a backwashable filtering device for thermoplastic plastics material is disclosed . the device can filter thermoplastic plastics material through one or more nests of screens in the filtering position , while submitting some nests of screens to the backwashing process that cleans them . the filtering position and the backwashing position are selectable by displacing one or more carrying bodies with respect to a housing and / or by displacing one or more control bodies with respect to the carrying bodies . the backwashing can be performed over an entire nest of screens or over a portion of a nest of screens . the nests of screens can be straight or curved .