Equivalent length of fittings

L(,q = Equivalent length of pipe plus equivalent length of fittings, valves, etc., ft. 

Nominal pipe bore (mm (in)) Equivalent length of fitting ... 

Figure 2-21. Equivalent length of fittings for pipe systems. Note preferred use for VA in. and larger pipe butt-welded or socket-welded connections (this author). By permission, Tube Turns Div., Chemitron Corp. Bull. TT 725,1952, reference now to Tube TUrns Technologies, Inc.

TABLE 2-13 Equivalent Length of Fittings for Friction Loss of Calculations for Single-Phase Turbulent Flow ... 

The flow resistance of pipe fittings (elbows, tees, etc) and valves is expressed in terms of either an equivalent length of straight pipe or velocity head loss (head loss = Kv /2g ). Most handbooks and manufacturers pubHcations dealing with fluid flow incorporate either tables of equivalent lengths for fittings and valves or K values for velocity head loss. Inasmuch as the velocity in the equipment is generally much lower than in the pipe, a pressure loss equal to at least one velocity head occurs when the fluid is accelerated to the pipe velocity. 

Total equivalent length of pipe (assuming that every fitting has an average 5 m of equivalent pipe length, to account for friction) = 1000 + 25 X 5... 

Tlie following table gives equivalent lengths of pipe for various fittings. 

From Figure 2-20 or 2-21 determine the equivalent lengths of all fittings, valves, etc. 

Tabulate the summation of equivalent lengths of straight pipe, valves, fittings, entrance/exit losses as presented in earlier sections of this chapter. 

Some representative figures are given in Table 3.2 for the friction losses in various pipe fittings for mrbulent flow of fluid, and are expressed in terms of the equivalent length of straight pipe with the same resistance, and as the number of velocity heads ( 2/2g) lost. Considerable variation occurs according to the exact construction of the fittings. 

Table 1-1 gives the equivalent length of straight pipe for various fittings (see pp. 10 and 11). 

Number 3 fuel oil (30° API) is transferred from a storage tank at 60°F to a feed tank in a power plant at a rate of 2000 bbl/day. Both tanks are open to the atmosphere, and they are connected by a pipeline containing 1200 ft equivalent length of 1 fin. sch 40 steel pipe and fittings. The level in the feed tank is 20 ft higher than that in the storage tank, and the transfer pump is 60% efficient. 

Equivalent lengths of various valves and fittings are readily available [Holland and Chapman (1966)] and a selection is given in Table 2.3. 

Correlations are available for pressure drops in flowthrough pipe fittings, such as elbows, bends, and valves, and for sudden contractions and enlargements of the pipe diameter as the ratio of equivalent length of straight pipe to its diameter. 

Friction due to fittings, valves and other disturbances of flow in pipe lines is accounted for by the concepts of either their equivalent lengths of pipe or multiples of the velocity head. Accordingly, the pressure drop equation assumes either of the forms... 

These minor fitting losses can also be expressed in terms of an equivalent length of straight horizontal pipe, 4, giving the same frictional loss. 

FIGURE 6.5 Equivalent length of pipe fittings and valves. (Crane Co.)... 

Note that Fig. 6.14 can be used to determine the equivalent length of a variety of pipe fittings. To use Fig. 6.14, simply substitute the appropriate K value in the relation h = Kv2/2g, where h = equivalent length of straight pipe other symbols as before. 

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