Hazardous Location Motors

NEMA (National Electrical Manufacturers Association) classifications play a critical role in defining the safety and performance standards for motors used in hazardous locations. These classifications specify the level of protection that motor enclosures must provide against potentially explosive atmospheres, dust, and other environmental hazards. By categorizing enclosures according to their ability to withstand specific conditions, NEMA ensures that hazardous location motors operate safely and effectively in challenging environments. Understanding these classifications is essential for selecting the right motor for your application, ensuring compliance with safety regulations, and minimizing the risk of accidents in hazardous areas.

There are three main categories of classification:

1. Division
2. Class
3. Group

Division: This category defines the likelihood of a hazardous substance being present in an area. There are two types of divisions:

• Division 1: A hazardous substance is likely to be present under normal operating conditions.
• Division 2: A hazardous substance is only likely to be present under abnormal conditions, such as equipment failures or other unusual circumstances.

Local safety authorities determine what constitutes normal and abnormal conditions. Therefore, the first step in classification is to consult with local authorities to identify whether a specific location falls under Division 1 or Division 2.

Class: This category defines the type of hazard present in the environment. There are three different classes:

• Class I: Involves chemical gases or vapors, such as gasoline or acetylene, which are present in the environment.
• Class II: Involves flammable dust, such as coke dust or grain dust, in the environment.
• Class III: Involves flammable lint or fibers, such as those found in textile production or sawdust, in the area.

Groups: This category identifies the specific chemical gas, vapor, or dust present in the environment. The term “group” refers to the classification of different atmospheric mixtures based on their hazardous characteristics.

• Groups A, B, C, and D: These groups consist of gases or vapors and are relevant only under the Class I category.
• Groups E, F, and G: These groups consist of dust and are relevant only under the Class II category.

These electric motors are constructed to the requirements of U.L. Class I, Group C & D, Division 1. They are then modified to accept purge fittings on the motor and terminal box. In addition to the purge fittings the motor is also supplied with a Pepperl+Fuchs “Type X” purging system. This can be mounted on the motor, or wall mounted within 5 feet of the motor. The size of the motor is limited by the area to be purged.

The Pepperl+Fuchs “Type X” pressurization or purging system operates using a supply of compressed instrument air or inert gas. Its purpose is to regulate and monitor the pressure within the motor and terminal box, effectively removing and preventing the accumulation of flammable vapors or gases. In Class I areas, the system is designed to perform ten air exchanges and maintain a safe internal pressure of 0.25 inches inside the motor enclosure. The system also includes an Electrical Power Control Unit (EPCU), which monitors the operation of the system and controls the motor’s power. The EPCU ensures that all start-up requirements are met before allowing power to the motor. This process reduces the Hazardous (Classified) Area Rating within the motor and terminal box in accordance with NEC – NFPA 70, Article 500, NFPA 496, and ISA DS12.4.

Class I, Division 2 motors are designed for use in environments where hazardous substances, such as flammable gases or vapors, are not typically present under normal operating conditions but may become present under abnormal circumstances, such as equipment failure or accidental release.

These motors are built to withstand and operate safely in such environments by minimizing the risk of ignition in the presence of flammable substances. Unlike Division 1 motors, which are designed for continuous exposure to hazardous conditions, Division 2 motors are constructed to ensure safety if a hazardous atmosphere briefly develops.

In these motors, components are typically enclosed to prevent sparks or high temperatures from igniting surrounding gases or vapors. They may also incorporate features like non-sparking parts or sealed enclosures to further reduce the risk of ignition. The design and construction of Class I, Division 2 motors adhere to stringent safety standards, ensuring that they meet regulatory requirements for use in potentially hazardous environments.

Overall, Class I, Division 2 motors are crucial for maintaining safety in environments where the presence of hazardous substances is infrequent but possible, ensuring that operations can continue without risking explosions or other dangerous incidents.

