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exp

pressurized enclosure

7 Basic principle: The formation of an explosive atmosphere inside the enclosure is prevented by aprotective gas maintained at an overpressure in relation to the ambient atmosphere, and, if neces-sary, the interior of the enclosure is continuously supplied with protective gas which will diluteany combustible mixtures. R.Stahl can exercise a great deal of latitude when it comes to enclosure construction. The gamut ranges from individual systems in enclosures measuring 360 x 360mm to whole 40ft containers. The enclosure walls must only include components that have passed a type examination in accordance with Zone 1 criteria. Only approved Ex actuators and inspection windows as well as cable and cable glands/line entries are to be used. To meet the requirements for use in Zone 1, every prototype of a control unit is tested before delivery with 2 different gases. In this way, adequate gas dilution can be determined by means of the flushing volume. These measurements are carried out in our own testing laboratory. Based on our experience, we then select elec- trical apparatus and components for switchgear combinations appropriate for type of protection »pressurised enclosure«.

ENNEC II 2 G; EEx px IIC T4, Zone 1II 3 G; EEx pz IIC T4, Zone 2Class I, Zone 1, AEx px/pyClass I, Zone 2, AEx pzClass I or II, Div 1, Type X/Y Class I or II, Div 2, Type Z