Click here to enlarge imageThe filtration bed of the Fuzzy Filter is composed of a multitude of roughly spherical balls of synthetic fibers. These fibers are bound together at the center of each ball by a metal binder clip. Each sphere, in its uncompressed state, is about 1.25 inches in diameter. This compressible media, with a porosity of 88% to 90%, has a density that makes it just slightly heavier than water and produces an uncompressed filter bed that exhibits a porosity of roughly 92% to 94%.
The test setup for the compression gradient study is shown in Figure 1. As can be seen in the figure, the vessel was constructed of a transparent high impact plastic to allow total visibility during the study.
The transparent portion of the test vessel was 60" in height and was bounded on the lower end by a perforated plate, which was fixed in place. A vertically moveable perforated plate, used to compress the bed, served as the upper limit.
An actuator mounted on top of the vessel controlled the position of the upper moveable plate and supplied the compressing force. Also, evident in Figure 1, are the five rigid plastic sectional spacers used to create six identifiable sections of the media bed.
Prior to compression, the position of each of the sectional spacers relative to the lower plate was recorded as the “base” or “uncompressed position”. The testing procedures involved compressing the media bed, measuring the overall compression of the filter bed, and then measuring the change in the distances between the sectional spacers. From this raw data, the percentage of compression for each of the individual sections of the media bed was computed and related to the overall change in compression for the entire media bed.
The results of one run of these compression tests are recorded in Table 1. The compression levels of 19%, 37% and 50% that were imposed on the overall media bed are shown as columns in Table 1.
A compression gradient was determined to exist with the top section being compressed roughly twice as much as the bottom section. For example, in Table 1, at an overall compression of 50%, the top section experienced a compression of 60.5% while the bottom section was only compressed by 33.8% Such results are logical, since the media bed was compressed from the top down.
Conclusions
The evidence from the study provides documented proof of the existence of the theorized compression gradient described at the outset. The study strongly supports the existence of a compression gradient across the filter bed as opposed to a uniform compression throughout the filter bed. Every compression test performed during the study produced a compression gradient across the filter bed similar to that recorded in Table 1.
Additionally, the evidence from the study showed that the direction of the compression gradient was consistent. The greatest compression always occurred at the top of the filter bed, nearest the compressing upper moveable plate. Conversely, the least compression constantly appeared at the bottom of the filter bed - farthest from the upper moveable plate.
