Reference: Flow of Fluids – Technical Paper No 410, 1988, Crane Co. Appendix B-15.


Pipe Flow Expert File: Case_38_Air_Flow_Through_100ft_Lengths_Of_Steel_Pipes.pfe


Problem Description: 

Compressed air at 100 psi gauge and 60°F flows through 100 feet long schedule 40 steel pipes.

Find the pressure drop in each of the pipes.


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Fluid Data: Air at 100 psi gauge and 60°F, density 0.595574 lb/ft3, viscosity 0.018095 centipoise.

Pipe Data: Internal diameters of standard Schedule 40 Steel pipe, various sizes. Roughness 0.001811 inches.

Calculation Method: General Isothermal Flow equation, Node Adjust Method.

Standard Atmospheric Model: 60 °F, 14.696 psi absolute

Gas Physical Model: Ideal Gas Law


Result Comparison: 


Pipe Details

Free Air ft³/min

Compressed Flow ft³/min

Published Pressure Drop (psi)

Pipe Flow Expert Pressure Drop (psi)

4.0” Diameter Schedule 40 Steel Pipe, 100 ft long

    650

    83.3

0.086

0.0832

6.0” Diameter Schedule 40 Steel Pipe, 100 ft long

14000

1794

4.21

4.2228

8.0” Diameter Schedule 40 Steel Pipe, 100 ft long

16000

2051

1.33

1.3121

10.0” Diameter Schedule 40 Steel Pipe, 100 ft long

24000

3076

0.918

0.9029

12.0” Diameter Schedule 40 Steel Pipe, 100 ft long

28000

3588

0.505

0.4957


Commentary: 

The published data and the calculated results compare well. The density of Air at 100 psi.g and 60°F used in the calculation of the published results was not specified, and the results were based on a non-compressible calculation since the pressure drop was small. 

Pipe Flow Expert’s gas helper calculated the density of the Air at 0.595574 lb/ft3 and used a compressible flow equation to calculate the results.