Friction factor roughness values

For smooth pipe, the friction factor is a function only of the Reynolds number. In rough pipe, the relative roughness /D also affects the friction factor. Figure 6-9 plots/as a function of Re and /D. Values of for various materials are given in Table 6-1. The Fanning friction factor should not be confused with the Darcy friction fac tor used by Moody Trans. ASME, 66, 671 [1944]), which is four times greater. Using the momentum equation, the stress at the wall of the pipe may be expressed in terms of the friction factor ... [Pg.636]

For commercial pipe with roughness e = 0.046 mm, the friction factor is about 0.0043. Approaching the last hole, the flow rate, velocity and Reynolds number are about one-tenth their inlet values. At Re = 16,400 the friction factor/is about 0.0070. Using an average value of/ = 0.0057 over the length of the pipe, 4/Z73D is 0.068 and may reasonably be neglected so that Eq. (6-151) may be used. With C, = 0.62,... [Pg.659]

The value of C3 is 0.011454 in USCS units and 20.178 x 10 in SI units. The inputs for the calculation are Q (bbl/hr or mVhr) and pipeline length (miles or km), viscosity U (Centistokes), pipe diameter D (inches or meters), effective pipe roughness e, and pipeline lengths (miles or km). The Fanning friction factor is... [Pg.516]

This is an ultimate case, when the friction factor is no longer a function of the Reynolds number and is a function of roughness the pressure loss is now Ap tv", where w is the fluid velocity in the duct. The surface roughness of typical manufactured ductworks varies between the values of a theoretically fully smooth duct and an artificially roughened one. Accordingly the pressure loss varies between Ap w -w and f =/ (Re, roughness). [Pg.55]

In practice the friction factors are calculated either by integration of Eq. (4.51) or by reference to a Moody chart. This is based on Eq. (4.51) by using equivalent roughness values representing the sand particle roughness (see Table 4.3). [Pg.55]

Scope, 52 Basis, 52 Compressible Flow Vapors and Gases, 54 Factors of Safety for Design Basis, 56 Pipe, Fittings, and Valves, 56 Pipe, 56 Usual Industry Pipe Sizes and Classes Practice, 59 Total Line Pressure Drop, 64 Background Information, 64 Reynolds Number, R,. (Sometimes used Nr ), 67 Friction Factor, f, 68 Pipe—Relative Roughness, 68 Pressure Drop in Fittings, Valves, Connections Incompressible Fluid, 71 Common Denominator for Use of K Factors in a System of Varying Sizes of Internal Dimensions, 72 Validity of K Values,... [Pg.641]

Where f is known the Fanning friction factor which is a function of Re and the roughness of the tube relative to its diameter. For practical systems/ varies from 0.002-0.01. Very little information on local values of t in other geometries. [Pg.296]

Region 4 corresponds to rough pipes at high values of Re. In this region the friction factor becomes independent of Re and depends only on (e/d) as follows ... [Pg.67]

The existence of roughness leads also to decreasing the value of the critical Reynolds number, at which transition from laminar to turbulent flow occurs. The character of the dependence of the friction factor on the Reynolds number in laminar flow remains the same for both smooth and rough micro-channels, i.e., X = const/Re. [Pg.113]

A constant value of the friction factor f = 0.009 is assumed, for fully developed turbulent flow and a relative pipe roughness e = 0.01. The assumed constancy of f, however, depends upon the magnitude of the discharge Reynolds number which is checked during the program. The program also uses the data values given by Szekely and Themelis (1971), but converted to SI. [Pg.498]

Equation (7-25) is implicit for Dec, because the friction factor (/) depends upon Dec through the Reynolds number and the relative roughness of the pipe. It can be solved by iteration in a straightforward manner, however, by the procedure used for the unknown diameter problem in Chapter 6. That is, first assume a value for/ (say, 0.005), calculate Z>ec from Eq. (7-25), and use this diameter to compute the Reynolds number and relative roughness then use these values to find / (from the Moody diagram or Churchill equation). If this value is not the same as the originally assumed value, used it in place of the assumed value and repeat the process until the values of / agree. [Pg.203]

At high Reynolds numbers (high turbulence levels), the flow is dominated by inertial forces and wall roughness, as in pipe flow. The porous medium can be considered an extremely rough conduit, with s/d 1. Thus, the flow at a sufficiently high Reynolds number should be fully turbulent and the friction factor should be constant. This has been confirmed by observations, with the value of the constant equal to approximately 1.75 ... [Pg.395]

The Fanning friction factor/is a function of the Reynolds number Re and the roughness of the pipe e. Table 4-1 provides values of e for various types of clean pipe. Figure 4-7 is a plot of the Fanning friction factor versus Reynolds number with the pipe roughness, eld, as a parameter. For laminar flow the Fanning friction factor is given by... [Pg.122]

Thus the velocity of the liquid discharging from the pipe is 3.66 m/s. The table also shows that the friction factor/changes little with the Reynolds number. Thus we can approximate it using Equation 4-34 for fully developed turbulent flow in rough pipes. Equation 4-34 produces a friction factor value of 0.0041. Then... [Pg.129]

At high Reynolds numbers (Re > 2500), the surface roughness is an important parameter and must be allowed for in the calculations. Friction factor charts [53] include curves relating to various values of the relative roughness, that is the ratio of the mean height of surface roughness to the tube diameter. [Pg.40]

Hints and Help The friction factor, /, calculated from Eq. 24-4 may turn out to be extremely large, which would indicate a very rough riverbed. In fact, in the River Glatt in between the cascades there are small drops every 50 m. Use this fact to explain the rather extreme value of /. ... [Pg.1144]

At higher Reynolds numbers, the friction factor is affected by the roughness of the surface, measured as the ratio e/D of projections on the surface to the diameter of the pipe. Values of e are as follows glass and plastic pipe essentially have e = 0. [Pg.94]

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