IEC 60079-18:2014

Overview

IEC 60079-18:2014 - Explosive atmospheres - Part 18: Equipment protection by encapsulation “m” sets the specific requirements for the construction, testing and marking of electrical equipment, parts and Ex components using encapsulation (type of protection “m”) for use in explosive gas atmospheres and explosive dust atmospheres. This edition (4.0, 2014, with the July 2018 corrigendum included) applies to encapsulated equipment with rated voltages up to 11 kV and is to be read together with IEC 60079-0:2011. It supplements and modifies general requirements in IEC 60079-0; where conflicts occur, IEC 60079-18 takes precedence. The standard excludes certain materials (e.g., dusts that do not require atmospheric oxygen for combustion and pyrophoric substances) and does not address risks from flammable or toxic gas emissions from dust.

Key topics and technical requirements

• Scope and EPLs: Defines equipment protection levels (EPL) such as ma, mb, mc and additional requirements for higher protection levels.
• Compounds: Specification and properties of encapsulation compounds (e.g., water absorption, dielectric strength, thermal conductivity) and reference to basic compound requirements (Annex A).
• Temperatures: Determination of limiting temperatures, maximum surface temperatures and compound temperature limits.
• Construction rules: Fault determination, isolating components, infallible separation distances, free space inside encapsulation and minimum compound thicknesses (including rules for windings and multi-layer printed wiring boards).
• Special parts: Requirements for switching contacts, external connections, protection of bare live parts, cells/batteries (gassing, charging, polarity protection), and protective devices (electrical and thermal).
• Testing and verification: Type tests (water absorption, dielectric strength, thermal endurance, cable pull, pressure tests for Group I/II, etc.) and routine visual/dielectric verifications.
• Marking: Mandatory marking details for encapsulated “m” equipment.

Applications

• Use this standard when designing or certifying encapsulated electrical equipment intended for hazardous locations where explosive gases and/or combustible dusts may be present.
• Typical industries: oil & gas, petrochemical, chemical processing, mining, grain handling, pharmaceuticals, and utilities.
• Ensures safe encapsulation design to prevent ignition sources and meet regulatory and certification requirements.

Who should use this standard

• Equipment designers and electrical engineers developing encapsulated Ex components
• Manufacturers of motors, sensors, junction boxes and control equipment for hazardous areas
• Test laboratories, certification bodies and compliance officers
• End-users specifying safe equipment for explosive gas atmospheres and explosive dust atmospheres

Related standards

• IEC 60079-0 (general requirements) - mandatory companion document
• Other parts of IEC 60079 series for alternate protection types and specific applications

Keywords: encapsulation "m", explosive gas atmospheres, explosive dust atmospheres, IEC 60079-18, equipment protection, Ex equipment.