What Are Purged Hazardous Location Motors and Why You Need Them

Purged hazardous location motors are specialized electric motors designed for use in environments where flammable gases, vapors, or dusts may be present, creating a risk of explosion. These motors are specifically constructed to meet the rigorous safety standards required for operation in Class I, Group A and B, Division 1 hazardous locations, where the presence of explosive atmospheres is a significant concern.

How Purged Motors Work

The base hazardous location motors are built to U.L. Class I, Group C & D, Division 1 standards and then modified to include purge fittings on both the motor and terminal box. This modification is what allows these motors to be used in the more hazardous Group A and B environments.

The purging process involves the use of a Pepperl+Fuchs “Type X” purging system, which can either be mounted directly on the motor or within 5 feet of it. This system uses a supply of compressed instrument air or inert gas to purge the motor enclosure, removing any flammable vapors or gases and preventing their accumulation. By maintaining a positive pressure inside the motor enclosure, the system ensures that hazardous substances cannot enter, thereby reducing the risk of ignition.

Why You Need Purged Motors

In environments classified as Class I, Division 1, the risk of encountering explosive gases or vapors is high, and any spark or high temperature within a motor could lead to a catastrophic event. Standard motors are not designed to handle such conditions, which is why purged motors are essential. The Pepperl+Fuchs “Type X” purging system is engineered to perform multiple air exchanges and maintain a consistent pressure of 0.25 inches inside the motor enclosure, ensuring that the environment within the motor remains safe even in the most hazardous conditions.

Additionally, the system includes an Electrical Power Control Unit (EPCU) that monitors the purging process and controls the motor’s power. The EPCU ensures that the motor only receives power once all safety criteria are met, and it will automatically shut down the motor if the safe pressure is lost. This layered safety approach significantly reduces the Hazardous (Classified) Area Rating within the motor and terminal box, in compliance with NEC – NFPA 70, Article 500, NFPA 496, and ISA 12.4 standards.

Applications and Certification

Purged motors are indispensable in industries where safety is paramount, such as chemical processing, oil and gas, and other sectors where explosive atmospheres are a constant threat. The Pepperl+Fuchs Type X purging system, which is certified for Class I, Groups A, B, C, D, and Class II, Groups E, F, G, Division 1, meets all necessary safety standards, including ATEX, NFPA 496, and IEC Ex.

While U.L. and CSA do not certify motors for Class I, Groups A and B, Division 1 locations, purged motors offer a viable solution by reducing the internal classification from a hazardous area to a non-hazardous one. This allows general-purpose equipment to operate safely within the protected enclosure.

Zone 1 Motors

Zone 1 Motors are designed for environments where hazardous substances, such as flammable gases, vapors, or mists, are likely to be present during normal operations. Classified under both ATEX and IECEx standards, Zone 1 is a designation that indicates a higher risk area where the potential for an explosive atmosphere exists regularly or intermittently. Motors used in Zone 1 must be constructed to prevent ignition and withstand the rigors of operating in these volatile environments. They are typically built with enhanced safety features, such as flameproof enclosures or pressurization systems, to ensure that any sparks, hot surfaces, or electrical arcs are contained, reducing the risk of ignition. These motors are essential in industries like oil and gas, chemical processing, and any other sectors where hazardous atmospheres are a regular part of the working environment.

Zone 2 Motors

Zone 2 Motors are designed for environments where hazardous substances, such as flammable gases, vapors, or mists, are not typically present during normal operations but could appear under abnormal conditions, such as in the event of a leak or equipment failure. Classified under both ATEX and IECEx standards, Zone 2 indicates a lower risk area compared to Zone 1, where the presence of an explosive atmosphere is infrequent and short-lived. Motors used in Zone 2 must be capable of operating safely without igniting any hazardous substances that might briefly be present. These motors often feature non-sparking components, increased safety designs, or other protective measures that minimize the risk of ignition. They are commonly used in industries like petrochemicals, pharmaceuticals, and manufacturing, where the likelihood of encountering a hazardous atmosphere is low, but safety cannot be compromised.