Woven fabrics, flow through

Pulse-jet filters are commonly used for both dusts and fumes. These filters have the gas flow from outside to inside through internally supported bags of felted rather than woven fabric. Dust is deposited on the outside of the bag. The... 

Filter elements may be divided into two classes surface and depth. Surface filters are made of closely woven fabric or treated paper with a uniform pore size. Fluid flows through the pores of the filter material and contaminants are stropped on the filter s surface. This type of filter element is designed to prevent the passage of a high percentage of solids of a specific size. 

Two principal types of fabric are adaptable to filter use woven fabrics, which are used in shaker and reverse-flow filters and felts, which are used in reverse-pulse filters. The felts made from synthetic fibers are needle felts (i.e., felted on a needle loom) and are normally reinforced with a woven insert. The physical properties and air permeabilities of some typical woven and felt filter fabrics are presented in Tables 17-6 and 17-7. The air permeability of a filter fabric is defined as the flow rate of air in cubic feet per minute (at 70°F, 1 atm) that will pass through 1 ft2 of clean fabric under an applied differential pressure of Vt in water. The resistance coefficient KF of the clean fabric is defined by the equation in Table 17-6, which may be used to calculate the value of KF from the air permeability. If Ap, is taken as 0.5 in water, t as 0.0181 cP (the viscosity of air at 70°F and 1 atm), and Vj as the air permeability, then //, = 27.8/air permeability. 

In a filter, the dusty gases are passed through a filter medium, which retains the particles to the extent provided by the medium chosen. Media include sand gravel beds natural, synthetic, or glass fiber woven mats woven fabrics or felts. The most cotmnon are woven fabrics, which are cleaned by shaking, intermittent reverse flow, continuous reverse flow, or air pulses. 

The Cook Zenith AAA endovascular graft was approved for use by the FDA in May 2003 (FDA 2013). It contains three different components the main graft module, the contralateral limb module, and the ipsilateral iliac extension (Fig. 21.12). All of these are constructed with a full-thickness woven polyester fabric attached to self-expanding stainless steel Cook-Z stents with braided polyester and monofilament polypropylene sutures. The distal end of the main body has a bare stainless steel stent designed to allow suprarenal fixation without disrupting blood flow through the renal arteries (Fig. 21.13). The stent also has hooks on each strut spaced 3 mm apart that are intended to dig into the aortic wall and prevent migration (Fig. 21.13). The proximal covered stent, located just below the bare suprarenal stent. 

Turan R B and Okur A (2013), Prediction of the in-plane and through-plane fluid flow behavior of woven fabrics . Text Res J, 83(7), 700-717. 

Amico, S. and Lekakou, C., Mathematical modeling of capillary micro-flow through woven fabrics . Composites Part A Applied Science and Manufacturing, 31(12), 1331-1344, 2000. 

ODC d, made of silver and PTFE (Bayer Material Science AG, BMS), within the so-called percolator c, a woven fabric which adjusts the flow rate of caustic soda solution. The ODC d and the cathodic current distributor f are electrically connected on their entire area by the elastic element e, made of fine, interwoven nickel wire. This elastic element e presses the ODC d, the percolator c, and the membrane b with optimized pressure onto the anode a. Therefore, the usual anode half shell of the conventional membrane process, completely filled with anolyte, can be apphed, and no falling film construction is necessary on the anode side as it is used in [10]. The percolator c withstands the pressure of the elastic element e and remains sufficiently permeable for the catholyte flow. Free oxygen gas transport into the ODC d is possible through the elastic element e. 

As an example of the application of the above analysis for flow through packed beds of particles, we will briefly consider cake filtration. Cake filtration is widely used in industry to separate solid particles from suspension in liquid. It involves the build up of a bed or cake of particles on a porous surface known as the filter medium, which commonly takes the form of a woven fabric. In cake filtration the pore size of the medium is less than the size of the particles to be filtered. It will be appreciated that this filtration process can be analysed in terms of the flow of fluid through a packed bed of particles, the depth of which is increasing with time. In practice the voidage of the cake may also change with time. However, we will first consider the case where the cake voidage is constant, i.e. an incompressible cake. 

---