Sill and opening-leaf assembly for a door that essentially is fluid-tight to a liquid or gaseous fluid and is intended to seal an opening separating two spaces in a building or monument

A sill and opening-leaf assembly for a door that is fluid-tight and intended to seal an opening separating two spaces of a building, comprising:

• an opening leaf having a lower edge face which is situated, when mounted, facing a floor surface, and a sill configured to prevent the passage of fluid through a bottom part of the door between the lower edge face and the floor surface,
• wherein the sill includes:
• at least one flat and elongate gasket element, which includes a front longitudinal surface, a rear longitudinal surface, and a longitudinal attachment side, wherein the gasket element is attached via the longitudinal attachment side to the lower edge face of the opening leaf;
• and
• at least one groove including a bottom and two longitudinal edges, the groove made in the floor surface and extending across the opening, wherein the gasket element when mounted, is configured to engage with either of the two longitudinal edges of the groove and being allowed to travel into the groove depending on whether a pressure force is exerted by the fluid from one of the two spaces on the front longitudinal surface or rear longitudinal surface of the gasket element.