• • • • Explosion protection history and legal provisions.

    • The first contribution to explosion safety was made in 1815 by the English chemist Sir Humphry Davy, who developed an oil lamp that prevented the spread of flames using a closely-spaced mesh screen. The elementary experiments carried out by Dr. Karl Beiling, a mining engineer, related
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    • to the special protection of electric motors and apparatus in coal mines against fire, became a decisive step in developing explosion protection.The principles of designing devices to protect electrical machines, transformers, and switchgear against the effects of flame, published in 1912, were based on the results of these experiments.
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    • The following types of protection have been adopted as protective measures:

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Since 1924, incandescent lamps were only allowed to illuminate dangerous areas while the luminous element was hermetically sealed. Incandescent lamps had to be protected by durable glass, which closed the lamp socket tightly.

• Light switches were to be installed outside hazardous areas, and in the event of a malfunction or lack of explosion-proof lighting, access to these places was allowed only with a protective lamp. Therefore, in general, electrical installations were not used in hazardous locations.

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  Machines with slip rings or commutators had to be designed so that the slip ring or commutator was closed and the enclosure was thoroughly purged under overpressure with outside air or suitable gas. The purging must begin before the machine is turned on, or the machine must be built into a fireproof enclosure. This requirement is applied to all places where explosive gas or vapor-air mixtures are present.

  

  In production and workplaces, hazardous areas can occur wherever the first two conditions for an explosion are met. Typical dangerous regions are formed at, Chemical Plants, Oil Refineries, Enamel Factories , Paint Workshops, Sewage Disposal Plants, Mills and stores for crushed products and other flammable dust, In-tank installations and places where flammable gases, liquids, and solids are loaded.

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  The first two factors – combustible agent and air – must be present in sufficient quantities to form an explosive atmosphere. Legislative definitions of explosion protection, arising from occupational health and safety regulations, apply to workplaces. For this reason, explosion protection is usually limited to describing reactions with oxygen in the air. Oxidation reactions are typically accompanied by an increase in heat and pressure and therefore meet the criteria for an explosion.

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  It is generally accepted that a volume of 10 liters of an explosive mixture in a confined space can cause harm, especially to people. For this reason, any area in which such a volume of an explosive mixture can collect is called a potentially explosive atmosphere.