Overview
IEC TS 60079-42:2019, titled "Explosive atmospheres - Part 42: Electrical safety devices for the control of potential ignition sources for Ex-Equipment," is a Technical Specification published by the International Electrotechnical Commission (IEC). This standard provides detailed guidance for manufacturers and engineers on the use of electrical safety devices designed to reduce the likelihood that potential ignition sources within electrical equipment (Ex Equipment) become effective in explosive atmospheres.
These safety devices play a critical role in controlling ignition sources arising from both electrical and non-electrical equipment operating in hazardous environments. Importantly, IEC TS 60079-42:2019 helps ensure that such devices perform the intended safety functions reliably, supporting compliance with broader standards in the IEC 60079 and ISO 80079 series related to explosion protection.
Key Topics
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Scope and Application
The standard applies to electrical safety devices used to mitigate ignition risks by controlling potential ignition sources, whether originating from the equipment itself or from associated components like sensors and logic systems. It also covers assessment of safety devices independently from specific Ex Equipment.
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Safety Function Specifications
It details the requirements for specifying and achieving safety integrity levels necessary for ignition risk reduction. Both simple and complex safety devices are considered in the design and testing processes.
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Ignition Prevention Concepts
The document outlines methods for ignition risk reduction and defines minimum Risk Reduction Factors (RRF) required for safety devices that control ignition sources.
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Testing and Verification
Provides guidance on type testing and proof testing of safety devices to verify their functional safety and reliability in explosive atmospheres.
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Marking and Instructions
Specifies marking requirements and user instructions to ensure proper identification, usage, and maintenance of safety devices.
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Exclusions
The specification excludes mechanical control equipment, gas detection systems, devices preventing the formation of explosive atmospheres (e.g., inerting, ventilation), and explosion mitigation systems.
Applications
IEC TS 60079-42:2019 is highly relevant for:
- Equipment Manufacturers developing electrical apparatus intended for use in hazardous areas classified as explosive atmospheres.
- Safety Device Designers focusing on devices that control potential ignition sources to enhance equipment protection levels.
- Process Industry Operators who implement safety control systems to prevent ignition and ensure compliance with explosive atmosphere regulations.
- Safety Engineers assessing safety-integrity requirements and operational reliability of ignition control devices.
Typical use cases include the integration of safety devices with temperature control systems on Ex motors, overload protection devices, and control units for high-temperature surfaces or current-dependent safety controls. The standard includes practical examples like temperature-limiting devices, motor temperature control sub-functions, and bucket elevator ignition hazard assessment, illustrating how ignition risk can be effectively minimized in challenging industrial environments.
Related Standards
IEC TS 60079-42:2019 complements and should be used in conjunction with relevant standards within the IEC 60079 series and ISO 80079 series, including but not limited to:
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IEC 60079 Series
These core international standards cover equipment and protective systems intended for use in explosive atmospheres, providing broad guidance on explosion protection techniques and specific types of protection.
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ISO 80079 Series
Focuses on equipment for explosive atmospheres and includes standards for non-electrical components and additional protective measures.
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IEC 61508 and IEC 61511
Address functional safety of electrical/electronic safety-related systems and safety instrumented systems relevant for the design and assessment of safety devices.
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ISO/IEC Directives
Provide guidance on standardization principles, which support the development of IEC TS 60079-42 as part of an internationally harmonized framework.
By integrating IEC TS 60079-42:2019 into safety management and equipment design processes, organizations can enhance the safe operation of electrical equipment in explosive atmospheres, prevent ignition, and comply with global safety regulations effectively.
Keywords: IEC TS 60079-42, explosive atmospheres, electrical safety devices, ignition prevention, Ex Equipment, safety function, explosion protection, hazardous areas, functional safety, risk reduction, equipment protection level, IEC 60079 series, ISO 80079 series.