The Ful-Flo Hydraulic Circulating Valve is a Ful-Flo tool. It can be run above or below the tester valve. When runs below, the tool serves as a bypass around the packer and helps relieve swabbing effect when sting out or down hole; when the tool is run above the tester valve, it can serve as a circulating valve to circulate out the formation fluid which is left in the pipe string after testing.