A resin trap or strainer serves to retain particles in a process flow. The quantity of the particles is in general very low so that cleaning can be done during flow interruption.
A resin trap is normally used to capture expensive resin that escapes from a treatment vessel by accident or to protect equipment further downstream.
A strainer is often used in tubes to block unwanted particles or dirt that would otherwise damage downstream equipment. Cleaning is carried out by removing the strainer from the tube.