A mixing hub for use in semiconductor processing tools is provided. The hub may include a plurality of ports arranged about an axis, a mixing chamber, and a plurality of flow paths. Each of the flow paths may fluidically connect a corresponding one of the ports to the mixing chamber and each flow path may include a first passage, a second passage, and a valve interface. Each valve interface may be configured to interface with a valve such that the valve, when installed in the valve interface, is able to regulate fluid flow between the first passage and the second passage. Each valve interface may be located between a first reference plane that is perpendicular to the axis and passes through the corresponding port and a second reference plane that is perpendicular to the axis and passes through the mixing chamber.