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Unformatted text preview: sistent with the higher Reynolds number and decreased roughness ratio of large pipes. We stress that Table 6.5 represents losses averaged among various manufacturers, so there is an uncertainty as high as 50 percent. In addition, most of the data in Table 6.5 are relatively old [15, 16] and therefore based upon fittings manufactured in the 1950s. Modern forged and molded fittings may yield somewhat different loss factors, often less than listed in Table 6.5. An example, shown in Fig. 6.18a, gives very recent data [48] for fairly short (bend-radius/elbowdiameter 1.2) flanged 90° elbows. The elbow diameter was 1.69 in. Notice first that K is plotted versus Reynolds number, rather than versus the raw (dimensional) pipe diameters in Table 6.5, and therefore Fig. 6.18a has more generality. Then notice that the K values of 0.23 0.05 are significantly less than the values for 90° elbows in Table 6.5, indicating smoother walls and/or better design. One may conclude that (1) Table 6.5 data are probably conservative and (2) loss factors are highly dependent upon actual design and manufacturing factors, with Table 6....
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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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