I see many ex proof manufactures use fans with AMCA type A,B or C but I dont which one is suitable for each hazardouse location. Is there any clear referance or standerd???
XP is not required in a D2 area.
IMO it is mostly a design choice in a D2 area.
Keep in mind a D2 area is one where the area is hazardous only in the event of some kind of unlikely failure for very short periods of time. The chance of the fan creating a spark either from static buildup or by a sparking material striking something that might cause a spark is at the same time that the area becomes hazardous is pretty low.
Having said that, this seems like something that would best be looked at by a competent someone intimately familiar with the actual application, and not by a passerby on the Internet.
the materials the fan itself is made of is not covered by the NEC, only the electrical part of the fan.