Abstract: A partial diffuser is provided in a flow path of a pipe or valve, dividing the flow path into an unrestricted flow region, a greater restricted flow region, and a lesser restricted flow region. The flow path is defined by an inside wall, and the lesser restricted flow region is proximate to the inside wall. The greater restricted flow region is distal to the inside wall, and the lesser restricted flow region lies between the greater restricted flow region and the inside wall. In one embodiment three partial diffusers project into the flow path in a ball valve. An inlet flow diffuser is installed in the inlet to the valve, and a valve element inlet flow diffuser is installed at an inlet to a valve element in the valve diametrically opposed to the inlet flow diffuser. A valve element outlet flow diffuser is installed in an outlet from the valve element at a position diametrically opposed to the valve element inlet flow diffuser.