Pepperl + Fuchs have brought out a simple and effective presentation of explosion protection and intrinsic safety. Their presentation summarizes the following:
- "A hazardous location is an area in which the atmosphere is explosive or anticipated to be explosive
- Intrinsic safety dates back to 1913 following a disastrous mine explosion in England
- The Ignition Triangle consists of three components (fuel, ignition energy and oxidizer) that must be present simultaneously, and in suitable proportions, to cause an explosion.
- Minimum Ignition Energy (MIE) is the ideal ratio of fuel to air where the mixture is most easily ignited
Any area above or below the Minimum Ignition Energy contains a smaller fraction of air or combustible gas/fuel and cannot be ignited - Hazardous areas in North America are broken down into three classifications: Class I (flammable gases or liquids), Class II (dust), and Class III (fibers and flyings)
- The classifications are further broken down in Division 1 or Division 2 based on the probability of the materials being present in a potentially hazardous quantity
- The Division Method of North America is comparable to the Three-Zone Model practiced in Europe
- There are three basic methods of explosion protection: containment, segregation, and prevention
- Intrinsic safety is the principle of keeping the electrical energy below the MIE and is the preferred method of explosion protection for low power devices"
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