A filtering device includes a hollow casing and a plurality of tubes. The casing includes an interior defined by a surrounding wall. The casing further includes a plurality of through-holes defined in the surrounding wall and in communication with the interior of the casing. Each tube extends through an associated one of the through-holes of the casing into the interior of the casing. In another embodiment, a filtering device includes a first hollow casing and a second hollow casing received in the first hollow casing. Each of the first hollow casing and the second hollow casing includes an interior delimited by a surrounding wall. A plurality of through-holes are defined in each of the surrounding walls of the first hollow casing and the second hollow casing.