Apparatuses and methods for urea dosing of an exhaust after treatment system are disclosed. Exemplary apparatuses include a chamber configured to receive pressurized gas at a first inlet, receive urea solution at a second inlet, and provide a combined flow of pressurized gas and urea to an outlet, a flow passage extending from the first inlet to a seating surface, and a valve member configured to move between an open position in which the valve member is spaced apart from the seating surface and a closed position in which the valve member contacts the seating surface. As the valve member moves from the open position to the closed position the valve member contacts the seating surface at a first location and wipes an area of the seating surface extending from the first location in a direction toward the flow passage.