Double seal including means for indicating leaks

Claim 1

IN A SEALING DEVICE FOR SEALING A JOINT OF TWO TELESCOPED ELEMENTS MOVABLE RELATIVELY TO EACH OTHER AND SEPARATING SPACES CONTAINING FLUIDS UNDER DIFFERENT PRESSURE, TWO SPACED SEALING MEANS DEFINING A CHAMBER BETWEEN THE TWO ELEMENTS, ONE OF SAID SEALING MEANS BEING INTERPOSED BETWEEN THE SPACE CONTAINING FLUID UNDER A RELATIVELY HIGH PRESSURE AND SAID CHAMBER, THE SECOND OF SAID SEALING MEANS BEING INTERPOSED BETWEEN SAID CHAMBER AND THE SPACE CONTAINING FLUID UNDER A RELATIVELY LOW PRESSURE, SAID FIRST SEALING MEANS BEING MOUNTED IN ONE ELEMENT AND OPPOSED TO A SURFACE OF THE OTHER ELEMENT WHEREBY THE SEAL MAY BE MADE TIGHT UPON RELATIVE MOVEMENT OF THE TWO ELEMENTS IN ONE DIRECTION AND MAY BE OPENED UPON RELATIVE MOVEMENT OF THE TWO ELEMENTS IN THE OPPOSITE DIRECTION, SAID SECOND SEALING MEANS BEING CONNECTED TO ONE OF SAID ELEMENTS AND IN SLIDING ENGAGEMENT WITH THE OTHER ELEMENT THEREBY AFFORDING RELATIVE MOVEMENT OF THE TWO ELEMENTS IN OPPOSITE DIRECTIONS FOR OPENING AND CLOSING THE FIRST SEALING MEANS, AND A CONDUIT CONNECTING SAID CHAMBER TO THE OUTSIDE OF THE DEVICE FOR CHECKING THE PRESENCE OF FLUID OF THE RELATIVELY HIGH PRESSURE SPACE IN SAID CHAMBER.