Abstract: Filtration apparatuses for use in polymer processing systems and methods of using the same are provided. The filtration apparatuses can include a housing with one or more supply channels and discharge channels. The filtration apparatus can also include one or more screen-bearing pistons with filter screen cavities therein for receiving filter screens that filter material flowing from the supply channels through the filter screens and out through the discharge channels. Back flushing channels can be formed by alignment of mating channels in the pistons and the housing. The filtration apparatuses can also include a controller that can communicate with a hydraulic power unit to that can be assisted by a rapid accelerator device to control the filtration apparatus. The filtration apparatuses can include filter screen retention plates.