The present disclosure relates to a rotatable tube rack holder for a tube rack rotator device, comprising: one or more plate(s) extending radially from an axis of rotation; one or more compartment(s) for tightly holding one or more tube rack(s) configured to hold a plurality of tubes, said compartment(s) is/are attached to at least one side of said plate(s); and one locking mechanism for each of said compartment and configured such that when said tube rack(s) holding a plurality of said tubes is/are placed inside said compartment, said tubes are restricted from moving in a direction perpendicular to said plate.