Flask for freeze drying with adjustable seal

Claim 1

A vessel assembly for freeze drying formed of materials reisstant to chemical action and extremes in temperature and pressure comprising a sample container having a mouth and an interior wall surface at an open end thereof, a cover assembly, said cover assembly being adapted for mounting in a positive fluid-tight manner to close said mouth, said cover assembly including a compression plate and a retainer plate, said retainer plate having an annular channel on an upper surface, said retainer plate being integral with an upstanding neck, said neck having a passageway for attachment to a vacuum source for the application of vacuum to said sample container, said passageway being in communication with the interior of said sample container when said cover assembly is mounted on said mouth of said container, said compression plate having a radially extending flange providing a seat for placement of said cover assembly on said mouth, said retainer plate being adjustably movable towards said compression plate, a resilient annular sealing means in a given position between said retainer plate and said compression plate, said retainer plate and said compression plate engaging said sealing means on opposing sides and compressing said sealing means for radial expansion outward while being retained in said given position, said compression being caused by the movement of said retainer plate towards said compression plate for the engagement of said compression sealing means with said interior wall surface of said sample container in a reliable thermally resistant fluid-tight seal while retaining said constant radius.