Oil-vapor diffusion vacuum pump

Claim 1

IN A VAPOR DIFFUSION VACUUM PUMP HAVING A BOILER CONTAINING AND HEATING AN ORGANIC WORKING FLUID TO A VAPOR, AN EJECTOR COMPRISING AN INNER TUBULAR ELEMENT MOUNTED IN COMMUNICATION WITH SAID BOILER FOR RECEIVING VAPOR OF THE WORKING FLUID AND MEANS DEFINING VAPOR JET MEANS FOR DEVELOPING A VACUUM WITH SAID EJECTOR IN OPERATION, AN OUTER WALL CIRCUMFERENTIALLY OF SAID INNER TUBE EXTENDING AXIALLY OF SAID INNER TUBE AND SPACED OUTWARDLY THEREFROM DEFINING AN ANNULAR SPACE IN COMMUNICATION WITH SAID BOILER FOR RETURNING CONDENSED VAPOR OF SAID WORKING FLUID TO SAID BOILER, THE IMPROVEMENT WHICH COMPRISES SEAL MEANS IN SAID SPACE TO PRECLUDE WORKING FLUID IN A VAPOR PHASE FROM SAID BOILER ENTERING SAID ANNULAR SPACE AND ALLOWING WORKING FLUID IN A CONDENSED STATE TO RETURN TO SAID BOILER, SAID SEAL MEANS COMPRISING A PLURALITYOF COLLARS DISPOSED AXIALLY SPACED IN SAID TUBULAR SPACE EXTENDING INWARDLY DEFINING IN SAID SPACE ANNULAR GAPS OF DIFFERENT DIMENSIONS BETWEEN THE INNER TUBE AND SAID OUTER PERIPHERAL WALL EFFECTIVE TO ENTRAP CONDENSED WORKING FLUID IN A LIQUID PHASE TO FORM RESPECTIVE SEAL RINGS OF LIQUID WORKING FLUID AT EACH OF SAID GAPS, AND SAID GAPS BEING OF DIFFERENT RESPECTIVE DIMENSIONS AND THE DIFFERENT DIMENSIONS THEREOF DECREASING IN A DIRECTION TOWARD SAID BOILER.