Allied Tube & Conduit 140 atkore.com/flexicon Flexicon Introduction Hazardous Areas exist where a flammablemixture of gas and air, or dust and air, can exist in large enough quantities and for long enough periods to create a risk of explosion if an ignition source is present. Wherever possible it is important tominimise the risk of explosive mixtures forming and / or the risk of ignition. In the instances where this is impossible or impractical then means of providing a level of protection are required. This guide will briefly explain how people and plant can be protected in hazardous areas. The guide is particularly focussed towards applications for the Flexicon EXD conduit gland and is not intended to be a full guide to hazardous areas. Users of this conduit gland should be fully qualified, competent and conversant with hazardous area requirements. Flammable Mixtures & Ignition Sources Flammable gases when mixed with air can be explosive. Gases are categorised into 3 groups with Group A being the least explosive and Group C being the most explosive. Equipment is also classified from T1 to T6 according tomaximum allowed temperature of the equipment to prevent ignition of the gas/ air mixture it is designed to work in. Certain fine dusts dispersed in air can also be explosive. Ignition sources include: sparking due to static discharge, electrical arcs, lightning, hot engine exhaust, hot equipment and heat from chemical reactions. Hazardous Area Zones The level of risk in hazardous areas is defined by a zoning system. Zone 0 A place in which an explosive atmosphere consisting of a mixture with air of dangerous substances in the formof gas, vapour or mist is present continuously or for long periods or frequently. Zone 1 A place in which an explosive atmosphere consisting of a mixture with air of dangerous substances in the formof gas, vapour or mist is likely to occur in normal operation occasionally. Zone 2 A place in which an explosive atmosphere consisting of a mixture with air of dangerous substances in the formof gas, vapour or mist is not likely to occur in normal operation but, if it does occur, will persist for a short period only. ZONE 0 ZONE 1 ZONE 2 ZONE 21 ZONE 22 ZONE 0 ZONE 1 ZONE 2 ZONE 21 ZONE 22 ZONE 1 ZONE 2 ZONE 21 ZONE 22 ZONE 1 ZONE 2 ZONE 0 ZONE 1 ZONE 0 Combustible Dust Hazards IEC 60079-31 - Electrical apparatus for use in the presence of combustible dust. Zone 20 A place in which an explosive atmosphere in the formof a cloud of combustible dust in air is present continuously, or for long periods or frequently. Zone 21 A place in which an explosive atmosphere in the formof a cloud of combustible dust in air is likely to occur in normal operation occasionally. Zone 22 A place in which an explosive atmosphere in the formof a cloud of combustible dust in air is not likely to occur in normal operation but, if it does occur, will persist for a short period only. Flexicon’s EXD barrier glands range can be used in Zone 1 and Zone 2 areas where Group A, B or C gases are present. As the gland does not add to the temperature of the enclosure, it does not have a temperature classification and so can be used with all temperature classes. Flexicon’s EXD barrier glands can be used in Zone 20, Zone 21 and Zone 22 where explosive dust may be present. Anti-Static Applications Clause 7.4 of EN60079-0 refers to the avoidance of a build-up of electrostatic charge on Group I or Group II electrical equipment. Electrical equipment shall be so designed that under normal conditions of use, maintenance and cleaning, danger of ignition due to electrostatic charges shall be avoided. This requirement is satisfied by suitable selection of thematerial so that surface resistance complies with either of the limits given b lowwhen m asured in accordance with 26.13; 109Ω measured at (50 ± 5) % relative humidity; or 1011Ω measured at (30 ± 5) % relative humidity. ZONE 0 ZONE 1 ZONE 2 ZONE 21 ZONE 22 ZONE 20 ZONE 0 ZONE 1 ZONE 2 ZONE 21 ZONE 22 Technical Data Hazardous Areas
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