Method for operating a filter device and filter device

A filter device, comprising:

• a first filter chamber in which a first large area filter is located, and a second filter chamber in which a second large area filter is located, a first inlet with a first inlet valve to the first filter chamber, a second inlet with a second inlet valve to the second filter chamber, a first drain from the first filter chamber, a second drain from the second filter chamber,
• a first drain valve in the first drain, a second drain valve in the second drain, wherein the inlet valves and the drain valves are designed to be hydraulically and/or electrically actuated, that a control device is provided which controls the inlet valves and the drain valves for setting the basic and backflushing modes of operation, respectively, the filter device carrying out a method wherein a polymer melt to be filtered is conveyed under pressure through the filter device, wherein the first inlet and the second inlet are connected to a common inlet and the first drain and the second drain are connected to a common drain, polymer melt to be filtered is simultaneously fed to both the first large-area filter and the second large-area filter in the filter direction, and parallel filtering is continuously performed via the first and second large-area filters in a basic mode of operation, and merely filtering in a backflushing mode of operation is performed via only one large-area filter, which backflushing mode of operation is started when the large-area filter has reached a predefined degree of contamination the first large-area filter is cleaned using a backflushing operation.