When it comes to electrical equipment, and in our case electrical cabinets, there are regulations we all must follow for safety concerns from hazardous locations. There are explosion hazards that occur when handling flammable gases, vapors and dust. Hazardous location regulations have been designated from the NEC, CEC, OSHA and the NFPA. There is also a Globally Harmonized System (GHE) that oversees labeling the hazards of products.

In the US the governing body for electrical hazards is the NEC (National Electric Code). In Canada, it is the CEC (Canadian Electric Code). These 2 agencies work very closely together in North America, and have very few differences – the main differences concern how and where signs are posted, not the hazards themselves. Both agencies utilize document NFPA 70 (National Fire Protection Agency) as the primary basis for all electrical hazard information and requirements. The NFPA 70 outlines the different Classes and Divisions.

As we look at our Class II Div 1 groups E,F, and G Cabinet Cooler Systems, where can we actually use them? First, they are to be used in conjunction with a purged and pressurized control, system. They are not a replacement of such systems but, rather, provide cooling for them. To fully understand the environments they can be used, we need to understand the class, division and group meanings so let’s dive in…

Let’s jump right into a brief overview of the Classifications. The classifications offer a precise description of the hazardous material that is (or most likely) in an area, so that the appropriate equipment can be used, and safe installations can occur. Sometimes these classifications are easily recognized, and many times they may take a detailed study of the site. There are 3 categories of hazardous materials which define the type of explosive (or flammable) that is present:

Class I = Flammable vapors, gases or liquids – examples would be areas such as Gasoline storage, petroleum Refineries, Dry Cleaning Plants, Fuel Servicing Areas, Spray Finishing areas, etc…

Class II = Combustible dust – examples would be Grain elevators, Flour and feed mills, Metal powders manufacturers, coal plants, etc…

Class III = Ignitable Fibers and flyings – Examples would include sawdust areas, Textile mills, Cotton processing, Cotton Seed Mills, etc..

Now as we dissect this further, we will see that each of these “Classes” are divided into 2 divisions. We many times hear these expressed as Div1 and Div 2. The Divisions tells of the likelihood that a hazardous material may be present in a flammable concentration.

Division 1 = an area where the explosive or flammable vapors, gases, dust, fibers, or liquids (as mentioned in Class definitions) can exist under normal everyday operating conditions.

Division 2 = an area in which the dangerous vapors, gases, dust, fibers, or liquids are NOT likely to be present under normal operations.

After the Classes and the Divisions come the groups.

Class 1 has 4 groups, A-D. These are all gases.

Group A = Acetylene is in the air

Group B = Flammable gases with a Minimum Igniting Current (MIC) less than 0.40 such as hydrogen, butadiene, ethylene oxide, propylene oxide

Group C = Flammable gases with a Minimum Igniting Current (MIC) greater than 0.40 such as ethyl ether, ethylene, acetaldehyde, and cyclopropane

Group D = Flammable gases with a Minimum Igniting Current (MIC) greater than 0.80 such as acetone, ammonia, benzene, butane, ethanol, gasoline, methane, natural gas, naphtha, and propane.

Class II has 3 groups, E,F and G. These are all types of dust

Group E = Combustible Conductive metal dust such as aluminum and magnesium

Group F = Combustible electrically Non-Conductive dust such as coal, carbon, charcoal

Group G = Combustible dusts not included in E or F such as flour, grain, wood, plastic and chemicals.

As we come full circle here looking at our Class II, Div 1, Groups E,F, and G Cabinet Cooler systems, we now understand the following:

• We know that these systems are perfect for areas that contain combustible dust such as coal dust, flour, grain and feed (Class II)
• We also know that these will work well in areas where these combustible dusts are constantly present around this Cabinet Cooler (Div 1)
• Lastly we understand that these are a great fit for all types of dusts, whether conductive or not (Groups E,F,G)

Please feel free to reach out to myself or any of the application engineers for further questions on this or any of our amazing products.

Thank you for stopping by,

Brian Wages

Application Engineer

EXAIR Corporation
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Cover photo by Clker-free-vector-images/29545, licensed by Pixabay