UFC 3-280-03
23 JULY 2003
periphery of the filter media used on non-gasketed plates to improve sealing properties
and to better protect the media from the wear and tear of the plate rims repeatedly
hitting and compressing this area. In general, non-gasketed filter designs leak filtrate,
resulting in wet and sometimes malodorous operating conditions. Because of these
conditions, non-gasketed systems are typically equipped with drip trays to collect and
keep the leaking filtrate from the sludge cake storage receptacles or handling
equipment located beneath the filter press.
2-4.5.2.3 In gasketed plate designs, the filter media are typically held in place by
resilient caulking material imbedded in a groove running around and just inside the inner
periphery of the plate rim. Liquid-tight sealing is provided by gaskets, normally O-ring
type, installed in a groove in the sealing faces of the rim and in grooves around the
filtrate ports.
2-4.5.2.4 The primary advantages of gasketed plates as compared with non-gasketed
plates are their ability to keep liquid fully contained in the filter, and their typically longer
media life and lower replacement cost because of the lack of wear in the rim area where
adjacent plates come in contact. However, the disadvantages with gasketed plates are
their slightly higher cost to manufacture, owing to machining of gasketing and caulking
grooves, and the slightly longer time required to change their media.
2-4.5.2.5 Filter press plate construction materials are described further in Subpara-
graph 4-8.1.2. A summary of typical filter press plate sizes and weights is presented in
Table 2-8.
2-4.5.3 Filter Media. Filter media (cloth) are available in several types of materials,
weaves, and permeabilities. Primarily, select the filter media to optimize cake dryness
and filterability of the sludge. Secondarily, durability, ease of cake release, blinding,
chemical resistance, and characteristics of the sludge, such as the size of solids in the
sludge, are important. The durability of the filter media can be affected by both materials
and construction, whereas cake release can be affected by both weave and cleanliness.
In addition to the filter media characteristics, the precoat system (Subparagraph 2-4.6.2)
may be used to ease the release of the sludge cake, or a filter media washing (water or
acid) system (Subparagraph 2-4.6.3) may be used for filter cleaning. The construction
materials, construction factors, and selection of filter media are described in detail in
Subparagraph 2-8.1.1.3.
2-42
Previous Page
