A ball valve is disclosed with an orifice to control the flow of fluids, in which the downstream seal is never directly exposed to erosive wear from the fluid flow. The orifice is only open in a limited range of the ball's rotation. Upon rotation of the ball from the full closed position, the orifice starts to open on the outlet side first, and after the outlet orifice is fully open, the orifice opens to the inlet side.
The size of the opening on the inlet side can be adjusted to control the flow rate of fluid through the orifice in the ball. When closing the valve, the inlet side closes first and then the outlet side. The orifice of the ball thus passes the outlet seal under no-flow conditions, and gross erosion of the outlet seal can be avoided.
