Valve and gasket tolerant to pressure-differentials

A vacuum-tolerate gasket-valve seal member comprising:

• a hollow cylinder having a wider end, a narrower end, and a tubular wall connecting the wider end to the narrower end;
• an outer radial flange attached to an outer facing of the tubular wall at a terminal edge of the wider end and disposed concentrically outward in a plane parallel with an inner cylinder diameter;
• an inner radial flange attached to an inner facing of the tubular wall at a terminal edge of the narrower end and disposed to project radially inward in a plane parallel with an outer cylinder diameter so that diametrically opposed inner, axially-aligned facings of the inner radial flange define a central aperture at the terminal edge of the narrower end;
• and
• a plurality of support ribs formed contiguously with the inner radial flange and extending upward toward the wider end along the inner facing of the tubular wall and wherein at least support one rib is formed flush with a portion of the inner, axially-aligned facings;
• wherein the hollow cylinder, the outer radial flange, the inner radial flange, and the plurality of support ribs are all integrally formed from a resilient, deformable olefin or thermoplastic elastomer material;
• and
• wherein the inner cylinder diameter at the wider end is larger than the outer cylinder diameter at the narrower end.