Valve unit caged

Figures 6.3 and 6.4 show different types of valve trays and valve units. Valves can be round or rectangular, with or without a caging structure. A detailed description is available elsewhere (1), and in manufacturers literature (7-9). The valve disks rise as vapor rate is increased (Fig. 6.2c), The upper limit of opening is controlled by a caging structure or by restrictive legs at the bottom of the valve unit. As vapor rate falls, the disk openings are reduced, or they may settle intermittently over the holes. This stops the liquid from...

Figure 6.4 Types of valve units, (a) An uncaged, mind valve unit. (6) A caged, round valve unit, (c) A caged, round valve unit featuring contoured orifice, fd) A rectangular valve unit it) A futed, round valve unit, if) A fixed, triangular v hre unit, (forts a and e courtesy of Gtiisch Inej parts b, c and f courtesy of Koch Engineering Company, Inc. pari d courtesy of Nutter Engineering.)...

Hea.rt Va.Ives. Since the early 1960s nearly 50 different heart valves have been developed. The most commonly used valves as of the mid-1990s include mechanical prostheses and tissue valves. Nearly 75,000 of these prosthetic valves are implanted aimually worldwide, and about 30,000 in the United States alone. Caged-baH, caged disk, and til ting-disk heart valves are the types most widely used. 

Currently, about 90,000 valve replacement procedures are conducted in the United States, with about 280,000 such procedures conducted around the world [13]. The world population is expected to increase from 6.1 billion in 2000 to 8.9 billion in 2050, with the percentage of people of the population over 65 years increasing from 6.9% of the world population in 2000 to 15.9% in 2050 [14]. This aging population of patients requiring heart valve replacement is estimated to triple by 2050, from -290,000 in 2003, to over 850,000 by 2050 [15,16]. The most commonly used valve replacements in the developed world are mechanical bileaflet valves and bioprosthetic valves. In developing countries, tilting disk and ball-and-cage valves continue to be used due to lower costs. Across all valves, aortic valves are most widely replaced, followed by the mitral valve, pulmonary valve, and tricuspid valve. 

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