We stress that table 65 represents losses averaged

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Unformatted text preview: 5 only serving as a rough guide. The valve losses in Table 6.5 are for the fully open condition. Losses can be much higher for a partially open valve. Figure 6.18b gives average losses for three valves as a function of “percentage open,” as defined by the opening-distance ratio h/D (see Fig. 6.17 for the geometries). Again we should warn of a possible uncertainty of 50 percent. Of all minor losses, valves, because of their complex geometry, are most sensitive to manufacturers’ design details. For more accuracy, the particular design and manufacturer should be consulted [35]. 0.34 Legend Plastic elbow Metal elbow no. 1 Metal elbow no. 2 0.32 10% 0.30 K factor 0.28 Curve-fit correlation K 1.49 Re 0.145 0.26 10% 0.24 0.22 0.20 0.18 | v v Fig. 6.18a Recent measured loss coefficients for 90° elbows. These values are less than those reported in Table 6.5. [From Ref. 48, courtesy of R. D. Coffield.] | 0.16 0.05 e-Text Main Menu 0.1 0.2 0.3 0.5 1.0 2.0 3.0 4.0 Reynolds number (millions) | Textbook Table of Contents | Stud...
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This note was uploaded on 10/27/2009 for the course MAE 101a taught by Professor Sakar during the Spring '08 term at UCSD.

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