| 摘要 |
PROBLEM TO BE SOLVED: To make a great improvement in filter capacity and life in a multiple filter in which plural elements are arranged in parallel. SOLUTION: A multiple filter is constituted of first to nth branch flow passages 21-24 branching off in parallel, first to nth replaceable filter elements 41-44 each arranged in the branch flow passages, first to nth inlet valves 31-34 each arranged on the upstream side of the elements in the branch flow passages and for opening and closing the branch flow passages, first to nth connecting flow passages 25-28 each for connecting the first and the second, the second and the third,..., the nth and the first branch flow passages, and first to nth back pressure valves each for opening and closing the connecting flow passages. And the first to the nth back pressure valves each are opened when differential pressures between the upstream side and the downstream side of the first to the nth elements 41-44 become prescribed values or more. |
