A pipe reducer changes the size of the pipe. There are two types of reducer used in piping Concentric & Eccentric.
Concentric Pipe Reducer or Conical Reducer
In Concentric reducer which is also known as a conical reducer, the center of both the ends is on the same axis. It maintains the centerline elevation of the pipeline. When the center lines of the larger pipe and smaller pipe are to be maintained same, then concentric reducers are used.