Firing apparatus for gun perforators

Claim 1

THE COMBINATION WITH A FORMATION TESTER INCLUDING A TUBING STRING, PACKER MEANS FOR INSOLATING THE ZONE TO BE TESTED FROM THE SUBMERGENCE PRESSURE OF WELL FLUID, A FORMATION TESTER VALVE OPERABLE TO CONNECT SAID ZONE WITH THE INTERIOR OF SAID TUBING STRING, THEREBY TO SUBJECT SAID ZONE TO THE REDUCED PRESSURE PRESENT IN THE TUBING STRING, AND A GUN PERFORATOR FOR PREFORMING SAID ZONE FOR FLOW OF FORMATION FLUIDS INTO SAID TUBING STRING, OF A FIRING APPARATUS FOR SAID GUN PERFORATOR, COMPRISING; RESTRAINING HAMMER OPERABLE TO FIRE SAID GUN PERFORATOR; RESTRAINING MEANS RESPONSIVE TO SUBMERGENCE PRESENCE TO MAINTAIN SAID FIRING HAMMER INOPERATIVE; AND A RELEASE MEANS RESPONSIVE TO REDUCTION IN PRESSURE, ON SETTING OF SAID PACKER FOR RELEASING SAID RETAINING MEANS, THEREBY TO PERMIT OPERATION OF SAID FIRING HAMMER AND FIRING OF SAID GUN PERFORATOR.