Killark Full Line Catalog

KILLARK INTRODUCTION

HAZARDOUS LOCATION DATA

intended use and must carry markings to identify that. In Class I, Division 2 locations, certain “non-hazardous” types of equipment, such as terminals and non-sparking motors, are permitted. Equipment specifically built for Class I locations will be marked to indicate where the equipment can be installed. This is discussed in greater detail below. Class II, Division 1 areas the primary protection method are dustproof or dust ignition-proof. In many cases, equipment which is suitable for use in Class I locations is acceptable in Class II locations however, it must be specifically marked as such. For Class III locations the determining factor is more preventing accumulations inside equipment and temperature control. Zone Approved Equipment The Zone system identifies Equipment protection levels (EPL) which assign a code defining the level of protection of equipment that is based on the likelihood of the equipment becoming a source of ignition. The EPL uses “G” for Explosive Gas Atmospheres and “D” for Explosive Dust Atmospheres. This is followed by one of the three levels of protection with “a” being the highest and “c” the lowest which translate into suitability for the various Zones or Divisions. The IEC also identifies Explosive Atmospheres in mines susceptible to firedamp which is not part of the NEC or CEC. • EPL Ga — equipment for Explosive gas Atmospheres, having a “very high” level of protection, which is not a source of ignition in normal operation, during expected malfunctions or during rare malfunctions • EPL Gb — equipment for Explosive gas Atmospheres, having a “high” level of protection, which is not a source of ignition in normal operation or during expected malfunctions • EPL Gc — equipment for Explosive gas Atmospheres, having an “enhanced” level of protection, which is not a source of ignition in normal operation and which may have some additional protection to ensure that it remains inactive as an ignition source in the case of regular expected occurrences (for example failure of a lamp) • EPL Da — equipment for Explosive dust Atmospheres, having a “very high” level of protection, which is not a source of ignition in normal operation, during expected malfunctions, or during rare malfunctions • EPL Db — equipment for Explosive dust Atmospheres, having a “high” level of protection, which is not a source of ignition

in normal operation or during expected malfunctions • EPL Dc — equipment for Explosive dust Atmospheres, having an “enhanced” level of protection, which is not a source of ignition in normal operation and which may have some additional protection to ensure that it remains inactive as an ignition source in the case of regular expected occurrences (for example failure of a lamp) EPL G a Protection Level a – Highest (Zone 0, 20) b – High (Zone 1, 21) c – Enhanced (Zone 2, 22) Material EQUIPMENT PROTECTION LEVEL EPL ZONE SUITABILITY DIVISION SUITABILITY Ga Zone 0 Class I, Division 1 Gb Zone 1 Class I, Division 2 Gc Zone 2 Class I, Division 2 Da Zone 20 Class II/III, Division 1 Db Zone 21 Class II/III, Division 2 Dc Zone 22 Class II/III, Division 2 Both the NEC and CEC refer to newer versions of the IEC 60079 Series of Standards. Many of these have been rewritten to include multiple levels of protection. Originally, with the exception of Intrinsic Safety which had 2 levels of protection (“ia” for Zone 0, and “ib” for Zone 1) all other standards had a single level of protection (later Encapsulation “Ex ma” “Ex mb” were added). All Zone 2 requirements were contained in IEC 60079-15 (UL/ISA/ ANSI and CSA adopted these standards). To address the specific technical requirements of Zone 2, Explosive Dust Atmospheres and to allow for other equipment to be allowed in Zone 0, changes to the IEC standards are underway to add “Levels of Protection” to each “Types of Protection”. Many of these are recognized in the NEC and CEC. The Levels of Protection follow the EPL in that “a” is the highest protection and “c” is the lowest. G – Explosive Gas Atmosphere D – Explosive Dust Atmosphere Equipment Protection level

BASIC TYPES OF PROTECTION OF EQUIPMENT FOR HAZARDOUS LOCATIONS EXPLOSION PROOF (TYPE OF PROTECTION “Ex d” FLAMEPROOF) (Also “Ex da” (for gas detection only), “Ex db” and “Ex dc”) The basic protection concept of Explosionproof and Flameproof are the same although certification requirements for flameproof are less severe than those for explosionproof equipment. The intent of both is to contain an internal explosion of gas or vapor and prevent the escape of any hot or burning materials that could ignite the surrounding atmosphere. Because “Flameproof equipment” is not permitted to be used in Zone 0 Locations this type of construction cannot be used permitted in Class I, Division 1 locations (which theoretically includes Zone 0). Since flammable gases and vapors are expected to be inside the enclosure the equipment design must be capable of withstanding an explosion caused by sparks from contactors or other switching devices, high temperatures, or electrical faults. The enclosure is designed so that hot gases generated during an internal explosion are cooled below the ignition temperature of the surrounding flammable atmosphere as they are transmitted through the joints of the enclosure. In addition, the external surfaces of enclosures must reach temperatures that could ignite a surrounding atmosphere as a result of heat energy within the enclosure. This heat energy may be the result of normal operation of heat producing equipment such as lighting fixtures, or the result of an electrical arc to the enclosure from an arcing ground fault. Explosionproof and Flameproof use various types of joints to maintain their protection. • Threaded Joints used for conduit entries or enclosure covers. • Flat Joints between mating surfaces that are bolted tightly together, • Cylindrical Joints such as used in push buttons, toggle switches, and shafts for electric motors • Rabbet Joints commonly used for large diameter cylindrical parts, such as between a motor end bell and the main frame. • Labyrinth Joints is used on both rectangular and cylindrical parts which force expanding hot gases to make several right-angle turns before they can exit an enclosure

Original Marking

Ex e

Type of Protection

New Marking

Ex e b

Level of Protection Type of Protection

H8

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