Electrically heated mantle with a seal arrangement

Claim 1

In combination: a heating mantle comprising a tubular frame being closed at the bottom and open at the top, said frame having inner and outer spaced walls, electrical heating means in said frame and being attached to said inner walls, heat-insulating material filling the space between said inner and outer walls, the top of said frame having an aperture through which a vessel extends while being heated by the heating means of said mantle, seal means on said top defining a channel surrounding said aperture and opening radially inwardly toward the center of said aperture while being closed toward the top and bottom and on the radially outer side by confining walls, said aperture providing only a small radial clearance about said vessel and said mantle supporting a vessel introduced through said aperture at a level such that the vessel presents an annular surface toward said channel, a flexible hollow inflatable annular ring confined in said channel and adapted to expand when inflated, said ring when uninflated permitting a vessel to be freely mounted in or removed from said aperture and when inflated expanding so as substantially to fill said channel and seal against the confining walls thereof and also expanding radially inwardly into sealing engagement with said annular surface of said vessel, and fluid connection means for inflating and deflating said ring.