Abstract: Apparatus is disclosed which is adapted for connection to a drilling conduit beneath a drilling rig floor for diverting pressurized well bore fluid in the conduit from the rig and sealing the annulus between a pipe or other object and the conduit or closing the vertical flow path of the conduit in the absence of any object in the conduit. The apparatus includes a housing, an annular packing element and two annular pistons. The housing is provided with two outlet passages in its wall. A first piston covers one outlet passage in the housing wall for preventing fluid communication between that outlet passage and the interior of the housing when it is in a nonactivated position and for aligning a first hole in the piston wall with the outlet passage for allowing fluid communication when the piston is in an activated position.