Door that is impervious and resistant, essentially to a liquid fluid and/or a gaseous fluid, and is designed in particular to be installed in a high-security building, such as a nuclear power plant, comprising a frame structure extending substantially vertically when mounted and at least one door leaf which is in sealing contact with the frame structure when the door is closed, the door leaf or each door leaf comprising at least one sealed opening system (3, 4 or 4', 5) preferably in the lower part thereof, which can open automatically in response to a threshold pressure of liquid or gaseous fluid exerted on either the front or rear face of the corresponding leaf of said system and forcing the opening of the latter so as to allow the fluid to pass through, said system comprising on the one hand at least one opening formed through the leaf or each leaf and closed either by a shutter, which pivots by means of pivoting means, or by an ejectable panel, and on the other hand at least one pressure latching mechanism able to provide mechanical resistance to the opening of the shutter or each shutter, if necessary of the panel or each panel, and to be unlocked automatically by the effect of a threshold pressure of fluid exerted on one of the front or rear faces of the corresponding shutter, if necessary of the panel, and forcing the pivoting on opening, if necessary the ejection of the latter, characterised in that the or each latching mechanism comprises: - a first latching part integrated into the edge of the shutter, if necessary of the corresponding panel, and comprising a ball and a spring or other resilient element exerting a thrust pressure onto said ball, - a second latching part forming a latch integrated into the edge of the corresponding opening and comprising a receiving surface, substantially flush with said edge, in which a, preferably conical, recess is formed which is designed to receive said ball, which is able to provide mechanical resistance to the opening being supported by the effect of the pressure and thrust of the spring in said recess and is able to be disengaged from said latch under the effect of a threshold pressure of fluid exerted on one of the faces of the corresponding shutter, if necessary the panel, and forcing the pivoting on opening, if necessary the ejection of the latter, in that the or each latching mechanism comprises means for adjusting (5', 5") the pressure of the resilient element being exerted on the ball, and in that in the closed state of each shutter, if necessary of the panel or each panel, the or each ball is surrounded in the gap between the edge of the shutter, if necessary the edge of the panel and the edge of the opening, if necessary the edge of the panel by a gasket, for example a sealing washer, said gasket being clamped or compressed between said edges by being fixed onto one of the latter, for example by adhesion. - a first latching part integrated into the edge of the shutter, if necessary of the corresponding panel, and comprising a ball and a spring or other resilient element exerting a thrust pressure onto said ball, - a second latching part forming a latch integrated into the edge of the corresponding opening and comprising a receiving surface, substantially flush with said edge, in which a, preferably conical, recess is formed which is designed to receive said ball, which is able to provide mechanical resistance to the opening being supported by the effect of the pressure and thrust of the spring in said recess and is able to be disengaged from said latch under the effect of a threshold pressure of fluid exerted on one of the faces of the corresponding shutter, if necessary the panel, and forcing the pivoting on opening, if necessary the ejection of the latter,