The utility model discloses a preposed filtering device applied to an N-methyl pyrrolidone circulating pipeline in the field of
wet cleaning, which comprises a
barrel body and a cover body detachably arranged at the top of the
barrel body, a containing cavity with an opening at the top is arranged in the
barrel body, the size of the containing cavity is gradually reduced along the vertical direction, and the cover body is arranged in the containing cavity. A containing cavity is formed in the cover body, at least two horizontal ladder surfaces are formed in the inner wall of the containing cavity in the vertical direction, at least two filter screens different in size are installed in the containing cavity and fixed through the horizontal ladder surfaces at the corresponding positions, and a
glass sheet which can be seen into the containing cavity is installed in the middle of the cover body. Three filter screens with different sizes are arranged in the big-end-up accommodating cavity for filtering in sequence, so that the filtering effect is improved, and the organic
medicine liquid is prevented from staying in the accommodating cavity; the filter screen is fixed through the horizontal ladder surface on the inner wall of the accommodating cavity, so that the filter screen is convenient to
mount and dismount; and the cover body is provided with the
glass sheet for directly viewing the interior of the accommodating cavity, so that the accumulation condition of
photoresist and a film layer on the filter screen can be conveniently observed, and timely cleaning is realized.