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Intrinsic Safety

Intrinsic safety barrier

This guide provides a comprehensive overview of intrinsically safe measurement instrumentation, crucial for ensuring safety in hazardous environments. It explains the core principles of intrinsic safety, focusing on limiting electrical and thermal energy to prevent ignition in potentially explosive atmospheres.

The guide details the key components of an intrinsically safe system, including sensors, barriers, and cabling, and how they interact to safeguard personnel and equipment. It also explores the importance of certification, regulatory compliance, and proper installation and maintenance practices. Finally, the guide illustrates the diverse applications of intrinsically safe measurement instrumentation across various industries, highlighting its significance in protecting against the risks of explosions and fires.

  • Intrinsic safety prevents explosions by limiting energy in hazardous areas, unlike containment methods.
  • Systems comprise a hazardous-area sensor, safe-area barrier, and connecting cables. The barrier restricts energy flow.
  • Sensors must be certified for the specific hazardous area classification to prevent ignition.
  • Compliance with regulations is mandatory; proper installation and maintenance are crucial.
  • Intrinsically safe instrumentation is used across diverse industries with explosive atmospheres.

Browse intrinsically safe measurement instrumentation by product type for use in hazardous areas with an intrinsic safety barrier.

The Essence of Intrinsic Safety

Intrinsically safe measurement instrumentation plays a crucial role in ensuring safety within hazardous environments. These environments, often found in industries like chemical processing, oil and gas, and mining, may contain potentially explosive atmospheres. The core principle of intrinsic safety is to limit the electrical and thermal energy within these hazardous areas, preventing ignition of flammable gases, vapors, or dust. This is achieved by carefully designing and certifying equipment to ensure that even under fault conditions, the energy released is insufficient to cause ignition. This approach differs from other protection methods, such as explosion-proof enclosures, by preventing the explosion from occurring in the first place.

The Role of Barriers and Sensors

A typical intrinsically safe measurement system consists of a sensor located within the hazardous area, connected via cables to a barrier device situated in a safe area. The barrier, which can be either a Zener diode barrier or a galvanic isolator, acts as a safeguard. It restricts the amount of electrical energy that can travel into the hazardous area, effectively limiting voltage and current to intrinsically safe levels. Zener barriers divert excess energy to ground, while galvanic isolators use transformers to provide isolation and limit energy transfer. The selection of the appropriate barrier type depends on the specific application requirements, including the type of sensor, the signal characteristics, and the safety requirements of the hazardous area.

Sensor Design and Certification

The sensor itself is a critical component. It must be designed and certified to operate safely within the designated hazardous zone. Certification bodies, accredited by relevant government agencies, rigorously test and assess the sensor’s design and performance to ensure compliance with stringent safety standards. This certification process involves evaluating the sensor’s electrical parameters, its operating temperature, and its construction to ensure that it cannot become a source of ignition. The sensor’s certification details, including its permissible energy levels and installation requirements, are essential for proper system design and installation.

Sensors must be certified for the specific hazardous area classification to prevent ignition. This certification process involves rigorous testing and assessment by independent bodies to ensure compliance with stringent safety standards. Manufacturers seeking to market their intrinsically safe products globally often obtain certifications from multiple national approval bodies to facilitate acceptance in different regions. Some of the most commonly sought-after certifications include:

  • ATEX (Europe): Mandated by the European Union, ATEX certification covers equipment used in potentially explosive atmospheres.
  • IECEx (International): A globally accepted scheme for certification of equipment for explosive atmospheres, providing a basis for mutual recognition between participating countries.
  • UL (North America): Underwriters Laboratories (UL) offers certification and safety testing services for a wide range of products, including those used in hazardous locations.
  • FM (North America): FM Approvals, part of FM Global, provides testing and certification services for industrial and commercial products, with a focus on loss prevention.
  • CSA (North America): The Canadian Standards Association (CSA) offers certification and testing services for various products, including those used in hazardous environments.

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Cabling, Grounding, and Bonding Considerations

The cables connecting the sensor to the barrier are also carefully considered. They must be selected to minimize the risk of energy storage or transfer, and their installation must adhere to specific guidelines to prevent damage or degradation that could compromise safety. Furthermore, the entire system, including the sensor, barrier, and cabling, must be properly grounded and bonded to prevent the buildup of static electricity, which could also serve as an ignition source.

Regulatory Landscape and Compliance

Intrinsic safety standards and regulations vary by region. It’s crucial to consult the local regulations and guidelines to ensure that the measurement instrumentation is compliant. These regulations often specify the types of hazardous areas, the required protection levels, and the certification procedures for equipment used in those areas. Choosing certified equipment from reputable manufacturers is essential for ensuring compliance and maintaining safety. Regular inspection and maintenance of intrinsically safe systems are also critical to verify their continued integrity and proper operation. This includes checking cable connections, verifying barrier performance, and ensuring that the sensor remains within its certified parameters.

Diverse Applications of Intrinsic Safety

Use cases for intrinsically safe measurement instrumentation are diverse. In chemical plants, these systems are used to monitor process variables such as temperature, pressure, and flow in areas where flammable or explosive materials are present. In oil and gas exploration and production, intrinsically safe sensors and transmitters are essential for monitoring well conditions and pipeline integrity in hazardous offshore or onshore environments Mining operations rely on intrinsically safe instrumentation to detect gas levels and monitor equipment performance in underground areas where explosive atmospheres can accumulate.

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Questions & Answers

USA version of ATEX II 2 G

What is ATEX II 2 G classification and what is the USA equivalent?

This refers to the ATEX Ex coding which is the European regulatory directive for using equipment in hazardous areas.

  • II = Non-Mining
  • 2 = Non-Mining: High Protection – Equipment must be safe during regular functioning and likely failures, required for Gas zone 1 and/or Dust zone 21
  • G = Explosive Gas environment

Hazard area equipment is approved by FM Approvals (Factory Mutual) in the USA, and this chart shows a comparison between FM (top) and ATEX (bottom) markings, according to this chart the equivalent FM marking for ATEX II 2 G is:

  • 2 = Division 1, Zone 1
  • G = Class 1 (Gases, Vapours or Liquids)

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