Question

A circular, horizontal tube iwth r = 1 inch and L= 10 ft contains asphalt (? = 70 lbm/ft3 and µ = 67.1 lbm/ft s). A pressure gradient of 10 psi is applied and the asphalt begins to flow. Assuming that asphalt is a Newtonian fluid (which it sometimes is not) calculate the volumetric flow rate of the asphalt leaving the tube. Give your final answer in gpm.

Answer should be 0.58 gpm  

Answer 1

Newtonian fluid obeys Hagen - Poiseuille equation.

R = 1 inch = 0.083 ft
L = 10 ft
= 0.9312 lbm/ft .s
= 10 psi = 1440 lbf/ft²

Q = (1440 x x 0.083⁴) / (8 x 67.1 x 10)
Q = 0.07025 ft³/s

1 ft³/s = 448.83 gpm

Q = 0.07025 x 448.83 = 31.53 gpm

Please check the viscosity value you've given and follow the above procedure.
It happens to be incorrect while comparing with other sources.
The unit of given viscosity is wrong as well.