Is it possible to use Altivar 71 drive in Methane Gas atmosphere.

Methane is a flammable gas which creates explosive atmosphere.
So, using any type of electrical equipment in such environment is restricted based on ATEX, Ex and other (local) norms describing and dedicated for Hazardous Area Classification for Flammable Gases and Vapours.
So, if ATV71 has to be used in explosive atmosphere, the only solution is to close it inside special cabinet which is ATEX/Ex certified (means to isolate ATV71 from methane).

Released for:Schneider Electric India