Safety lid for pressure tank

Claim 1

IN COMBINATION WITH A PRESSURE TANK PROVIDING AN ACCESS OPENING SURROUNDED BY A PROTRUDING ANNULAR NECK AND HAVING A PLURALITY OF BAYONET STUDS EXTENDING RADIALLY FROM SAID NECK AT SPACED INTERVALS OF THE CIRCUMFERENCE, A SAFETY LID THEREFOR PROVIDING A CAP-PIECE COMPRISED OF A CENTRALLY APERTURED CROWN SECTION ARRANGED TO OVERLIE THE OPENING AND HAVING A SKIRT SECTION WHICH FITS OVER THE NECK, SAID SKIRT SECTION HAVING SLOT COMPLEMENTS OF SAID BAYONET STUDS FORMED THEREIN AND EACH CHARACTERIZED IN THAT THE LOWER EDGE THEREOF IS STEPPED TO PROVIDE AN UPPER-LEVEL AND A LOWER-LEVEL SEAT FOR THE RESPECTIVE STUD SPACED APART BOTH AXIALLY AND CIRCUMFERENTIALLY OF THE CAPPIECE, SAID LOWER-LEVEL SEAT PRESENTING A TERMINAL PROMINENCE LOCKING THE STUD AGAINST ACCIDENTAL DISLODGEMENT FROM THE SEAT, SAID PROMINENCE BEING AXIALLY SPACED BENEATH THE UPPER EDGE OF THE SLOT A DISTANCE ONLY SLIGHTLY GREATER THAN THE RESPECTIVE DIAMETER OF THE STUD, AN EXPANDABLE SEALING RING CARRIED BY THE CAP-PIECE SO AS TO UNDERLIE THE CROWN SECTION THEREOF AND CHARACTERIZED IN THAT THE SAME IS MADE EFFECTIVE TO PRODUCE A PRESSURE SEAL BETWEEN THE RIM OF THE NECK AND THE CAP-PIECE UPON BEING SUBJECTED TO A FLATTENING DEFORMATION UNDER FORCE OF COMPRESSION PRESSURE EXERTED UPON THE RING IN A DIRECTION ENDWISE TO ITS AXIS, AND COMPRESSION MEANS OPERATIVE INDEPENDENTLY OF TURNING OF SAID CAP-PIECE RELATIVE TO SAID TANK AND CARRIED BY SAID CAP-PIECE FOR EXERTING SAID COMPRESSION PRESSURE UPON THE SEALING RING, THE AXIAL DISTANCE FROM THE UPPER EDGE OF EACH SAID SLOT AT A POINT DIRECTLY ABOVE THE RESPECTIVE PROMINENCE TO THE CENTER OF THE SEALING RING WHEN THE RING IS COMPRESSED BY SAID COMPRESSION MEANS BEING GREATER THAN THE AXIAL DISTANCE FROM THE TOP OF THE STUDS TO THE UPPER RIM OF THE TANK NECK WHEREBY SAID SEALING RING CANNOT BE DEFORMED INTO SEALING RELATION WITH SAID NECK UNTIL SAID CAP-PIECE IS TURNED SUCH AS TO ADVANCE SAID STUDS IN SAID SLOTS TOWARD SAID UPPER-LEVEL SEAT BEYOND SAID PROMINENCES AND WHEREBY SAID CAP-PIECE CANNOT BE TURNED IN THE COUNTER DIRECTION BEYOND SAID LOWER-LEVEL SEAT WITHOUT UNSEALING SAID RING.