Abstract: A separator tank assembly comprising a cast hollow tank and a cast lid. The cast hollow tank has a closed end and an open end having a first opening and a second opening. The cast lid has a first passage configured for fluid communication with the tank first opening and a second passage configured for sealed fluid communication with the second opening. The first passage is formed with an integral port configured to receive a pressure control valve and the second passage is formed with an integral port configured to receive an oil filter and wherein the tank is configured such that air having undergone primary separation flows through the first opening and oil within the tank flows through the second opening.