Abstract: A butterfly valve wherein at least one cam is mounted on the valve shaft and located in a cam chamber associated with the valve disc. The cam cooperates with the cam chamber to rotate the valve disc between an open position and a closed position in alignment with and spaced from the valve seat at which point further rotation of the disc is prevented by stop means. The cam then further cooperates with the cam chamber to force the valve disc linearly into a seated position in engagement with the valve seat. Belleville springs engage the cam and force the valve disc away from engagement with the valve seat. A normal 90.degree. valve actuator may be used.

Abstract: Disclosed is a tank bottom internal valve housing. A low profile valve housing with a valve such as a butterfly valve and a means for opening and closing the valve is assembled to a saddle on the tank bottom by a number of bolts located around the periphery of the valve housing and engaging in threaded blind holes in the tank saddle. A discharge nozzle is mounted on the lower face of the valve housing in such a way that the discharge nozzle mounting can be sheared away from the rest of the assembly during, for instance, an accident without affecting the integrity of the valve housing itself.