A valve body has in inlet, an outlet, and a port positioned between the inlet and outlet. An approach passage interconnects the inlet and the port and has a cross-sectional area that is greater than that of the port. One or more guide vanes are positioned within the approach passage and extend longitudinally along at least a portion of the approach passage so that a downstream end of the guide vanes is spaced apart from the port and the guide vanes divide the portion of the approach passage into sub-passages that have equal flow resistances.