A separator tank and a gas compressor having a separator tank are provided. The separator tank includes a tank body defining an inner volume, a tank inlet pipe providing fluid communication with the inner volume of the tank body, wherein the tank inlet pipe tangentially penetrates the tank body and is oriented to direct fluid entering the tank body in a spiral fluid flow pathway, and a sump tube positioned to collect fluid flowing within the tank body, the sump tube comprising a vertically oriented opening oriented to align and capture fluid flowing along the spiral fluid flow pathway.