ATEX 137 - European Guidelines for Explosion Safety
One of the primary objectives of the European Commission is to improve the safety and health of workers at work. All member states agreed on the following legal and general principle: ‘Member states shall pay particular attention to encouraging improvements, especially in the working environment, as regards the health and safety of workers, and shall set as their objective the harmonisation of conditions in this area, while maintaining the improvements made’. This principle has been formalized as Directive 89/391/EEC (the Framework Directive) on the June 12, 1989.
Within this frame work directive there is a directive 1999/92/EC which sets out to improve the health and safety protection of all workers potentially at risk from explosive atmospheres. This directive, better known as ATEX 137 (ATmosphères EXplosives), indicates minimum requirements and is in force for all new or existing hazardous area equipment made available for use after 30 June 2003. However after June 30, 2006 also all existing hazardous area work places must comply with the appropriate minimum requirements of ATEX 137.
Article 4 of directive 99/92/EC obliges you as converter to assess the specific risks arising from explosive atmospheres, taking in account:
- The likelihood that explosive atmospheres will occur and their persistence,
- The likelihood that ignition sources, including electrostatic discharges, will be present and become active and effective,
- The installations, substances used, processes, and their possible interactions,
- The scale of the anticipated effects.
As a converter of SABIC’s polyolefins you will need specific dust explosion parameters for this assessment. You can find the relevant information at http://polymers.sabic-europe.com using our “search our products” option.
Explanation of the relevant resin parameters
Maximum explosion pressure – Maximum pressure occurring in a closed vessel during the explosion of a specific explosive atmosphere determined under specific test conditions.
dust explosion class - Dust explosion causes a pressure increase in a closed vessel 
.
Dust is classified into dust explosion classes Based on the in a volume of 1 m3 (the so-called Kst value):
| Dust explosion class | KSt value in bar · m · s-1 |
|---|---|
| St 1 | > 0 to 200 |
| St 2 | > 200 to 300 |
| St 3 | > 300 |
Ignition Temperature of a dust cloud - Lowest temperature of the hot inner wall of a surface at which ignition occurs in a dust cloud in air contained therein.
Minimum Ignition Temperature of a dust layer, MIT – Lowest temperature of a hot surface at which ignition occurs in a dust layer of specified thickness on this hot surface under specified test conditions.
Remark: Polyolefins melt before ignition of the dust layer can occur.
Lower Explosion Limit, LEL – Range of the concentration of a flammable substance in air, within which an explosion can occur.
Minumum Ignition Energy, MIE - Lowest energy which is sufficient to effect ignition of the most easily ignitable explosive atmosphere under specified test conditions.
Volume Resistivity – The resistance of a body of unit length and unit width commonly expressed in Ωm.
