Class III Hazardous Locations Defined

The National Electrical Code (NEC) has a system for classifying areas deemed hazardous due to flammable or combustible materials. When an area is considered classified, extreme caution needs to be taken to ensure nothing within that area provides a possible ignition source. In the US, Underwriter’s Laboratory (UL) provides third-party certification for products that can safely be used in these areas. EXAIR’s newest addition to the longstanding line of Cabinet Coolers was our Hazardous Location Cabinet Cooler. Designed and built with these types of applications in mind, the Hazardous Location Cabinet Cooler has been independently certified by UL for use in Hazardous Locations in Class I Div 1, Groups A, B, C, and D; for use in Class II Div 1, Groups E, F, and G; and also in Class III areas.

Class III areas can often be overlooked as the materials that generally create a Class III area may not always be considered “explosive” by nature. In Class III areas, the risk of combustion occurs due to the presence of ignitable fibers or materials that produce or process combustible flyings. According to the International Electrotechnical Commission (IEC), combustible flyings are defined as solid particles, including fibers, where one dimension is greater than 500µ in size, which can form an explosive mixture with air at standard atmospheric pressure and temperature. These areas are most commonly found within the textile and woodworking industries. The video below, posted to YouTube by News Center Maine, shows just how violent an explosion due to wood fibers can be:

When using a Hazardous Location Cabinet Cooler in a Class III area, it’s important to keep the Cabinet Cooler and immediately surrounding area free of settling debris. Implement a regular inspection, and cleaning procedure if necessary, to ensure that the flyings/textiles don’t accumulate on the Cabinet Cooler.

If you have control panels installed in a hazardous location and are sick of the nonstop maintenance associated with an A/C type system, the Hazardous Location Cabinet Cooler is the right tool for you. Contact an Application Engineer today for help determining the most suitable model for your enclosures.

Tyler Daniel
Application Engineer
E-mail: TylerDaniel@EXAIR.com
Twitter: @EXAIR_TD

Tale Of The Tape: EXAIR Cabinet Cooler Systems vs. Air To Air Coolers

As summer heat continues to rise, so does the volume of inquiries we get for EXAIR Cabinet Cooler Systems.  Many callers want to know what differences they can expect in using our products versus other methods they’re considering…or even using…right now.

One very common method is the use of a fan to draw cooling air into the panel, from the surrounding environment.  This is the simplest, and least expensive option, but it has two main drawbacks:

  • Components inside the panel are now exposed (albeit in a controlled manner) to the very same environmental elements that putting them inside a panel was supposed to protect them from.
  • Since the air surrounding the panel is the cooling medium, the temperature inside the panel will never be lower than the temperature outside the panel.  Fan cooling in hot environments will still allow overheating.
If a computer’s fan in the family room can get this dusty, imagine how much worse a control panel on a factory floor can get.

Two key benefits of EXAIR Cabinet Cooler Systems take direct aim at these drawbacks:

  • Once properly installed on a sealed enclosure, all the air entering the enclosure comes from your compressed air supply.  It’s also been through the Automatic Drain Filter Separator that comes with every EXAIR Cabinet Cooler System, so it’s clean and moisture free.
  • The air generated by the Cabinet Cooler is refrigerated, thanks to the Vortex Tube phenomenon.  It doesn’t matter how hot it is in the area; the air going into the panel is about 50F colder than the compressed air supply.  
Cold air from your compressed air supply, with no openings to the environment, eliminates any environmental effects on cooling capabilities.

Fans are one of the two methods of “air to air” cooling – the other is a closed loop system commonly known as a heat pipe:

*Hot air (inside the panel) causes refrigerant in heat pipe to flash to a gas.
*Cold air (from the environment) causes the refrigerant to condense to a liquid.

While this eliminates the environmental contamination concerns of dirt & humidity, it’s still limited.  Just like fan cooling, this method cannot make it cooler inside the enclosure than the ambient temperature in the surrounding area.

Despite this limitation, heat pipes (first column, below) are generally quite cost effective.  But, considering a total cost of ownership difference of less than $15/year, it’s clear that EXAIR Cabinet Cooler Systems, which aren’t limited by ambient temperature, are a strong contender for favorite selection.

Reliable, durable, and cost effective: the EXAIR Cabinet Cooler System.

EXAIR Cabinet Cooler Systems provide up to 5,600 Btu/hr worth of cooling power.  Regardless of your environment (even Classified/Hazardous locations,) we’ve got a system to keep your electronic and electrical panels safe from heat, humidity, and contamination. If you’d like to discuss enclosure cooling and the benefits of EXAIR Cabinet Cooler Systems, give me a call.

