assessment should be able to determine which one or ones should be considered further on a 'reasonably practicable' basis.
This is where Sigma-HSE can assist. We can undertake risk assessments in a holistic way to cover employees and non-employees, in UK, European and non-European sites, explosive atmospheres & chemical reactions, storage of gases, and storage of liquids corrosive to metals, and then determine what reasonably practicable recommendations should be made for the company to consider, which would then reduce the level of risk to persons to one that is as low as reasonably practicable.