Twilled Square meshes

Grootenhuis (Proc. Inst. Mech. Eng. [London], A168, 837—846 [1954]) presents data which indicate that for a series of screens, the total pressure drop equals the number of screens times the pressure drop for one screen, and is not affected by the spacing between screens or their orientation with respect to one another, and presents a correlation for frictional losses across plain square-mesh screens and sintered gauzes. Armour and Cannon (AIChE J., 14,415-420 [1968]) give a correlation based on a packed bed model for plain, twill, and dutch weaves. For losses through monofilament fabrics see Pedersen (Filtr. Sep., 11, 586-589 [1975]). For screens Inclined at an angle 0, use the normal velocity component V ... 

There are a number of different filter materials. Wire screens are the most common. Several t5 es of wire screens are available, such as the square mesh with plain weave and the square mesh with Dutch twill. There are also depth filtration media, such as sintered metal powder and random metal fibers. Advantages and disadvantages of different filter materials are shown in Table 1. 

FIGURE 13.1 Model Predicted Liquid Hydrogen Bubble Point Pressure Over the Anticipated Operating Range of a Cryogenic Fuel Depot for (a) Five Finest Dutch Twill, (b) Coarse Dutch Twill and Plain Dutch, and (c) Twilled and Plain Square Mesh Screens. All curves assume GHe pressurant and Tgas=Tuquid-... 

There are three important types of metallic filter medium wire mesh, sintered powder, and random fiber. Wire mesh comes in a square weave or Dutch twill (woven in parallel diagonal lines). The different filter media do not perform equally with respect to their ability to hold contaminant, capture gels, etc. [11, 12]. A relative performance comparison is shown in Table 3.7. 

Wire mesh, square weave Wire mesh, Dutch twill Sintered powder Random metal fiber... 

Wire mesh square weave Wire mesh Dutch twill Sintered metal powder Random metal fibers... 

Figure 4.17 shows a sample of the wicking distance as a function of time for the three fine mesh Dutch Twill samples. As shown, the wicking distance is proportional to the square root of time, as predicted by Equation (3.65). The fastest wicking distance occurs with the coarsest screen, consistent with historical trends. 

Filtration is accomplished with wire mesh screens (square or twill weave), sintered powder, or sintered metal fibers. Table 12.5 shows a comparison of the various filtration media and their characteristics. Square weave screen. Fig. 12.50, has every other wire... 

---