Motor units classification

The classification of motor oils has not been completed in the ISO standard because the technical differences between motors in different parts of the world, particularly Europe and the United States, make the implementation of a single system of classification and specifications very difficult. In practice, different systems coming from national or international organizations are used. The best known is the SAE viscosity classification from the Society of Automotive Engineers, developed in the United States. 

The compressor or blower installation in a typical refinery or chemical process unit is not out-of-doors completely. Some form of shelter often is provided, ranging from only a roof to a completely closed building. When process equipment such as a centrifugal gas compressor, which is not hazardous in normal operation, is present in the shelter, the hazard classification depends on the extent to that which the shelter restricts ventilation. The extent of the shelter provided determines the area classification and the type of motor enclosure that should be applied. 

In Division 1 areas, motors and generators must be either explosion-proof or approv ed for the classification by meeting specific requirements for a special ventilation system, inert gas-filled construction, or a special submerged unit. Although explosion-proof motors are expensive, they normally are available. Explosion-proof generators normally are not available. 

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