US Patent 11668402 Rotary plug valve with labyrinth

A rotary valve has a valve plug that is rotatable in a valve body about a rotational axis. Surface features of the valve plug and surface features of the valve body cooperate to provide a bearing by which the valve plug is rotatably supported with respect to the valve body. In addition, each of the valve plug and the valve body include a plurality of annular projections that encircle the plain bearing and axially overlap one another so as to form a labyrinth that surrounds the bearing. The labyrinth forms a fluid path that collects abrasive particles suspended in the fluid passing through the valve, whereby wear of the valve is reduced.