EZQ 20/4 E E Ex e - Maico fans

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PLANNINGINSTRUCTIONSEZQ 20/4 E E Ex eReplacement of combustible materialThe build-up of potentially dangerous, explosive atmospheres can be prevented by the avoidance of or the reduction in the use ofcombustible materials. One example for this is the replacement of combustible solvents or cleaning agents by water-based solutions.Another option is to dampen the dust or to use highly viscous products, so that it is no longer possible to disturb the dust. [EXAM]InertisationA potentially dangerous, explosive atmosphere can also be avoided by thinning the oxygen in the air inside the equipment or by thinning thefuel with chemical, non-reactive (inert) material. This protective measure is known as inertisation. [EXAM]As a rule, inertisation by the use of gases can only be used in closed equipment, where only a relatively limited gas volume exchange perunit is possible.If an inert gas escapes from the equipment through openings that are normally there or that are caused by an error, this can represent adanger to the operator by reducing the level of oxygen and increasing the risk of suffocation. If combustion gasses are used as inert gasses,an escape of gas in this case can lead to the operator being poisoned.Secondary explosion protectionIf it is not possible to prevent the build-up of an explosive atmosphere, measures must be implemented to avoid the igniting of the explosiveatmosphere. This is achieved by measures that avoid the occurrence of ignition sources.The various types of ignition sources and their effects must be known, in order to define effective protective measures.Ignition sourcesThe following ignition sources can occur in commercial and industrial operations:■ Hot surfaces■ e.g. radiators, cooker hobs, heating boiler, heated machine parts, ...■ Flames and hot gases■ e.g. Bunsen burners, candles, matches, open-flame heating■ Mechanically generated sparks■ Electrical equipment:■ Opening and closing electrical circuits, e.g. light switches, electrical motors, switching on a refrigerator, heating system burnersApplication example: Ignition protection concept, with AC motor fans from MAICOThe potential source of ignition with MAICO fans is their hot surfaces.This is caused by the dissipated energy from the motor.In normal operation, the surface temperature reaches a stable level after some time. In the case of malfunctions, e.g. a blockedimpeller, this temperature can rise significantly in a very few seconds. Without appropriate protective measures, the ignitiontemperature of an explosive atmosphere could be exceeded and as a result, an explosion could be triggered.The protective measures are based on monitoring the temperature of the motor. For this purpose, there are PTC thermistorsbuilt into the motor winding, which are connected to a separate MVS 6 triggering device. When a particular maximumtemperature is exceeded, the MVS 6 switches the fan off, giving you a reliable way of preventing an ignition temperature levelbeing reached.Further protective measures have been implemented in the external, mechanical parts of the fan. These address in particularfriction with rotating parts, the build-up of static electricity and the unit's flammability.Version: 17.12.2013 - MAICO VENTILATOREN, www.maico-fans.com - We are not responsible for mistakes or printing errors and retain theright to make technical modifications without giving prior noticePage 22
PLANNINGINSTRUCTIONSEZQ 20/4 E E Ex e■ Sparks caused by friction, grinding or striking, e.g. nailed shoes on cement, rusty iron on aluminium, hammer on metal. There are tools,e.g. sockets sets made of material that does not generate sparks.Type of protection Function principle Main application"e"Increased safetySafety measures have beenintroduced to prevent theoccurrence of inadmissibly hightemperatures or sparks in theinner or outer parts.Terminal boxes, motors, lights"d"Pressure-proof housingParts that could ignite anexplosive atmosphere areinstalled in a housing that canwithstand the pressure of anexplosion and prevents transferto the surrounding explosiveatmosphere.Switching devices, motors,transformers, heaters"p"PressurisationThe build-up of an explosiveatmosphere within the housingis prevented by an ignitionprotection gas, which maintainsan excess pressure higherthan that of the surroundingatmosphere.Switching and control cabinets,analysis equipment, largemotors"i"Intrinsic safetyThe equipment containsintrinsically safe power circuits,which guarantee that nosparks or thermal effects cancause the ignition of explosiveatmospheres.Measurement and controltechnology, communicationstechnology, sensors"q"Powder fillingParts which could become asource of ignition are fixedin their position and thencompletely surrounded with afilling agent, in order to preventthe ignition of an externalexplosive atmosphere.CapacitorsVersion: 17.12.2013 - MAICO VENTILATOREN, www.maico-fans.com - We are not responsible for mistakes or printing errors and retain theright to make technical modifications without giving prior noticePage 23
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EZQ 20/4 E E Ex e - Maico fans

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