Patent ID: 8302693

Claim:
A firing head for pyrotechnic well tools comprising: an axially elongated tool body having an aperture plugging means for closing a restrictive aperture within the bore of a pipe string; a fluid flow conduit within said tool body for transfer of fluid through said tool body to by-pass an aperture closed by said plugging means; axially translated first piston means in said flow conduit having a first position that obstructs fluid flow from a first port through said conduit and a second position that enables fluid flow through said first port; structural obstruction means for preventing the translation of said first piston means in a first axial direction along said flow conduit from said first position; retaining means for preventing the translation of said first piston means in a second axial direction along said flow conduit from said first position, said retaining means releasing said first piston to said second direction translation at a predetermined fluid pressure on a first side of an aperture closed by said plugging means whereby translation of said first piston in said second direction opens said conduit to fluid flow in said first direction; and, firing pin means for striking percussion ignition means to initiate a pyrotechnic well tool, said firing pin means secured to said first piston means by latching means, said latching means being released by translation of said first piston means in said second direction.