IEC 60079-31:2013

Overview

IEC 60079-31:2013 is an international standard developed by the International Electrotechnical Commission (IEC) that addresses the requirements for electrical equipment used in explosive dust atmospheres. Specifically, it focuses on equipment dust ignition protection through enclosure type "t". This standard governs the design, construction, and testing of electrical equipment and Ex Components to ensure safe operation where combustible dusts may be present.

This 2013 edition replaces the 2008 version, introducing technical revisions such as updated surface temperature measurement protocols and enhanced protection measures for arcing and sparking parts within the enclosure. IEC 60079-31:2013 supplements IEC 60079-0 and overrides its general requirements when conflicts arise.

Key Topics

• Scope and Application
  IEC 60079-31 targets electrical equipment with enclosures designed to limit surface temperatures and prevent ignition in explosive dust atmospheres. The standard excludes dusts that do not require atmospheric oxygen (such as certain explosives) and pyrophoric substances. It also does not apply to equipment used in mining environments affected by firedamp or combustible dust.

• Protection Levels and Design Requirements
  The standard defines various levels of protection around enclosure design including dust exclusion and thermal control. Equipment protection levels (“ta”, “tb”, “tc”) impose specific requirements such as:

  • Maximum allowable surface temperatures on external and internal components
  • Mechanically robust joints and sealing methods to prevent dust ingress
  • Overpressure capabilities to withstand internal explosions without failure
  • Additional safeguards for arcing or sparking parts, especially under “ta” protection

• Construction and Testing
  Strict guidelines cover critical construction elements like threaded joints, gaskets, seals, cable glands, and entry points. Type tests (including dust exclusion tests and thermal tests) and routine verification ensure the equipment maintains integrity under operational stresses.

• Marking and Compliance
  Clearly defined marking requirements indicate equipment group classification, ingress protection rating, and the maximum surface temperature limit. These markings aid users and certifiers in confirming equipment suitability for explosive dust environments.

Applications

IEC 60079-31:2013 is essential for manufacturers, safety engineers, and facility operators working in industries where explosive dust atmospheres are present, including:

• Chemical manufacturing plants handling combustible powders
• Food processing industries exposed to flour and grain dust
• Pharmaceutical production environments with dust hazards
• Woodworking facilities generating wood dust
• Metalworking operations producing fine metal dusts

The standard ensures that electrical equipment deployed in these environments prevents ignition and thereby reduces the risk of fires and explosions. Compliance with IEC 60079-31 also assists organizations in meeting international safety regulations and protecting personnel and assets.

Related Standards

• IEC 60079-0: General requirements for electrical equipment in explosive atmospheres
  IEC 60079-31 supplements and modifies the general provisions laid out in IEC 60079-0, which covers fundamental safety principles for all Ex equipment categories.

• IEC 60079 Series
  Other relevant standards in the IEC 60079 series address diverse protection methods, such as intrinsic safety (IEC 60079-11), flameproof enclosure (IEC 60079-1), and pressurized enclosures (IEC 60079-2). Together, they form a comprehensive framework for controlling ignition risks associated with explosive atmospheres.

• ISO/IEC Directives
  The standard aligns with ISO/IEC directives to ensure consistency and harmonization in international electrotechnical standardization.

Adopting IEC 60079-31:2013 facilitates robust dust ignition protection by enclosure "t", helping organizations minimize hazards linked to explosive dust atmospheres and enhance operational safety worldwide.