Electric Motors for Hazardous Locations
Working in environments prone to inflammable gases and liquids, with factors such as high temperatures and sparks can lead to devastating results. Fortunately, there is a line of electric motors that are designed to safeguard such issues by creating complete sealed and hazard free motors. Here, we particularly discuss one of the most well known brands in the market, named as regalbeloit motors.
In essence, electric motors for hazardous locations are named under two main area classification ratings. You may ask what does explosion proof mean?Before answering this question, let’s have look at the environment classifications first;
Division one: These area motors are used for zones with highly hazardous ambient. It means a small sparkle may lead to explosion, electrocution or similar accidents. These motors are built with extra care particularly when explosive conditions are at hand.
Division two: To assume that on the interior of a motor minor sparks can happen, these motors are daybed for rather less hazardous locations, where there is only a potential risk of explosion and hazards are not considered a persistent factor. The structure of the motors is less secured when compared to the previous category. However, division two motors come with Class, Group, and Temperature indicators to choose the best motor for the most suitable ambient.
These class and group categories include Class I and II, and Groups A to G. Let’s have a closer look at these classifications;
Class I Div 1 Electrical Requirements & Group Specifications
This class includes gases, liquids, and vapors that are flammable in nature. It means at the exposure to sparkles and high temperatures, explosions might be inevitable. Class I include the following groups.
- Group A: Any environment with Acetylene or Ethyne hydrocarbons- a volatile gas particularly used in welding gas.
- Group B: Any environment containing gasses such as butadiene, ethylene oxide, hydrogen, propylene oxide: a series of gasses used in both welding and polymer manufacturing.
- Group C: This group includes environments affected by di-ethyl ether, ethylene, or other similar flammable gases.
- Group D: Environments containing acetone, pnictogen hydride, benzene, butane, cyclopropane, ethanol, gasoline, methane, natural gas, naphtha, propane, or other volatile gasses of the simple alkane families.
Any environment exposed to raw material that is combustible in the form of fine powder, also known as combustible dust, is categorized underclass 2 div 2 enclosure;
- Group E: Any atmosphere threatened with aluminum, magnesium and other volatile metal powders come under the Group E.
- Group F: Group F focuses on atmospheres with carbon dust, containing carbon black, coal or any other carbon based material with over 8% volatiles in their chemical compounds.
- Group G: Other combustible dusts that range from edible flours to fine plastic and any other material that is not mentioned in previous groups.
The above categories are considered under North American Motors safety standards. In European committee, the electro technical policies are regarded as Zone One and Zone Two, which are respectively for flammable gas zones and non sparking electric motor necessities.
Choosing an Electric Motor Accordingly
This assessment must be carried out by an expert, and depending on your location, you may require a government registered safety authority to testify the requirements for motors based on hazardous locations, classes, divisions and groups, as well as temperatures in a workplace.
Once the location has been tested, the expert makes a call on whether an explosion proof motor is required at all. If necessary, the electric motor should be under which category. You would probably request any of the following categories;
Severe Duty Motors Category
As the name indicated, these motors are designed for a server environment in terms of potential hazards, with minimal operation demand from the motor. In technical terms, they come under CSA Certified for Class I Division 2.
Industrial use of severe duty motors is seen across the following sectors;
- Paper production and manufactures
- Stone and clay mines
- Food production companies
- Chemical substance manufacturers and distributors
These motors are designed for maximum efficiency and heavy duty use, while enhanced in the long run applications.
IEEE 841 Severe Duty Motors
These categories of motors are specifically designed for oil and gas companies, ranging from refineries, to drilling rigs. The IEEE-841 standard was intended to create electro technical safety policies in and around petroleum plants as well as certain chemical industries dealing with related compounds.
Due to a reinforced safety, corrosion resistance and reliability, these motors have become popular among several other industries including aero, chemical plants, and any other atmosphere dealing with volatile gases.
Here is a general outline of the sectors benefiting from IEEE 841 Severe Duty Motors;
- Oil and gas companies
- Chemical and paint manufacturers
- Mines and mineral refineries
- Flour mills and food processing companies
Each motor is tested under CSA Certified for Class I Division 2 potentially explosive environments.
Explosion Proof Motors
These categories of motors are designed in order to ward off explosions caused by spark and temperature rise. These motors are placed within a completely closed silhouette. Furthermore, Explosion proof motors are safeguarded with a particular construction that can close-in minor explosions, in case a gas or vapor explosion takes place on the inside; this way, it does not start a large explosion in the volatile environment on the outside. These motors are classified under Division One and are means for atmospheres containing gas, vapor and liquid explosives. They are used in the following industrial sectors;
- Petroleum refinery or plants
- Gas and petrol pumps
- Volatile gas and liquid pipelines
- Used as sparkless exhaust fan
Dust Ignition Proof Motors
These motors are completely sealed to preclude minute amounts of volatile material even in the finest dust form, from entering and creating an explosion. These motors prevent overheating, in addition to eliminating volatile factors from coming in contact with explosion starters such as electric flashes, sparks, high temperatures and dynamic ignition. Dust ignition proof motors are categorized as suitable for Division 1 locations.
Industrial utility of these motors mostly revolves around;
- Mill elevators
- Coal mine instrumental
- Feed and cereal equipment
- Pharmaceutical and chemical plants
Cooling Methods for Various Types of Motor Enclosures
To keep matters safe, the electric motors require cooling systems, in addition to a variety of electric motor enclosure types. From this perspective, electric motors are categorized as;
- Drip Proof (DP): they are one of the most exposed motors and are used only in dust free and clean environments and hence made for indoor application.
- Dripproof Force Ventilated (DPFV): this variant of Drip proof motors comes with a ventilating system, structured with openings that prevent liquid and solid materials from entering through- considering the ankle of the drop is not over 15 degrees
- Totally Enclosed Fan Cooled (TEFC) & Totally Enclosed (TEAO): these motors are cooled only through the extraneous surface while the inner side remains untouched.
- Totally Enclosed Non-Ventilated (TENV): self-cooled from the inside by using a hazardous location thermostat, no outer fan or cooling system is involved
- Totally Enclosed Blower Cooled (TEBC): cooled with the help of an external fan.
Our Final Words
Always remember to match the right motor with the work environment. A wrong choice can lead to massive explosions and workplace hazards with life-threatening injuries. A local authority or certified expert can decide whether a motor matches your workplace.
Contact our experts at RAAH International for any questions regarding environmental assessments, if looking for small and large electric motors for sale or to get a quotation on any of these motors.
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