Friction loss factor

Hard rubber fire hoses are usually provided throughout the process area of a hydrocarbon facility. The coil of a hose on a hose reel presents a considerable friction loss factor to the flow of water through it. In some instances a fire water hose reel may not be completely unrolled from a reel before its use. Therefore it is prudent to conduct a hose reel flow test with a partial removal of the hose and full unreeling from it. The spray reaches of each scenario can then be fully evaluated and observed. 

Correct the friction loss for the liquid consistency. Friction-loss factors are usually plotted for one type of liquid, and correction factors are applied to determine the loss for similar, but different, liquids. Thus, with the Goulds charts, a factor of 0.9 is used for soda, sulfate, bleached sulfite, and reclaimed paper stocks. For ground wood, the factor is 1.40. 

Table 8.5 Friction-Loss Factors for Flow Meters...

Figure 8.17 Friction-loss factors for pipe fittings. From Ref. 19 with permission.

Figure 8.20 Friction-loss factors for tank entrances and exits. From Ref. 18.

Flow in the laminar regime is often characterized by a friction loss factor, which is 64/Re for the Darcy factor or 16/Re for the Fanning factor (this topic wiU be discussed in more details in Chapter 2). As a result, the losses in the laminar regime appear to be a linear function of speed, whereas in the turbulent regime they are proportional to the square of the speed. As we wiU see in Chapter 5, researchers have struggled with special definitions of a modified Reynolds number for non-Newtonian flows. 

Designers often prefer to have a steep launder rather than to suffer a loss of time unblocking settled slurry. As the above equations indicate, the friction loss factor does depend on the hydraulic radius, and larger launders tend to require less slope than small launders. Excessively steep launders tend to lose their liners through fast wear. Obtaining the correct slope without an excessive margin of safety is the correct approach to engineering. 

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