Safety In Explosive Atmospheres

Safety In Explosive Atmospheres

From grain flour to vehicle paint spraying, when things go wrong in explosive atmospheres they have a tendency to go spectacularly wrong, extremely quickly.

When it comes to working in environments with the potential for explosions, the stakes have always been high. While following safety procedures is of course important in any industry, just one check missed in an explosive atmosphere can lead to anything from serious injury to death, and catastrophic failure – as the atmosphere’s name would suggest – from explosions. Fortunately, using the right equipment can make a vast difference.

Explosive atmospheres are defined in the Dangerous Substances and Explosive Atmospheres Regulations 2002 (DSEAR) as a mixture of dangerous substances with air, under atmospheric conditions, in the form of gases, vapours, mist or dust in which, after ignition has occurred, combustion spreads to the entire unburned mixture. The aforementioned ‘atmospheric conditions’ are more generally referred to as ambient temperatures and pressures. These will be found in the ranges of –20°C to 40°C and 0.8 – 1.1 bar pressure, respectively.

An explosion is any uncontrolled combustion wave. Many of us will already be familiar with the Fire Triangle. Just in case you’re not, it’s the name for the three precursor elements that facilitate fires. In order to create an explosion the environment will need to have:

  • Fuel – an explosive gas such as hydrogen
  • An oxidiser – such as the oxygen in air
  • A source of ignition energy – such as a hot surface or an electrical spark, even just from flicking on a light switch

    In addition to this, two further facets are required: something to mix the fuel with the oxidiser (such as the turbulence created in a gas leak under pressure); and containment. It is, however, common industrial practice to use the term ‘explosion’ for both confined and unconfined combustion.

    Activities that produce explosive or potentially explosive atmospheres take place in many workplaces; for example, places handling fine organic dusts such as grain flour or wood, and in environments that solvents, varnishes, flammable gases (such as liquid petroleum gas) and paints are used; think paint spraying, for example.

    In process industries, many explosions take place due to a lack of proactive safety implementation. To avoid this, the following strategies can be adopted:

  • Hazardous area classification and explosive zones identification
  • Execution of risk assessment
  • Special audits like electrical safety audit can be implemented
  • Identification of appropriate control measure