Abstract: Technologies are generally described for valve assemblies that include a valve body whose inner wall defines two ports and a controllable flow path that extends along the inner wall between the two ports of the valve body. Each port may be fitted with a corresponding gasket. A rotatable member disposed in the controllable flow path of the valve body may include a hemispherical-shaped body with a substantially flat disk-shaped surface portion, and a seal ridge formed about a perimeter of the substantially flat disk-shaped surface portion. During opening and closing operation, the seal ridge may be selectively engaged with either one of the gaskets reducing an initial contact surface, and thereby reducing friction between the rotatable member and the gaskets.

Abstract: Technologies are generally described for valve assemblies that include a valve body whose inner wall defines two ports and a controllable flow path that extends along the inner wall between the two ports of the valve body. Each port may be fitted with a corresponding gasket. A rotatable member disposed in the controllable flow path of the valve body may include a hemispherical-shaped body with a substantially flat disk-shaped surface portion, and a seal ridge formed about a perimeter of the substantially flat disk-shaped surface portion. During opening and closing operation, the seal ridge may be selectively engaged with either one of the gaskets reducing an initial contact surface, and thereby reducing friction between the rotatable member and the gaskets.