Abstract: A valve body having an opening closed by a cover through which may be mounted or demounted a non-return obturator which is mobile along an upstream-downstream axis, the obturator being installed by first securing a first member to the valve body and then securing the obturator and its spring and then securing a second member.

Abstract: A valve designed for the prevention of leakage between two or more ports when the valve is in its off position and where leakage occurs at a port seal as shown and described. In this design, each port is sealed when the valve is in the off position, and an open area vented to atmosphere is provided between each of the port seals, whereby if a seal should leak, the fluid will pass to the atmosphere by way of a vent, and will not come in contact with any other sealed port in the valve. The vented chamber separates each port seal from other port seals in the valve. The vented chamber is exterior to the valve and is not a part of the inside of the valve member such as a passage therethrough.