Explosion proof motor classification

What is an explosion proof motor?

An explosion proof motor is designed to isolate any explosion originating within its housing and prevent igniting explosive gases or dust in the surrounding atmosphere.  

Why does selecting the right motor matter? The answer lies in ensuring operational safety and adhering to regulatory standards. 

How are hazardous locations classified?

When classifying hazardous locations, a key factor is determining the probability of hazardous materials being present and capable of producing explosions. This assessment is categorized into two primary divisions: 

Division 1: This division is designated for areas where hazardous materials are present during normal operations.  

It means that under regular working conditions, there is a high likelihood that flammable gases, vapors, dust, or fibers are in quantities sufficient to cause an explosion or fire. For example, during normal operation of a processing plant where volatile chemicals are a byproduct of the production process, the area would be classified as Class I, Division 1. 

Division 2: This division applies to locations where the presence of hazardous materials is not likely during normal operation but may exist in case of an accident or unusual operating condition.  

For instance, storage areas where flammable liquids are kept in sealed containers would fall into Class I, Division 2. Hazardous materials are only present if there is an accidental rupture of the container or a system failure. 

Thus, the division system provides a way to gauge the relative risk in different environments and is crucial for selecting the right explosion proof motor. Motors designed for Division 1 locations are constructed to withstand more severe conditions than those for Division 2, due to the greater likelihood of encountering hazardous concentrations of materials. 

After defining the divisions, we then classify these locations into different classes based on the type of hazardous material: 

• Class I locations: Where flammable gases or vapors may be present in sufficient quantities to produce explosive or ignitable mixtures. 
• Class II locations: Where combustible dust may be present in the air and cause a potential hazard. 
• Class III locations: Where there are easily ignitable fibers or materials producing combustible flying. 

Selecting the right explosion proof motor

Choosing the appropriate explosion proof motor or electric motor requires a structured approach, considering the hazardous environment's classification.  

When choosing an explosion proof motor, several factors must be considered: 

• Understand the environment: Assess the division and classification of the location where the motor will operate. Your local authorities may be able to help you with the assessment. 
  • If your location is in Division 1, Class 1: You must use an explosion proof motor for this application.  
  • If your location is in Division 1, Class 2: You can use an explosion proof motor. 
• Know the materials: Identify the groups of inflammable materials present to determine the necessary grade of the motor. 
• Consider usage: Reflect on how the motor will be used and whether it matches the motor's design and capabilities. 
• Check certifications: Ensure that the motor meets the necessary certifications and standards for the industry. 

A comprehensive selection process guarantees a fitting and safe motor for your needs.  

At Hoyer, we can help you find the right motor for your applications. You can explore our range of motors, drives, and controls here.