Safety closure for containers

Claim 1

IN A CONTAINER STRUCTURE, IN COMBINATION, A CONTAINER VESSEL HAVING AN OPENING-DEFINING NECK PORTION BEARING ON ITS OUTER SURFACE AN EXTERNAL SCREW THREAD OF ONE ROTATIONAL SENSE AND BEARING ON ITS INNER SURFACE AN INTERNAL SCREW THREAD OF OPPOSITE ROTATIONAL SENSE; AND A CLOSURE DEVICE COMPRISING A SCREW CAP DIMENSIONED TO FIT OVER SAID NECK PORTION FOR CLOSURE THEREOF AND BEARING AN INTERNAL SCREW THREAD OF SAID ONE ROTATIONAL SENSE FOR MESHING WITH SAID EXTERNAL SCREW THREAD OF SAID NECK PORTION, AND A PLUG DIMENSIONED TO PASS THROUGH THE OPENING DEFINED BY SAID NECK PORTION AND HAVING A SURFACE PORTION BEARING AN EXTERNAL SCREW THREAD OF SAID OPPOSITE ROTATIONAL SENSE FOR MESHING WITH SAID INTERNAL SCREW THREAD OF SAID NECK PORTION; SAID PLUG BEING SECURED TO SAID CAP AND PROJECTING THEREFROM SO AS TO EXTEND THROUGH SAID OPENING WHEN SAID CAP IS IN POSITION CLOSING SAID NECK PORTION; SAID INTERNAL THREAD OF SAID CAP AND SAID EXTERNAL THREAD OF SAID PLUG BEING RELATIVELY POSITIONED TO ENGAGE SAID EXTERNAL AND INTERNAL NECK THREADS RESPECTIVELY AS SAID CLOSURE DEVICE IS MOVED BETWEEN A FIRST POSITION IN WHICH SAID CAP FULLY CLOSES SAID NECK PORTION AND A SECOND POSITION IN WHICH SAID CLOSURE DEVICE IS FULLY DISENGAGED FROM SAID NECK PORTION, AND TO PREVENT SIMULTANEOUS ENGAGEMENT OF SAID CAP THREAD AND SAID PLUG THREAD WITH SAID EXTERNAL AND INTERNAL NECK THREADS RESPECTIVELY AS SAID CLOSURE DEVICE IS MOVED BETWEEN SAID FIRST AND SECOND POSITIONS.