Russ Bowman
Application Engineer
EXAIR Corporation
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Computer Fan image courtesy of tico_24 Creative Commons License

Class II Hazardous Areas, Groups E, F and G Explained

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 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 HazLoc Cabinet Cooler® Systems.  Under certain guidelines, the HazLoc Cabinet Coolers can be used in Class I areas for gases and vapors, Class II areas for flammable dust, and Class III areas for ignitable fibers and flyings.  In this blog, I will cover the Class II hazardous areas.

First, HazLoc Cabinet Coolers are designed to keep electrical components cool during summer months and higher ambient conditions.  They are powered by an EXAIR Vortex Tube which only uses compressed air to generate cold air.  They do not have any moving parts, refrigerant, or refrigerant compressors to fail.  These simple, but effective, cooling devices can be used in the toughest of environments.  With the Vortex Tube as the “engine”, the reliability of the EXAIR HazLoc Cabinet Cooler is unmatched.  It is an easy choice for cooling electrical panels and reduce premature shutdowns.

For a fire to occur, we only need three things as described by the fire triangle; oxygen, fuel, and an ignition source.  For an explosion, we need two other conditions, dust concentration and confinement.  For a Class II area, the fuel is combustible dusts.  “Combustible dusts are fine particles that present an explosion hazard when suspended in air under certain conditions.”1  By NEC standards, dust is categorized into three different groups.  Group E is for metal dust.  This will include aluminum and magnesium dust.   Group F is for carbonaceous dust like charcoal, coal, and carbon black.  And Group G is for non-conductive dust like flour, grain, and plastic.  These fine particles can float and collect on equipment in the surrounding areas.  This collection of material can ignite and cause a fire from a spark or a heat source.  If they are contained like within a panel, then there is a possibility of an explosion.

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

The EXAIR HazLoc Cabinet Cooler Systems are designed to keep your electrical panels cool within hazardous areas like Class II above.  Because system shutdowns from electrical components overheating are costly and potentially dangerous, you can install a HazLoc Cabinet Cooler System without sacrificing your panel’s integrity.  If you would like to discuss in more detail about the different types of 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

 

Note 1: Osha.gov publication

Photo: Inflammable Sign Hazardous Symbol European by Clker-Free-Vector-Images.  Pixabay License

What Are NEMA Types And Why Do They Matter for Your Enclosure?

NEMA Type 4X Dual Cabinet Cooler System in 316 Stainless Steel

Electrical enclosures and control cabinets come in all shapes, sizes and colors. They all have the same job, to protect and house critical electronics in order to ensure a machine or piece of equipment can safely operate.  These electronics and enclosures are also located in a variety of environments that differ just as much as the panels themselves.  With that, different requirements and needs to protect the internal components of the cabinet are needed.  A systematic approach to designate the requirements for these panels to meet the needs of different environments was designated by the National Electrical Manufacturers Association.  Thus, the NEMA rating was created.

Currently, there are nearly 20 different NEMA classifications that enclosures can be designed for and operate within. EXAIR offers three main NEMA types which are the most commonly found within industrial facilities as well as an additional two that are designated strictly for Hazardous Locations and are separately certified by UL to meet those standards.

NEMA Type 12 Cabinet Cooler System protects an HMI on a machine tool.

NEMA Type 12 enclosures are constructed mainly to be used indoors and to protect personnel in the area from any hazardous equipment such as electrical contacts or transformers. This also helps to protect those electronics from things like foreign matter in the air around the panel and keep any kind of drips of moisture from getting into the electronics. These are found in most general light assembly or industrial environments.

EXAIR NEMA Type 4 Cabinet Cooler System protects against direct water.

NEMA Type 4 enclosures are a few steps up from NEMA Type 12 in the level of protection they give the internal electronics. These are suitable for indoor or outdoor use to protect both personnel and the internal cabinet components from the environment.  They are dust and airtight as well as protect from the ingress of water and ice. These can be found in washdown environments, hot environments, or extremely dirty environments throughout industry.

EXAIR NEMA 4X Cabinet Cooler Systems are made of corrosion-resistant stainless steel for corrosive environments and are also available with Side Mount Kits.

NEMA Type 4X enclosures are similar to NEMA Type 4 as far as that they protect for and the environments they are suited for, the standard also adds a level of corrosion resistance to the panels which permit them for use around certain chemicals and/or outdoors in certain facility environments.

Hazardous Location Cabinet Cooler Systems

The last type to be discussed is the Hazardous Locations that are offered in both NEMA Type 4 and NEMA Type 4X ratings.  These environments are under strict classifications and EXAIR follows the UL Classified certifications for these restricted areas.

If the panel or environment within a given facility is in a different NEMA type than the ones mentioned above it can often be remedied by going to the next highest level.  For instance, NEMA Type 5 rated enclosures could be protected by a NEMA Type 4 and still maintain their integrity.

If you would like to discuss NEMA ratings or what type of panel may be within your facility, please contact us.

Brian Farno
Application Engineer
BrianFarno@EXAIR.com
@EXAIR_BF