Drop-on-demand inkjet printing device (10) comprising a through-flow print head (20) having nozzles (22) and a fluid circulation system comprising a main reservoir (30), a supply buffer tank (38), a return manifold (64), wherein the main reservoir (30) is connected to the supply buffer tank (38) wherein the supply buffer tank (38) is in fluid communication with the nozzles (22) print head (20) the nozzles (22) being in fluid communication with the return manifold (38) wherein the return manifold (64) is connected to the main reservoir (30) and both are arranged in height with respect to the nozzles (22), wherein the supply buffer tank (38) is provided with a lockable conduit (56) connecting the supply buffer tank (38) to the main reservoir (30).