Bung for barrel

Claim 1

A BUNG OF RESILIENTLY YIELDABLE MATERIAL FOR SEALING A GENERALLY CYLINDRICAL BUNG HOLE IN A BARREL OR THE LIKE, COMPRISING: A SEALING SECTION AND A COMBINED CLOSURE AND ACTUATOR SECTION FOR THE SEALING SECTION; THE LATTER COMPRISING A GENERALLY CYLINDRICAL SHELL HAVING AN INNER END AND AN OUTER END; THE EXTERNAL WALL OF THE OUTER PORTION OF SAID SHELL BEING ADAPTED FOR SEALING ENGAGEMENT WITH THE WALL OF THE BUNG HOLE; AN EXTERNAL ANNULAR SHOULDER FORMED INTERMEDIATE THE ENDS OF SAID SHELL TO ENGAGE THE INNER WALL OF THE BARREL AROUND THE BUNG HOLE; THE INNER PORTION OF SAID SHELL COMPRISING A GUIDE SKIRT CONVERGING INWARDLY FROM SAID SHOULDER TO FACILITATE INSERTION OF SAID BUNG; SAID CLOSURE AND ACTUATOR SECTION INCLUDING A CENTRAL, INWARDLY EXTENDING HOLLOW COLUMN CLOSED AT ITS INNER END AND OPEN AT ITS OUTER END; A FIRST, GENERALLY CYLINDRICAL, SLEEVE SURROUNDING SAID COLUMN IN SPACED RELATION AND CONNECTED AT ITS OUTER END TO THE OUTER END OF THE COLUMN; AND A SECOND, OUTWARDLY DIVERGING, FRUSTOCONICAL, SLEEVE SURROUNDING SAID FIRST SLEEVE AND CONNECTED AT ITS INNER END TO THE INNER END OF THE FIRST SLEEVE AND CONNECTED AT ITS OUTER END TO THE OUTER END OF SAID SHELL TO COMPLETE THE CLOSURE OF SAID BUNG; THE FRUSTO-CONICAL SHAPE OF SAID SECOND SLEEVE SERVING TO APPLY SUBSTANTIAL RADIAL OUTWARD FORCES TO SAID SHELL IN RESPONSE TO THE AXIAL FORCES IMPOSED ON SAID COLUMN AND FIRST SLEEVE BY FLUID PRESSURE WITHIN THE BARREL, AND THUS TO INCREASE THE SEALING EFFECT OF SAID BUNG.