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.
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.
A factory was having some issues in losing plastic material underneath and around their conveyor system. The conveyor moved plastic fibers from an extrusion process into a hopper. The conveyor belt was made of a rubber material that was 17” wide, and the plastic fiber was made from HDPE. As the conveyor went around the end to dump the fibers into the hopper, some of it would stick to belt and sides of the conveying system. Some fiber material would fall onto the ground which would require cleaning and loss of material. They attempted to place a brush flap against the conveyor belt to knock the material off, but it was not very effective. The brush flap actually generated more static as well as created wear marks on the belt from contact. The customer sent a picture of the problem and wondered if EXAIR could help them with this application.
With plastic fibrous material and rubber belts, the two non-conductive surfaces will generate static. Static can have a strong force that will cause the material to “stick” to surfaces. The higher the static voltage, the stronger the force. As you can see in the photo, the material is sticking to the belt as well as to the sides. For this application, I recommended the model 112224 Gen4 Super Ion Air Knife Kit. The Gen4 Super Ion Air Knife is uniquely designed to have two functions in this application. The Super Ion Air Knife uses 40 parts of ambient air with every one part of compressed air, making it very efficient. With the laminar air stream that comes from the Super Air Knife, it can carry both positive and negative ions from the attached Gen4 Ionizing Bar to remove any type of static charge. With this combination, it becomes a very effective non-contact scraper to remove the fibers and not wear on the conveyor belt. The model 112224 kit includes the 24” (610 mm) long Super Air Knife with a Gen4 Ionizing Bar attached; power supply, filter, regulator, and a shim set.
The reason for the 24” (610 mm) extended length was to keep the fibers from collecting to the outside area of the conveyor (as shown in the photo above). With the compact and lightweight design, it could easily be positioned below the conveyor. As the fiber material would come around the conveyor, the ions carried by the air stream would neutralize the static as well as remove the material from the belt and the sides. When the customer mounted the Gen4 Super Ion Air Knife in place, the plastic fibers dropped into the hopper and not onto the floor underneath.
Spillage is wasteful, costly, and time consuming to cleanup. If you have excess waste from your conveying system, EXAIR will have the product to help you. For the customer above, the Gen4 Super Ion Air Knife made it possible to claim more material, removed the hazard from buildup on the floor, and reduced cleaning time. You can contact an Application Engineer to review your application.