Explosion-proof electric motor: What you need to know?

What you need to know about the explosion-proof electric motors?

Maintaining the safety and efficiency of your motors is crucial for your facility’s operations. Explosion-proof motors play a vital role in ensuring this safety, especially in hazardous environments. Below, we explore the function of explosion-proof motors, the critical classification considerations, and essential maintenance and repair practices.

Defining an Explosion-proof Electric Motor:

An explosion-proof motor is designed for industrial applications in a highly combustible environment. These motors are built to prevent internal explosions and contain them should one occur due to hazardous environmental factors such as flammable gases, vapors, dust, electrical sparks, and excessive heat.

Explosion-proof motors have a few key features that help them to prevent an internal motor explosion from igniting a larger ambient combustible atmosphere:

uRobust enclosures to contain internal explosions

uTemperature controls to prevent overheating

uTightly sealed components to eliminate ignition risks

uHazardous area certifications ensuring compliance with safety standards

Selecting the Correct Classification:

To ensure optimal safety, an electric motor must be selected for the correct UL classification. These classifications are divided into divisions, classes, and groups based on the type of hazardous environment the motor will be operating in.

Divisions:

The divisions are divided into two classifications, each determined by the conditions of the environment in which the motor will be used.

Division 1– A location that is hazardous even under normal conditions. In other words, when hazardous materials are always present.

Example: Flammable particulate matter or incendiary liquids are produced and accumulate because of the execution of manufacturing processes within your facility.

Division 2 – A location that becomes hazardous in abnormal conditions.

Example: When there is a rupture, burst, or leak resulting in spillage or seepage of flammable substances within the area of your facility.

Classes:

Classes are separated into three hazardous location classifications based on the type of environmental risk each location poses.

Class I: Flammable Gases & Vapors – These locations contain gases & vapors known to auto-ignite and cause explosions.

Gas Examples: Methane, propane, gasoline, acetylene

Location Examples: Oil refineries, chemical plants, and fuel storage facilities.

Class II – Flammable Dust – These locations contain the presence of flammable dust, leading to combustion.

Examples: Dust, grain, coal

Location Examples: Grain mills, coal plants, pharmaceutical facilities

Class III – Flammable Fibers – These locations contain the presence of flammable fibers and filings that may accumulate and lead to a fire.

Fiber Examples: Textile, wood shavings, filings

Location Examples: Textile mills, sawmills, woodworking facilities

Groups:

The groups are created to differentiate between types of flammable agents. These are separated into two separate groups revolving around gases/vapors and particulate matter.

Groups A to D – Acetylene, hydrogen, ethylene, and acetone are a few of the gases and vapors that belong to this group classification.

Groups E to G – Cover materials such as aluminum, coal, corn, and sugar, which fall into this flammable particulate matter classification.

Maintenance & Repair:

In order to ensure the safety of your facility, your explosion-proof motors must be maintained and repaired often.

When an Explosion-Proof motor with a verified UL listing is sent in for repair, the facility may or may not be required to apply a new UL-listed number depending on the nature of the repair. To ensure the motor remains Explosion-Proof, it is crucial that the customer includes the terminal box with the motor. This allows for a thorough inspection of all required surfaces to check for voids or defects.

The inspection process will involve verifying the tolerances of the standard bearing housing and journal dimensions. Additionally, both inboard and outboard seals will be examined to ensure that the clearance between the shaft and the seal remains within acceptable limits. To maintain safety, the motor leads should be encapsulated with a rigid sealing component, such as Chico, to eliminate any internal voids. This precaution helps prevent the risk of ignition in the event of a winding failure that could produce sparks.

Ensuring explosion-proof motors remain in top condition requires specialized knowledge and technical expertise. Southwest Electric Co. is a UL-certified repair facility that specializes in inspecting and maintaining UL-listed motors, including explosion-proof models. Our team is equipped to handle motors weighing up to 100 tons, ensuring high-quality and reliable repairs. Operating 24/7, our skilled craftsmen maintain rigorous technical standards, providing comprehensive documentation for all services performed. Beyond motor repairs, we also service variable frequency drives (VFDs), generators, pumps, gearboxes, hoists, cranes, and other rotating electrical equipment and controls. Our Oklahoma City plant is among the largest motor shop facilities in the country, complemented by our Nashville location offering similar capabilities. We also provide a range of on-location repair services.