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