What is "Explosion Proof" and When is it Needed?

Explosion Proof (EP) is a crucial requirement for equipment intended for use in hazardous (classified) locations, as stipulated by the National Electrical Code, NFPA 70, Article 500. These locations are known to have potentially ignitable, flammable, or combustible atmospheres, where a mere spark could trigger an explosive reaction. To ensure safety, all electrical components installed in hazardous (classified) locations must be insulated from the atmosphere.

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In electrically classified laboratories, electrical outlets and switches are enclosed in boxes that are intrinsically safe and rated as EP. Additionally, wiring in the lab is completely enclosed in conduit to prevent any sparks or potential ignition sources. Spark resistant construction is an absolute necessity for any equipment installed in these spaces. Components within a hazardous (classified) location must comply with EP requirements as defined by NFPA 70 to mitigate the risk of explosions and ensure the safety of personnel.

What is considered a hazardous (classified) location?

The National Electrical Code (NEC) and National Fire Protection Association (NFPA) 70 classify rooms with potentially explosive or flammable atmospheres as either Class I, II, or III and Division 1 or 2 within each of these classes. Class I locations refer to places where flammable gases or vapors may be present in the air in quantities sufficient to produce explosive or ignitable mixtures. Class II and III locations are rooms with the presence of combustible dust and fibers, respectively, and are not typical of the atmosphere in a laboratory environment.

If a fume hood is situated in an area with any of these electrical classifications, it should be rated as EP, irrespective of the nature of the activities performed inside it. This is because laboratories with a potentially flammable atmosphere must be devoid of any spark potential, including the electrical components situated outside the fume hood&#;s airstream.

What makes a fume hood classified as Explosion Proof?

It is a common misconception that working with a flammable chemical automatically requires an EP fume hood. However, only a small percentage of customers actually need EP fume hoods for their application. Many laboratories can effectively manage flammable chemicals with standard fume hoods that are properly ventilated and meet relevant safety standards.

When determining the need for an EP fume hood in your application, there are a few key factors to consider. Contrary to common misconception, EP hoods are not designed to contain explosions, but rather to minimize the potential for sparks that could ignite a flammable atmosphere.

In fact, most manufacturers define an EP hood as one that has been modified to eliminate spark potential outside the fume hood, reducing the risk of igniting a flammable atmosphere. These hoods are specifically designed to prevent sparks and potential ignition sources from escaping the hood and posing a risk in hazardous (classified) locations.

An EP laboratory hood is equipped with specially designed electrical components, such as EP rated switches, receptacles and internal wiring. The fume hood manufacturer does not supply these EP components, but instead, a licensed electrician installs them on-site in accordance with all state and local codes. For this reason, all EP modified Labconco fume hoods come with an EP rated incandescent light fixture and without bulbs, wiring, switches or duplexes.

Exhaust blowers serving hazardous (classified) locations

Spectrum&#; Fiberglass Reinforced Polyester (FRP) and PVC exhaust blowers are designed to meet the requirements for applications in hazardous (classified) locations, when installed in accordance with ANSI/ASSP Z9.5 and NFPA 45 guidelines. As per NFPA 45, which is the standard for fire protection in laboratories using hazardous materials, exhaust fans used to remove hazardous substances must be located on the roof or exterior of a building. Adhering to these installation guidelines helps ensure the safe operation of exhaust fans and prevent any potential ignition sources from being present inside the hazardous (classified) location itself.

As stated in the American Society of Safety Professionals&#; ANSI/ASSP Z9.5 standard, exhaust fans must conform to AMCA 99 for their construction. According to AMCA 99, exhaust fans that handle potentially explosive particles, fumes or vapors are required to have spark resistant construction for all components within the hazardous air stream, eliminating the risk of ignition.

Labconco&#;s Spectrum FRP and PVC exhaust blowers are designed with the highest level of spark resistant construction, adhering to Type A construction requirements as specified in AMCA 99. This ensures that these exhaust fans meet the safety standards for operation in hazardous (classified) locations, providing an added layer of protection against potential sparks and ignition sources.

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Safety standards help protect assets and also foster a safe workplace. In potentially hazardous environments, equipment must follow particularly strict standards to reduce the risk of an explosion. Here we explain the difference between equipment labeled as intrinsically safe vs. explosion-proof.

What Does it Mean to be Intrinsically Safe or Explosion Proof? 

The terms intrinsically safe and explosion proof may sound similar, but they are very different. Intrinsically safe means that the piece of equipment itself can&#;t cause an explosion. Meanwhile, explosion-proof means that if an explosion did happen, the device would be protected by an explosion-proof enclosure that helps contain explosions and prevent them from spreading. Therefore intrinsically safe refers to explosion prevention, whereas explosion-proof refers to containment. Depending on your industry and working environment, you may need to use one over the other.

Intrinsically safe equipment cuts off thermal or electrical energy once the temperature gets too high in order to stop hazardous areas from catching on fire. These devices are engineered to limit heat generation and avoid causing an ignition due to elevated voltage and current levels. 

For example, intrinsically safe devices will have simplified circuitry, controlled internal temperatures, and high dust resistance to make it impossible for the device to catch fire. These devices are built so they physically can&#;t trigger combustion when used in an a hazardous environment. As a result, intrinsically safe devices are often lighter weight and less bulky than explosion-proof devices. They can also be more easily maintained without shutting down production.

In contrast, explosion-proof devices don&#;t have to be innately incapable of igniting in a hazardous environment. Instead, explosion-proof devices are housed in an enclosure that can effectively contain an explosion. If the device inside the enclosure does explode, the flames and gases cannot escape and spread to other areas of the facility. These devices are heavier, bulkier, and more time-consuming to install, making them better suited to permanent installations.

How to Choose Intrinsically Safe vs. Explosion Proof Devices

When an electrical appliance is installed in a hazardous area, it&#;s more prone to damage by flammable or combustible gases. And there&#;s a high risk of fires spreading quickly after an initial ignition, which can lead to catastrophic consequences. To minimize these risks, organizations have to use equipment certified as intrinsically safe and/or explosion-proof to prevent combustion and quickly contain fires before they spread.

The type of device you choose (intrinsically safe vs. explosion-proof) will depend on your application&#;s unique requirements. You should work with a certified expert like those at Pruftechnik to determine the best solution for each scenario. However, many facilities find that explosion-proof equipment is best-suited for permanent installations that demand high voltage and power. Meanwhile, intrinsically safe devices might be used for both permanent installations and virtually all portable instrumentation.

What is the Difference Between Flameproof and Explosion Proof? 

Flameproof is another protection technique that leverages enclosures for containment. Flameproof devices are placed into enclosures and sealed shut to keep high pressure from escaping the container and debris from spreading outside the conduits. So, any parts that did ignite would no longer trigger an explosive reaction in the surroundings. 

Flameproof and explosion-proof techniques overlap on the scale of embedded safety, available tools, and underlying process. The key differences between them are found in the specification procedures and testing parameters. Each carries its own regulatory compliance specifications.

Conclusion

Fires and explosions are a risk in many industries, and proper mitigation is key to protecting worker safety, ensuring compliance with the relevant governing bodies, avoiding catastrophic failures, and preventing costly unplanned downtime and operational disruptions. Having the appropriate protective measures &#; including both intrinsically safe and explosion-proof equipment &#; allows engineers and technicians to implement safety controls before accidents can happen.

If you&#;re interested in learning more, speak with one of our specialists. For decades, we&#;ve offered a range of cutting-edge products certified for use in hazardous environments.

Contact us to discuss your requirements of Explosion Proof Junction Box Singapore. Our experienced sales team can help you identify the options that best suit your needs.