Myths about pre-start purging-ventilation and pressurization in motors of zone 2: Do you really need them? use Ex nA motors safely

More than 90% of electric motors are operating in Zone 2 explosive gas atmosphere for S1 to S10 applications such as pumps, reciprocating or centrifugal compressors etc. There have been a few recordable incidents in offshore or near-shore facilities in the North Sea within the last twenty years. As a result, a number of safety notices were issued from the Department of Energy- UK, for the use or application of pre-start ventilation or pre-start purging or purged and pressurization on existing or new high voltage motors. The authors discuss the importance of such features in Ex nA motors with respect to the present and most up to date IEC 60079-15 standard of Ex nA motors. At the same time various applications, associated risks, and proper selection of this expensive large motor feature is discussed. Different aspects of design and application is considered comparing North American and IEC standards in terms of safety to identify a clear selection of such features. Ultimately, this paper provides the guidance for those contemplating this expensive design when one could seemingly select and apply the right Ex nA motors for the right application and right location without such features.