Apparatus for limiting entry of air into flare stack

Claim 1

IN A FLARE STACK ASSEMBLY, A VERTICALLY DISPOSED FLARE STACK HAVING AN OPEN UPPER END, A VERTICALLY DISPOSED TUBE FORMING A PART OF SAID STACK AND POSITIONED NEAR THE UPPER END THEREOF FOR RECEIVING WASTE GAS AT ITS LOWER END HAVING A MOLECULAR WEIGHT LESS THAN THAT OF AIR, SAID TUBE HAVING AN OPEN UPPER END FOR ESCAPE OF SAID WASTE GAS, AN INVERTED CUP-SHAPED MEMBER HAVING A CLOSED UPPER END SPACED ABOVE AND OVER THE UPPER END OF SAID TUBE AND A CYLINDRICAL WALL SURROUNDING THE EXTERIOR OF SAID TUBE IN SPACED RELATIONSHIP PROVIDING A FIRST ANNULAR SPACE BETWEEN THE EXTERIOR OF SAID TUBE AND THE INTERIOR OF SAID CYLINDRICAL WALL IN WHICH THE WASTE GAS ESCAPING THROUGH THE UPPER END OF SAID TUBE MAY MOVE DOWNWARDLY, A HOUSING SURROUNDING SAID CYLINDRICAL WALL IN SPACED RELATIONSHIP PROVIDING A SECOND ANNULAR SPACE BETWEEN THE INTERIOR OF THE HOUSING AND THE EXTERIOR OF SAID CYLINDRICAL WALL IN WHICH THE WASTE GAS ESCAPING THROUGH THE LOWER END OF THE FIRST ANNULAR SPACE MAY MOVE UPWARDLY, MEANS CLOSING THE LOWER PORTION OF SAID HOUSING WITH RESPECT TO SAID TUBE, MEANS CLOSING THE UPPER END OF SAID HOUSING WITH RESPECT TO SAID FLARE STACK SO THAT THE WASTE GAS FROM THE SECOND ANNULAR SPACE MAY ESCAPE THROUGH THE OPEN UPPER END OF THE FLARE STACK, A PLURALITY OF ELEMENTS CIRCUMFERENTIALLY SPACED FROM EACH OTHER ADAPTED TO PARTIALLY OBSTRUCT THE UPPER END OF SAID SECOND ANNULAR SAPCE, MEANS SUPPORTING SAID ELEMENTS FOR MOVEMENT TO POSITIONS UNOBSTRUCTING SAID SECOND ANNULAR SPACE IN RESPONSE TO THE FLOW OF WASTER GAS, AND SAID ELEMENTS BEING ARRANGED TO MOVE TO POSITIONS TO PARTIALLY OBSTRUCT THE UPPER END OF SAID SECOND ANNULAR SPACE UPON INTERRUPTION OF THE UPWARD FLOW OF WASTE GAS.