E4.9 Pressure Drop, Velocity Unknown Case

Example 4.9: Pressure drop through a galvanized iron pipe is 100 psi. Inside diameter of the pipe is 1.38 in. Equivalent length of the pipe is 2000 ft. Determine the velocity of the fluid if the following information applies:

Viscosity of water = 7.556 ´ 10^-4 lb/(ft·s); density of water = 62.36 lb/ft³

Roughness of the pipe = 0.0005 ft.

Assume that pipe is horizontal and entrance and exit losses are negligible.

Solution

Pressure drop, ΔP = 1440 lb_f/ft²

Frictional losses (h_f):

Group ReÖf (Equation 4.16):

Friction factor, f (Figure 4.4) = 0.0078.

Reynold number, Re (Figure 4.3) = 4.98 ´ 10⁴.

Velocity of the fluid, V (Equation 4.12):