The UL Classified Mark

Safety, it’s a word that gets tossed around in both the work place and in your daily life.  From the beginning of time, people have been injuring themselves at work and at home. Today’s well known phrases “Hey watch this” or “Hold my Beer” became a popular way to say I am about to do something crazy and stupid and I know it. As someone who enjoys the outdoors and the thrills of extreme sports, I can attest from both personal experience and the experiences of those around me that people don’t make smart decisions. At a young age I had a laundry list of injuries longer than most people 10 years older than me. But even in the craziest of my stunts (i.e. running an 18’ waterfall in a kayak) there is a level of safety that is put into place. That safety can come from the practice it takes to develop higher skill (experience) or from the knowledge of experts around you. 

Companies have been trying to figure out ways to make offices and manufacturing plants a zero-incident environment for a long time. A lot of safety departments call this journey the Road to Zero and track each incident closely. Aside from policies and equipment modifications there are consulting and certification companies that focus solely on the safety of products used in manufacturing and production plants. One of the more prominent companies in the U.S. is UL or Underwriters Laboratories; this company was founded by an electrical engineer named William Henry Merrill in 1894. In 1893 an insurance company hired Merrill to perform a risk assessment on new potential clients, George Westinghouse and Nikola Tesla. This led him to realize the potential for an agency to test and set standards for product safety.

One example of a sought after and critical accreditation is the UL Classified Mark. The UL Classified certification means that the product has been evaluated, tested and passed the test for being safe when installed within classified areas. This includes a large range of hazardous locations which according to OSHA is defined as an explosive atmosphere due to the presence of flammable fluids (Class 1), combustible dusts (Class 2), or ignitable fibers and flyings (Class 3). These areas include everything from chemical plants to the food industry.

EXAIR’s Hazardous Location Cabinet Cooler

EXAIR has a Cabinet Cooler that can be used in these Hazardous Locations and earned the UL Classified Mark. The Hazardous Location Cabinet Cooler Systems are designed to be used with purged and pressurized systems in the following locations:

Class I Div 1, Groups A, B, C, and D
Class II Div 1, Groups E, F, and G
Class III

This means that the Hazardous Location Cabinet Coolers can be used in areas with explosive gas and vapors, combustible dusts, or ignitable fibers. 

If you have any questions about compressed air systems or want more information on any of EXAIR’s products, give us a call, we have a team of Application Engineers ready to answer your questions and recommend a solution for your applications.

Cody Biehle
Application Engineer
EXAIR Corporation
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Class I Div 1, Groups A, B, C, and D – Explained

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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