Tag: Hazardous Locations

UL Classified Certification for HazLoc Cabinet Coolers

Published on by Russ BowmanLeave a comment

Although history only records back so far, I am certain (based on my experiences with sharp and heavy objects) that humans have been injuring themselves with tools, and the stuff they make with them, since the beginning of time.  In fact, recorded history DOES bear this out…the famous Code of Hammurabi (circa 1750 B.C.) set specific amounts of compensation for specific injuries, as did laws from all over the ancient world, from the empires of Rome to China.  Since then, we’ve come a long way in regulating safety not only for the worker in the workplace, but in public places, homes, and workplaces where manufactured products are used.

UL LLC (or Underwriters Laboratories, as they were known throughout the 20th Century) is a safety consulting & certification company founded in 1894 by an electrical engineer named William Henry Merrill.  A year earlier, an insurance company hired Merrill to perform a risk assessment and investigation of new potential clients…George Westinghouse and Nikola Tesla, the proprietors of the Palace of Electricity at the 1893 Chicago World’s Fair.  It was this experience that made him realize the potential for such an agency to test and set standards for product safety at the dawn of a new age of technology development.  And 120 years on, the benefits in safety & protection have been proven many times over.

If a product or device carries one of these markings, it’s been evaluated for safety by top professionals in the field.

One of the more critical accreditations that a manufacturer can receive for a product is the UL Classified Mark.  This differs from other markings (like the ones shown above for Certified, Listed, or Recognized) in that Classification means that samples of the product were tested & evaluated with respect to certain properties of the product.

EXAIR’s new Hazardous Location Cabinet Cooler Systems bear the UL Classified Mark.  This means they meet the stringent UL requirements for installation on purged electrical enclosures in specific classified areas:

  • Class I Div 1, Groups A, B, C and D
  • Class II Div 1, Groups E, F and G
  • Class III
EXAIR Hazardous Location Cabinet Cooler Systems maintain NEMA 4/4X Integrity and are CE Compliant.

When choosing products for use in classified areas, it’s critical to ensure safety through compliance, and the HazLoc Cabinet Cooler Systems allow you to do that, with simplicity and reliability.  If you’d like to discuss an enclosure cooling application, in or out of a classified area, give me a call.

Russ Bowman
Application Engineer
EXAIR Corporation
Visit us on the Web
Follow me on Twitter
Like us on Facebook

Explanation of Hazardous Locations – Class II Div. 1, Groups E, F and G

Published on by Leave a comment

Per the National Electrical Code (NEC) there are (3) classifications for areas that are defined as hazardous.  They are Class I (gases & vapors), Class II (flammable dusts) & Class III (fibers), the focus of today’s Blog is on Class II locations.

Class II locations are those that are hazardous because of the presence of combustible dust. Note that the dust must be present in sufficient quantities for a fire or explosion hazard to exist. The fact that there is some combustible dust present does not mean a Class II hazardous location exists. Dust is defined as a combustible material that must exist as a finely divided solid of 420 microns (0.420 mm) or less. This will allow the dust to pass through a No. 40 sieve.  Just as in Class I, Division 1 and 2, the subdivision of Class II into Divisions 1 and 2 identifies the likelihood that there is an explosion hazard.

Division 1 locations are defined as an area where the amount of combustible dust is either suspended in the air or accumulated on surfaces in a sufficient concentration to allow for ignition.  The ignition could be caused by a failure or malfunction of the equipment in the classified area.  Group E & F dust (see chart below) are considered conductive and could penetrate into electrical equipment such as electric motors, control panels, electrical panels, etc.. and cause an electrical failure.

Chart1

Group E dusts are metal dusts, such as aluminum and magnesium. In addition to being highly abrasive, and likely to cause overheating of motor bearings if it gets into them. Group E dusts are also electrically conductive and if they are allowed to enter an enclosure can cause an electrical failure.

Chart2

Group F dusts are carbonaceous, the primary dust in this group is coal dust. Coal dust has a lower ignition temperatures than those in Group E.  While Group F dust has a higher thermal insulating value than the layer of Group E.  Therefore Group F requires more control of the temperature on the surfaces that the dust settles on. Group E dusts are semi-conductive, however if the voltages are 600 volts or less it is not generally considered a factor.

Chart3

Group G dusts include plastic dusts, most chemical dusts and food-grain dusts. They are not electrically conductive. Generally these dusts have the highest thermal insulating characteristics and the lowest ignition temperatures. Therefore the equipment used in Group G areas must have the lowest surface temperatures to prevent ignition of a layer.

Chart4

Lastly, equipment rated for use in Classified Environments have a rating called the Temperature Code or “T-Code”.  This is the temperature or temperature range that the rated device will operate normally and/or in a failed or failing state.  Consider something as common as a light fixture, electric motors, etc.. as they could become hot enough to cause ignition depending on the type of dust in the area.  So be sure to check the “T-Codes” for every piece of equipment that will be used within a Classified Environments.

Chart5

When you are looking for expert advice on Hazardous Location Cabinet Coolers or safe, quiet and efficient point of use compressed air products give us a call.   We would enjoy hearing from you.

Steve Harrison
Application Engineer
Send me an email
Find us on the Web 
Follow me on Twitter
Like us on Facebook

Class III Hazardous Areas

Published on by johnball2014Leave a comment

The National Electrical Code, or NEC, classifies hazardous areas into three different categories; Class I, Class II, and Class III.  To use equipment in or around these types of areas, caution has to be taken in order to not cause an explosion or fire.  In the U.S., the Underwriter’s Laboratory, UL, can certify products that can be used safely in these hazardous areas.  EXAIR received our UL Classification for our new product line; the HazLoc Cabinet Cooler Systems.  Under certain guidelines, the HazLoc Cabinet Coolers can be used in Class I for gases and vapors, Class II for flammable dust, and Class III for ignitable fibers and flyings.  In this blog, I will be discussing the Class III classified area.

For a fire or an explosion to occur, we need three things as described in the fire triangle; oxygen, fuel, and an ignition source.  For Class III areas, that fuel is a build-up of material like fabric lint and fine wood shavings.  These small fibers can float and collect on equipment in the surrounding areas.  This collection of material can easily ignite and cause a fire from a spark or a heat source, like kindling.  These fibrous materials and flyings are not explosive, but as a collection, they are a fire hazard; the reason for the Class III designation.  This newest hazardous classification is generally located within the textile and woodworking industries.

The ignition source (the second leg of the fire triangle) is generally from electrical equipment, heat, and static.  Arcs and sparks from motors, contactors, and switches can easily ignite Class III materials; as well as high temperatures from equipment.  NEC and UL segregate this hazardous location into two divisions.  Class III Division 1 is in an area where fibers/flyings are handled, manufactured, or used.  Class III Division 2 is where the fibers/flyings are stored or handled other than in the process of manufacturing.  In both divisions, it is important to protect your electrical systems from these small fibers floating in the surrounding air.

EXAIR's Hazardous Location Cabinet Cooler

The EXAIR HazLoc Cabinet Cooler Systems are designed to keep your electrical panels cool within hazardous areas like Class III because system shutdowns from electrical overheating are costly and potentially dangerous.  If you would like to discuss the details about the EXAIR HazLoc Cabinet Coolers, an Application Engineer at EXAIR will be happy to help you.

 

John Ball
Application Engineer
Email: johnball@exair.com
Twitter: @EXAIR_jb