Abstract: A filter device for extruders and injection moulding machines designed to process thermoplastics, comprising filter elements that are fitted in at least two separate ducts of a housing between at least one main admission duct and one main exit duct and are interchangeably mounted in sieve carrier bolts in sieve openings that can be moved inwards and outwards with said sieve carrier bolts in the respective bore hole of the housing. At least one locking mechanism is provided in the vicinity of the main admission duct upstream from the sieve carrier bolts. When in a flow position, the locking mechanism does not impede the flow of plastic from the main admission duct to the filter elements.

Abstract: Apparatus for filtering plasticized material between the inlet and the outlet of a housing has two parallel passages for reciprocable filter carriers each of which is movable between a first position and a second position. When in their first positions, the carriers permit plasticized material to flow from the inlet, through filters in their filter chambers and then into the outlet of the housing.

Abstract: Apparatus for filtering a stream of plasticized synthetic plastic material in an extruder has a housing with four or more channels connecting a material-admitting inlet with a material-discharging outlet. The housing is formed with parallel bores each of which receives a single reciprocable cylindrical carrier of two or more filters or two independently reciprocable cylindrical carriers of discrete filters. Each carrier can be moved between a first position in which its filter or filters register with discrete channels of the housing and at least one additional position in which its filter or one of its filters is accessible. At least 75 percent of filtering capacity remains available when a filter is being inspected, cleaned or replaced. The carriers seal those channels which are not in line with filters while the carriers are out of their first positions.