Explosion protection according to ATEX guidelines

An important area of safety technology is protection against explosions. Effective explosion protection should prevent damage to people, machines and systems. Products and equipment in potentially explosive atmospheres in the European Union must comply with the requirements of the ATEX guidelines. Pumps and high-pressure solutions are also subject to these guidelines. Further regulations and certifications exist for use outside the European Union.

Definition ATEX

The abbreviation ATEX stands for the French term ATmosphères EXplosibles (explosive atmospheres). The ATEX Directive regulates the aspects of explosion protection in the European Union and comprises the two Directives 1999/92/EC (Operational Directive) and 2014/34/EU (Product Directive).

Primary, secondary and tertiary explosion protection

The ATEX guidelines define a specific sequence for the various explosion protection measures.

ATEX guidelines

The ATEX Directive comprises the two guidelines 1999/92/EC (Operational Directive) and 2014/34/EU (Product Directive). The ATEX Product Directive 2014/34/EU contains the rules for placing equipment and products on the market in potentially explosive atmospheres. It applies not only to electrical equipment and machines, but also to non-electrical components such as pump mechanisms or couplings. These can also present ignition hazards due to inadmissible heating. In addition to the main objective of protecting people from explosions and their effects, the guideline is also intended to remove barriers to trade.

The guideline lists various requirements that manufacturers of products must observe. Compliance with the Machinery Directive must be demonstrated by means of appropriate conformity assessment procedures. Only devices and components that comply with the ATEX Product Directive may be used in potentially explosive atmospheres. Stationary or mobile machines, operating materials, equipment and control parts as well as protective devices are considered as devices. Components are parts which themselves do not fulfill an autonomous function.

Zone classification of potentially explosive atmospheres according to ATEX

ATEX divides hazardous areas into different zones depending on the duration and frequency of the occurrence of hazardous explosive atmospheres. These zones are:

In Zone 0 hazardous explosive atmospheres as a mixture of vapors, mists or flammable gases and air are present frequently, permanently or over long periods of time.

In Zone 1 hazardous explosive atmospheres consisting of a mixture of vapors, mists or flammable gases and air form only occasionally during normal operation.

In Zone 2 dangerous explosive atmospheres as a mixture of vapors, mists or flammable gases and air occur only briefly or not at all in normal operation.

In Zone 20, a cloud of combustible dust in the air is often present as a hazardous explosive atmosphere, either permanently or for long periods of time.

A cloud of combustible dust in the air forms only occasionally as a hazardous explosive atmosphere in normal operation in Zone 21.

The hazardous explosive atmosphere consisting of combustible dust in the air does not form in Zone 22 in normal operation or only forms for a short time.

Typical ignition sources

Ignition sources are capable of igniting dangerous explosive atmospheres and triggering explosions. Depending on the energy of the ignition source and the properties of the explosive atmosphere, the ignition sources have different ignition capability and effectiveness. Typical ignition sources are:

  • hot surfaces such as live conductors in windings of motors, bearings or shaft bushings
  • flames and hot gases as they occur during cutting or welding
  • mechanically produced sparks such as during grinding processes
  • electrical installations with sparks and arcs by opening and closing circuits or by short-circuiting
  • electrical compensation currents
  • electrostatic discharges
  • lightning
  • electromagnetic waves in different frequency ranges
  • ionizing radiation
  • ultrasound
  • adiabatic compression and shock waves
  • exothermal reactions including spontaneous combustion of dusts

Explosion protection for high pressure technology

Various technical solutions and components are used for explosion protection of pump systems and high-pressure solutions. For example, capsule solutions such as flameproof housings "Exd" or the pressurized enclosure "p" are often implemented in the systems. Drive systems consist of frequency inverter-controlled Exd, Exde and ExnA three-phase motors (LV and MV). Exde control boxes are provided for operation and monitoring in harsh environments.

Explosion-proof Exi-, Exe-field distributors are made of glass fiber reinforced plastic or stainless steel. Further components for explosion protection of high-pressure technology are Ex installation system technologies such as intrinsically safe circuits, conduit installations according to NEC 505, fieldbus technology, pressure, differential pressure, flow and level transmitters and switches as well as safety barriers and MMC monitoring systems.

International differences in explosion protection

The ATEX directives are only binding within the European Union and are not recognized everywhere. Numerous other explosion protection regulations and certifications exist worldwide. These are for example the National Electrical Code (NEC) in the USA such as NEC500 and NEC505 as well as IECEx, CQST, NEPSI, TR CU ATEX (formerly GOST), KOSHA, KGS, UL/CSA, CCOE or IMMETRO.

In order to offer and operate explosion-protected high-pressure solutions or pump systems worldwide, extensive knowledge of local regulations and requirements is required. URACA has an extensive body of knowledge in this area and, in addition to ATEX products, offers explosion-protected solutions with numerous other certifications. If you have any questions about explosion protection, contact the experts at URACA now.