The rotary valve “RS” in “ex” version allow installation of this component in potential explosive atmosphere , where is requested shockresistance and fl ameproof certifi cation, for to avoid propagation risk . Rotary valve “RS/ex” is in accordance with restrictive European norms “ Explosion Isolation Systems “ EN 15089 , with resistance certifi ed until 10 bars. Each valve supplied in this version has also conformity for Directives CE ATEX 94/9/ EC II1D for inside and II2DG for outside machine. The “RS/ex” can be supplied in cast iron GS400, G25, with nickel or chromium plating, stainless steel AISI304 or AISI316 , while transmission can be with chain drive or direct drive