EE WAS GETTING READY TO DISCONNECT A STRING OF AMTRAK CARS REQUIRING HIM TO SHUT OFF THE AIR TOTHE 2 AIR BRAKE LINES. HE THOUGHT HE FORGOT TO SHUT OFF THE AIR IN THE LINE WHEN IN REALITY THE Y WERE ALREADY IN THE OFF POSITION. INSTEAD HE TURNED THE VALVES TO THE ON POSITION SENDING 150PRI OF COMPRESSED AIR THROUGH THE HOSES STRIKINGHIM IN THE FACE.