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| Ex-Enclosures |
| We manufacture an extensive range of Ex-Enclosures, in aluminium and polyester materials, in accordance with EN 50 019 and EN 50 020.
Electrical equipment must have EN certification if it is to be used in explosive areas. Explosive areas are described as being sites where flammable substances can be mixed with air such that this mixture can inflame a device through a spark or when reaching certain temperatures. The main concerns with enclosures are high temperature of the connection terminals, electrical overloading of the cables and static electricity caused by plastic materials and assembly of your components. |
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Terms
Explosive area An area with explosive danger due to local circumstances. Explosive atmosphere A mixture of air and inflammable gas, vapours, mist or dust under atmospheric circumstances. The combustion propagates independently from the source of ignition. Danger of explosion An explosive atmosphere is being created through high temperature or sparks in the equipment. Division of explosive areas into zones Explosive areas have to be divided into zones depending on their probability of creating a dangerous atmosphere. A judgement as to the extent of safety control required can then be made. |
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Ignition Protection
In atmospheres where explosive mixtures, made of inflammable substances and air, cannot be prevented with primary explosion protection, special precautions have to be taken in order to prevent ignition sources. There are special building and construction regulations for all electrical equipment in explosive areas. The production of electrical explosion-proof equipment is permitted in different ignition conditions, according to the EN 50014 building regulations. Extended safety "e" EN 50 019 All necessary steps have been taken to prevent the possibility of inadmissible high temperature, sparks and electric arcs in the interior or exterior of all electrical equipment, when used under normal circumstances. Intrinsic safety "i" EN 50 020 The equipment used in explosive areas only contains intrinsic currents. The current is intrinsic when no spark and no thermal effect can be produced to cause ignition of the explosive atmosphere. This must be proven by defined test conditions which explain the normal working and fault conditions of the device. Intrinsic electrical equipment and intrinsic parts of relevant electrical equipment can be split in two categories:
an ignition when two faults occur in any combination. an ignition when a fault occurs under normal working conditions. Group classification of electrical equipment:
Temperature classification Hot surfaces are a major source of ignition for explosive mixtures. The temperature on the surface of an enclosure or any parts being accessible to explosive mixtures should not be any higher than shown in the table below, starting from 40ºC....
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Note!: Rolec Ex-Enclosures are licenced for temperature class T6
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Divisions of explosive areas into zones
Explosive areas have to be divided into zones depending on their probability of creating a dangerous atmosphere. A judgement as to the extent of safety control required can then be made. Zone 0 Contains an atmosphere of constant or long-term hazardous and explosive atmospheres due to gas, vapours or mist. This normally also includes the interior of receptacles and devices. Zone 1 Contains an atmosphere of occasional hazardous and explosive atmospheres due to gas, vapours or mist. This includes the following:
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Zone 2 In this zone short-term hazardous and explosive atmospheres are created. This can include the following:
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| Legal notice: copyright © 2000-2004 OKW Enclosures Ltd, UK. All rights reserved. Rev:2004.01.05 Rolec ® is the registered trademark of Rolec Gehäuse-Systeme GmbH, Germany. |
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