... , borehole electric control and other electrical continuity, which comply with the relevant regulations in National Standard GB3836.8-2003 & ... Gas Atmosphere Part 8: Type of Protection ‘n’”. Explosion-proof sign is ExnII T4,II 3G EExnA II T4,type ... reliable contact, convenient wiring, better air tightness & insulation, together with such features as waterproof, dust prevention, shockproof, etc.Main ...