Tag: nec

ATEX Rated Cabinet Cooler Systems Now Available From EXAIR!

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In 1815, Sir Humphrey Davy patented an oil lamp for use in coal mines, and coincidentally pioneered the movement to provide safe and reliable products for use in explosion-prone environments. In the days before electricity, miners used lamps that burned fuel oil for lighting. The problem with that was, deposits of underground coal are almost always accompanied by methane gas pockets which, when mixed with coal dust in proximity to an open flame, created terrible and deadly explosions. Davy’s design incorporated a brass net around the wick chamber that let the light out, and let oxygen (necessary for combustion of the fuel oil) in, but if methane entered the wick chamber, it’d extinguish the flame and prevent ignition of the gas outside the lamp.

Industrial growth and the proliferation of electricity that (literally) powered it introduced new hazards in a number of industries other than just mining…which grew exponentially through the 19th century, since coal was the main fuel in electric generating plants. As hazards were identified (usually, unfortunately, by a tragic accident), new and safer products were developed, and eventually, industry professionals implemented controls & standards to make sure these new and safer products were designed, manufactured, and used for the prevention of future tragic accidents.

In North America, the National Electrical Code’s (NEC) system of Classes and Divisions specifies requirements of electrical product testing & use to ensure safety in this regard. In 2014, the European Union created the ATEX Directive, which specifies similar (but not identical) requirements, also aimed at mitigating explosion risks in industrial environments. In 2019, EXAIR introduced our HazLoc Cabinet Cooler Systems, which comply with certain NEC requirements, and we just recently introduced ATEX Cabinet Cooler Systems to comply with that directive.

Both the HazLoc (left) and ATEX Cabinet Cooler Systems are available from stock in NEMA 4 and NEMA 4X ratings.

Like our HazLoc Cabinet Cooler Systems, their ATEX counterparts have been subject to stringent UL testing to ensure compliance with the ATEX Directive. They’re approved for use in areas defined by the Directive as:

  • Zone 2 (an atmosphere where a mixture of air and flammable substances in the form of gas, vapour or mist is not likely to occur in normal operation, but if it does occur, will persist for a short period only) and
  • Zone 22 (an atmosphere where a mixture of air and flammable substances in the form of powder or dust is not likely to occur in normal operation, but if it does occur, will persist for a short period only.)

This fall, EXAIR will celebrate 40 years of dedication to safety and efficiency in engineering & manufacturing compressed air products for a wide range of applications. If you’d like to find out how our Cabinet Cooler Systems – or any of our Intelligent Compressed Air Products – can increase safety and efficiency, and lower sound levels for your compressed air usage, give me a call.

Russ Bowman, CCASS

Application Engineer
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Class I Div 1, Groups A, B, C, and D – Explained

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There are a number of hazards to be considered when using electrical equipment in areas where flammable, combustible, or explosive elements do (or might) exist.  The National Electric Cod (NEC) has a system to delineate areas by Class, Division, and Group, based on the specific nature of the hazard.  There are three Classes, each with two Divisions, and a number of Groups that may apply to each of those Divisions.  Today, we’re going to learn about Class I, Div 1, and the Groups that EXAIR HazLoc Cabinet Cooler Systems are designed for use in.

“Class I” simply means that ignitable concentrations of flammable gases, vapors, or airborne liquids can exist under normal operating conditions.  Examples of such areas include:

  • Refineries
  • Distilleries
  • Fuel storage facilities
  • Spray paint/coating booths

Now, not every single square foot of such areas have ignitable elements in the atmosphere all the time; Class I just means they can have them.  This is where the Divisions come in.

“Div 1” means that these ignitable elements can exist during normal operations, as opposed to “Div 2” which means it’s possible, but not likely.  A good example of the difference here might be a paint booth: inside a paint booth, normal operation is DEFINED as volatile liquid (paint) being discharged into the atmosphere in a spray of fine droplets – hence, that would be Class I, Div 1.  The area adjacent to the paint booth should only have that spray of fine droplets in the air if, say, the exhaust hood of the paint booth failed, or if an operator inadvertently sprayed paint outside the booth, etc…any event or condition that’s possible, but not likely – hence, that would be Div 2.

Not only are hazardous areas classified by Class (nature of the hazardous material,) and Division (likelihood of existence of it,) but they’re further delineated by the type of hazardous material, and these are sorted into Groups.  For Class I (gases, vapors or airborne liquids,) four Groups are applicable.  Materials fall into these groups (with one exception) based on two properties:

  • Maximum Experimental Safe Gap (MESG) – this is a standardized measurement of how easily a gas flame (produced by the ignition of the material) will pass through a narrow gap, bordered by heat-absorbing metal.  
  • Minimum Igniting Current (MIC) ratio, which is the ratio of the minimum electrical current required to ignite the material, by the minimum current required to ignite methane under the same conditions.

Group A is the above mentioned exception.  Because acetylene, of all hazardous materials detailed across the different groups, results in the most violent explosion when ignited, it gets a group all to itself.

Group B is for flammable gases, liquids, and vapors with a MESG less than 0.45mm, and a MIC ratio of 0.40 or less.  Hydrogen, butadiene, ethylene oxide, propylene oxide, and acrolein are popular examples of such materials.

Group C materials have a MESG less than 0.75mm and a MIC ratio less than 0.80 (but greater than 0.40, which would put it in Group B.)  Carbon monoxide, ether, hydrogen sulfide, morphline, cyclopropane, ethyl, isoprene, acetaldhyde and ethylene are some good examples.

Group D consists of all other flammable gases, vapors & liquids with MESG’s over 0.75mm and MIC ratios greater than 0.80.  Gasoline, acetone, ammonia, and benzene are common examples.  Methane is also in Group D, which gives perspective on the materials in the other Groups, which all have a fractionally lower Minimum Igniting Current than methane…the lower the MIC ratio, the lower the current needed for ignition, and therefore, the placement in a more restrictive Group.

EXAIR HazLoc Cabinet Cooler Systems are engineered and approved for use in Class I, Div 1, Groups A, B, C, or D environments.  If you have an electrical panel that needs heat protection in such an area, give me a call.

Russ Bowman
Application Engineer
EXAIR Corporation
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