Page 187 - Standard Handbook Of Petroleum & Natural Gas Engineering

172 General Engineering and Science

CP k 9 Cp/Cv Acoustical
Cas Btu/(lbmole) at 1 atm, pa - velocity at
(OF) 60'F 6O0F,ft/sec
Air. . . . . . . . . 7.00 1.410 0.528 1,031
Helium.. . . . 4.968 1.66 0.486 2,840
Methane.. . . 8.44 1.308 0.545 1,350
Ethane.. . . . 12.30 1.193 0.565 967
Propane.. . . 17.10 1.133 0.577 793
Isobutane. .. 22.4 1.097 0.585 68 1
n-Bucane.. . 23.0 1.094 0.585 680
0.6 gravity. . 8.84 1.299 0.546 1,309
0.7 gravity.. 9.77 1.279 0.550 1,035

Table 2-9
Values of Absolute Roughness,
New, Clean, Commercial Pipes 111

e fr (0.3048 m) x IO6 Mable max
variation off
Type of pipe or rubing Range Design from design. 56
Asphalted ast iron +oo 400 -st0 +I
Bras and copper 5 5 -st0 +5
Concrete 1.ooo 10.000 4.000 -35 to 50
Can iron 850 850 -1otu +IS
Galvanizrd iron 500 SO0 Or0 +IO
Wrought iron 1so I IO -5 to 10
Steel I50 I so -5 to 10
Rivctcd steel 3.000 30.000 6.000 -15 to 7s
Wood stave 600 3.000 2.000 -35 10 20
Campiled fmm &e given in 'Pipe Friction Manual.- Hydnuli Inrrirur. 3d
ed.. 1961.

The Reynolds number is the ratio of the inertia forces acting on the fluid to the
viscous forces acting on the fluid. It is dimensionless and may be calculated as

(2-56)
The term p in Equation 2-56 is the dynamic viscosity of the fluid. The dynamic viscosity
is the ratio of the shear stress to the shear rate. It has units of (force x time)/(area). The
most common unit of viscosity is the centipoise (1 centipoise = 0.01 g/cm - s). Dynamic
viscosity may be a function of temperature, pressure, and shear rate.
For Newtonian fluids the dynamic viscosity is constant (Equation 2-57), for power-
law fluids the dynamic viscosity varies with shear rate (Equation 2-58), and for Bingham
plastic fluids flow occurs only after some minimum shear stress, called the yield stress,
is imposed (Equation 2-59).