A valve manifold assembly (10) for processing fluids wherein the manifold member (20) includes respective interface segments (58) to which are secured the valve members (12, 14, 16, 18). The interface segments typically are counterbored into the faces of the manifold member and include portals (62, 64) connected to passageways (66, 70) internal to the manifold member; and an alignment device such as a pin (84). The valve member includes a manifold mount body portion (24) which has a complementing alignment member such as an opening (104). The valve when positioned in the counterbored portion (88), and the pin is aligned with the alignment opening in the manifold mount body portion, ensures that the ports in the valve member and the manifold member are properly aligned. A manifold mount body portion of the valve includes an annular groove (90) which coacts with a clamping device (108, 110) to secure the valve in the respective counterbored portion. A sealing gasket (100, 102) surrounds the aligned ports to insure that no fluid leakage occurs between the ports.