FLOW SAFETY VALVE OF FORMATION TESTER Russian patent published in 2000 - IPC

FIELD: equipment for well testing in oil-and-gas industry. SUBSTANCE: flow safety valve includes body accommodating axial channels and check valve. The latter is of poppet type with a possibility of closing of axial channels and is connected with control unit which is made in the form of piston pair whose above piston hollow is provided with gaged compression spring. Above-piston hollow is communicated with pipe space, while under-piston is communicated with drill string-wellbore annulus. EFFECT: provided shutoff of fluid under critical pressure differential for prevention of collapses of drill pipes by mud external excessive pressure. 1 dwg