An exhaust gas purification system includes a tank for storing a fluid and a mounting plate coupled to the tank. A baffle is positioned inside the tank below the mounting plate. The baffle has an outer wall defining an interior cavity and an opening. A sensor is positioned in the interior cavity for detecting a condition of the fluid. A supply conduit extends through the mounting plate into the tank. A return conduit extends through the mounting plate into the tank and has an outlet positioned to discharge a return fluid below the opening and exterior to the baffle and the interior cavity.