A novel solution is proposed for processing a test tube transported on a test tube carrier by a conveyor so that spilling of the liquid in the test tube is reduced or even prevented, particularly an arrangement for sequencing and guiding travel of test tube carriers transported on at least one conveyor. The arrangement includes at least one rotatable deviator positioned to intersect the at least one conveyor. The deviator includes a horizontal deviator plate including at least one grip for receiving a test tube carrier. One contact surface is positioned vertically at a distance from the deviator plate and aligned with the grip. The contact surface is formed to contact the test tube carrier at a distance from the contact level of the grip and the carrier.