This self-centering device for cylindrical elements such as filters, coalescers and separators having a central axis and adapted for placement with an open end over and in communication with an aperture with a rod extending from its center incorporates or includes a notched member having an open side adapted for lateral capture of the rod along with a holding structure for holding the notched member in position proximate the central axis. The holding structure includes a connector for connection of the self-centering element to the cylindrical element, and a dividing member adapted to divide the open end of the cylindrical element into portions in communication with the open side and portions not in communication with the open side. The connector can advantageously take the form of a member attached to the cylindrical element proximate the open end, a member attached to a rim of the cylindrical element proximate said open end, and/or a member forming a portion of the rim attached to the cylindrical element proximate said open end.