In the US, industrial safety regulators categorize classified work sites into various groupings: Class I, Class II or Class III. Out of the three classifications, Class I and Class II which involve the presence of flammable gases or vapors and dusts, are considered to be the most common.
Class III Work Site, governing combustible fibers and flyings, is rarely covered because such facilities are not as widespread. However, because Class III locations are equally as dangerous as Class I and Class II sites, it is important to understand the safety standards that govern this grouping.
Class III Work Site Hazards and Definitions
Examples of Class III hazardous locations include the following: textile mills, woodshops and cotton storage centers. Class III equipment, which includes heavy-duty lighting systems and portable tools, are equipped with more or less the same set of features that contain ignitions inside the unit. An exception to this practice is wiring installations for Class III, Division 2 locations.
In most cases, flammable fibers and flyings in Class III facilities are not floating around in the air. Instead, Class III particles tend to build up on immobile machines or permanent structures over time. The accumulation of fibers become extremely dangerous when exposed to an ignition source, such as a spark or intense heat.
Reducing the Accumulation of Heat
It is best practice to maintain adequate ventilation in Class III facilities. This is because fibers or flyings can accumulate on machines, causing heat to become trapped inside the unit. Increasing the operating temperature of equipment can cause malfunction or in the worst-case scenario – result in a fatal explosion, when igniting an unstable, flammable compound.
Class III motors or generators are fully enclosed and have special temperature requirements for certain machines. Open units (without switching features) and squirrel-cage textile motors are examples of machines that can easily exceed Class III temperature standards.
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