Sliding gate valve sector-type storage tank closure

Claim 1

A SECTOR-TYPE STORAGE-TANK CLOSURE COMPRISING A CASING HAVING AN UPPER, AN INTERMEDIATE AND A LOWER PORTION, SAID INTERMEDIATE PORTION BEING AT LEAST PARTLY WIDER THAN THE OTHER PORTIONS, A SECTOR-SHAPED SOLID SLIDE PLATE SWINGABLE BETWEEN SAID UPPER AND SAID INTERMEDIATE PORTIONS AND HAVING AN OPEN AND A CLOSED POSITION, SEAT MEANS SLIDALBY CONTACTED BY SAID PLATE AND ENGAGING SAID PLATE WHEN THE LATTER IS IN ITS CLOSED POSITION, PIVOT MEANS FOR LATERALLY SHIFTING SAID PLATE, AN INLET OPENING IN SAID UPPER PORTION AND A DISCHARGE OPENING IN SAID LOWER INTERSUBSTANTIALLY ALIGNED WITH SAID INLET OPENING, SAID INTERMEDIATE PORTION SLOPING INWARDLY FROM THE EDGES OF SAID PLATE TOWARD SAID DISCHARGE OPENING IN SAID CLOSED PLATE POSITION, AND SAID INTERMEDIATE PORTION DEFINING, WHERE IT SLOPES INWARDLY, AT LEAST PART OF THE FLOW PATH THROUGH THE CLOSURE, AT LEAST ONE PROJECTION ON SAID INTERMEDIATE PORTION SUBSTANTIALLY PERPENDICULAR WITH RESPECT TO THE PLANE OF SAID PLATE AND PROVIDING THEREFOR A SLIDING SUPPORT, AND ELONGATED SEALING MEMBERS RESPECTIVELY ENGAGING OPPOSED FACES OF SAID PLATE AND SITUATED IN A CENTRAL REGION OF SAID CASING SUBSTANTIALLY MIDWAY BETWEEN SAID OPEN AND SAID CLOSED PLATE POSITIONS.