Intrinsically Safe Definitions and Standards

Posted by Bob Russell On August - 4 - 2009

We introduced the topic of Intrinsic Safety yesterday in our August 3 post.  In that post, I promised to cover the Intrinsically Safe definitions and standards today. 

Non-incendive Devices, Circuits, and Components: incapable of generating thermal or electrical energy sufficient to ignite a volatile atmosphere under normal operating conditions-although sufficient energy for ignition could be generated under fault Sparkconditions.  A Non-Incendive device is designed for use in environments where the specified hazard may be present, but is not likely to exist under normal operating conditions.

Class I is part of the National Electric Code definitions of hazardous location classifications and protection techniques. The Class I classification is a segment of the basic designation which is listed by “class” and “division”.
 
Class I locations are areas where flammable gases may be present in sufficient quantities to produce explosive or flammable mixtures. Class II locations can be described as hazardous because of the presence of combustible dust. Class III locations contain easily ignitable fibers and flyings. Division 1 designates an environment where flammable gases, vapors, liquids, combustible dusts or ignitable fibers and flyings are likely to exist under normal operating conditions. On the other hand, Division 2 is an environment where flammable gases, vapors, liquids, combustible dusts or ignitable fibers and flyings are not likely to exist under normal operating conditions. Hazardous atmospheres are further defined by “groups.”

Intrinsically Safe (I-Safe) Devices, Circuits, and Components: are incapable of generating thermal or electrical energy sufficient to ignite a volatile atmosphere under either normal or abnormal operating conditions. Consequently, intrinsically safe systems have much wider application than their non-incendive counterparts. Non-incendive systems are generally less costly and easier to maintain than either explosion-proof or intrinsically safe systems.

Class 1, Division 2 Safe Device: Device which is safe to operate in locations (1) in which volatile flammable liquids or gases are handled, processed or used but which are normally confined in enclosed containers or systems, (2) in which ignitable concentrations of gases or vapors are normally prevented by ventilation, (3) which are adjacent to Class I Division I locations and not separated by a vapor tight barrier.  An intrinsically safe device is approved for use in the specified class and division and will not produce any spark or thermal effects that will ignite a specified gas mixture.

ATEX: Derived from the French “ATmosphere EXplosible” (explosive atmosphere). Refers to Atex Directive 04/9/EC, the European regulation governing equipment and protective systems intended for use in potentially explosive atmospheres.

 Contact DecisionPoint Systems, Inc. to learn more about non-incendive and Intrinsically Safe (I-Safe) mobile devices and what you need to protect your employees. 

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