摘要 |
A multistage filter unit comprises a housing having a closed end and an other end closed except for liquid inlet means and liquid outlet means. Within the housing are first and second filter elements. The improvement is characterized by the second filter element being comprised of a porous disc retained in or adjacent the opening of the first filter element by a foraminous element. The porous disc is deformable in response to increase in differential pressure due to clogging of the porous disc to reduce the liquid flow path through the porous disc and relieve some of the differential pressure, without opening an unfiltered path for liquid.
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