Caged valve

Figure 6.5 Valve trays, (a) A valve tray equipped with round uncaged valves (b) a valve tray equipped with round caged valves (c) a valve tray equipped with rectangular valves (d) a valve tray containing both round uncaged valves and perforations.CParts a and d courtesy of Koch Engineering Company, Inc. part b courtesy of of Glitsch Inc. part c courtesy of Nutter Engineering.)...

Introduction of the Starr-Edwards ball-and-cage valve... 

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. 

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. 

The plug, cage, seat ring, and associated seals are laiovvn as the trim, A kev feature of globe valves is that thev allow maintenance of the trim via a removable bonnet without removing the valve bodv from the line. Bonnets are tvpicallv bolted on but rnav be threaded in smaller sizes. 

The valve plates, discs, and springs are mounted in a valve cage, which is inserted in the cylinder. Valve breakage occurs due to fatigue of the metal or improper action. This requires replacement and an evaluation of the materials of construction as well as the basic type of valve. Each manufecturer presents his valve design to match his equipment. Only experience can determine which type of valve works best in a given application... 

Imperial Chemical Industries has introduced a new crystalline poly(ether ether ketone) (PEEK) (structure 4.78). Applications are for compressor plates, valve seats, thrust washers, bearing cages, and pump impellers. In the aerospace industry it is employed as aircraft fairing, fuel valves, and ducting. It is also used in the electrical industry as wire coating and semiconductor wafer carriers. 

Pump. Solution is pumped at low flow rate through the cell by means of a Lapp Pulsafeeder pump Model LS-10. Difficulty in maintaining constant flow at slow flow rates was traced to small air pockets in the diaphragm pump head that would not spontaneously pass the exit check valve. This difficulty was remedied by the aspiration of the feed solution to remove dissolved gases. To minimize the hazard of implosion of the feed reservoir, a cage was made from 1/4-inch hardware cloth to fit the 20-liter reservoir. 

Moving valve trays (Fig. 14-18c) have the perforations covered by movable disks (valves). Each valve rises as the gas velocity increases. The upper limit of the rise is controlled by restricting legs on the bottom of the valve (Fig. 14-18c) or by a cage structure around the valve. As the gas velocity falls, some valves close com-... 

FIG. 8-67 Cage-guided balanced plug globe valve with polymer seat and plug seal. (Courtesy Fisher Controls International LLC.)... 

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