Intrinsically Safe Knowledge Base
Designing Intrinsically Safe Systems: A Holistic Approach
When it comes to safety in hazardous environments, nothing is more critical than the design and implementation of intrinsically safe systems. These systems are designed to limit the energy available for ignition, so that ignition of a hazardous atmosphere is prevented. One of the leading providers of such systems is the Intrinsically Safe Store. We offer a wide range of intrinsically safe and explosion-proof devices, supporting safety in hazardous areas. Let’s delve into the holistic approach to designing these systems with barriers.
Understanding Intrinsically Safe Systems
Designers create intrinsically safe systems to prevent explosions in hazardous environments, ensuring that the system’s energy is always below the energy required to ignite the atmosphere. They achieve this through the use of barriers that limit the system’s available energy.
The Role of Barriers in Intrinsically Safe Systems
Barriers play a crucial role in intrinsically safe systems. Designers aim to limit the amount of energy that can be transferred from a non-hazardous area to a hazardous area. They achieve this by limiting the voltage and current that the system can receive.
Designing Intrinsically Safe Systems: A Holistic Approach
A holistic approach to designing intrinsically safe systems involves considering all aspects of the system, from the design and installation of the barriers to the operation and maintenance of the system. This approach identifies and mitigates all potential sources of ignition, supporting a high level of safety.
- Design: The design phase involves selecting appropriate barriers for the system and specifying their correct installation based on applicable standards. This includes considering the type of hazardous atmosphere, the electrical characteristics of the system, and the potential sources of ignition.
- Operation: During operation, it is essential to monitor the system to ensure that the barriers are functioning correctly. This includes regular testing and inspection of the barriers and the system as a whole.
- Maintenance: Regular maintenance is crucial to ensure the ongoing safety of the system. This includes regular testing and replacement of the barriers as necessary.
Case Study: Intrinsically Safe Store’s Holistic Approach
The Intrinsically Safe Store is a leading provider of intrinsically safe and explosion-proof devices. We take a holistic approach to safety, offering a wide range of products and services designed to support a high level of safety in hazardous environments. This includes a range of barriers, as well support services to ensure the correct installation and operation of these systems.
What Has Changed in IS System Design?
The principles of intrinsic safety remain constant, but the standards and technology have evolved. Key conformity frameworks like the ATEX Directive, which relies on the IEC/EN 60079 series of harmonized standards, and North American standards (NEC 500/505) are periodically updated to reflect improved safety practices and new research. Modern system design places a greater emphasis on a full loop assessment, including cable parameters and the combined characteristics of all devices, not just the barrier itself. This ensures the entire circuit within the hazardous area is compliant.
Technologically, there has been a significant shift from traditional Zener diode barriers to modern galvanic isolators. While Zener barriers are still effective and widely used, galvanic isolators offer advantages such as eliminating the need for a dedicated, high-integrity intrinsically safe earth ground, which can simplify installation and reduce potential points of failure. They also provide better signal accuracy and noise immunity for sensitive analog loops.
Updated Comparison of Current Barrier Options
Choosing the right barrier is a critical step in the design process. The two primary types are Zener barriers and galvanic isolators. Each has its place depending on the application’s requirements for cost, performance, and installation complexity.
| Feature | Zener Barrier | Galvanic Isolator |
|---|---|---|
| Grounding Requirement | Requires a dedicated, high-integrity IS earth connection, with standards like IEC 60079-14 and manufacturer documentation often specifying a resistance of less than 1 Ohm. | No IS earth ground required. Uses standard instrument earth. |
| Installation Complexity | More complex due to strict grounding requirements. | Simpler, as it eliminates the need for a special ground connection. |
| Signal Accuracy | Can be affected by ground loop noise. Includes series resistance. | High accuracy and immunity to ground noise due to electrical isolation. |
| Power Requirement | Passive device; does not require its own power supply. | Active device; requires a power supply to operate. |
| Initial Cost | Lower per unit. | Higher per unit. |
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Frequently Asked Questions
What is the main difference between a Zener barrier and a galvanic isolator?
The primary difference is how they achieve safety. A Zener barrier diverts excess energy to a dedicated IS ground, while a galvanic isolator uses transformers, capacitors, or optocouplers to create a complete electrical separation between the hazardous and non-hazardous area circuits, eliminating the need for an IS ground.
Can I use any barrier for any hazardous area?
No. The barrier must be certified for the specific hazardous area classification (e.g., Zone 0, 1, or 2; Class I, Div 1 or 2) and gas group (e.g., IIA, IIB, IIC) it will be used in. Furthermore, the barrier’s entity parameters (voltage, current, power) must be compatible with the field device and cabling being used.
How often do intrinsically safe barriers need to be inspected?
Inspection frequency depends on the facility’s policies, environmental conditions, and regulatory requirements. However, IEC 60079-17 recommends periodic detailed inspections (typically not exceeding 3 years) that include checking the integrity of the IS earth connection for Zener barriers and verifying all connections are secure for both types.
Is a holistic design approach more expensive?
While a holistic approach may require more detailed engineering upfront, it often reduces long-term costs. It prevents expensive redesigns, ensures regulatory compliance, minimizes downtime, and, most importantly, supports the highest level of safety, which is invaluable. Proper planning prevents costly errors during commissioning and operation.
Designing intrinsically safe systems with barriers requires a holistic approach that considers all aspects of the system, from design and installation to operation and maintenance. By limiting the energy available to the system, barriers play a crucial role in preventing explosions in hazardous environments. The Intrinsically Safe Store is a leading provider of these systems, offering a wide range of products and services designed to support a high level of safety. Explore our certified IS Barriers for Zone 0/1/2 to learn more about our offerings. For any queries or further information, feel free to talk to an IS systems specialist for a design consultation.