Employee turned a valve on at the #267 shield on the 7W Longwall face to pressurize a 3/4"" hydraulic line supplying pressure to a Z-drill outby the face in the tailgate entry. When EE turned the valve on, it broke at the stem where it entered the connection port and struck EE on the right side of EE's face. Suffered a small fracture, contusion to eye and 3/4"" cut requiring sutures.