A Y-strainer is a type of mechanical strainer or filter used in piping systems to remove unwanted solid particles from flowing liquids. It consists of a housing shaped like the letter "Y" with a screen or perforated mesh inside, forming a filtering element. In operation, the Y-strainer is installed in a pipeline, typically in a horizontal position, with the flow direction entering through the inlet at the top of the Y and exiting through the outlet at the bottom. As the liquid flows through the strainer, solid particles and debris are trapped by the screen or mesh, while the filtered liquid continues downstream.