Darcy - Weisbach Pressure Drop Per Mile

Darcy-Weisbach equations are valid for steady state flow. The friction factor – λ -depends on the flow, (laminar, transient, turbulent, Reynolds number) and the internal roughness of the pipe. The friction coefficient can be calculated by the Colebrook-White equation.
Limitations of this calculation depend on the flow regime for the right friction factor or coefficient.
Many factors affect the head loss in pipes, the viscosity of the fluid being handled, the size of the pipes, the roughness of the internal surface of the pipes, the changes in elevations within the system and the length of travel of the fluid.

𝐻_𝐿 − Head Loss [ft]

f – Friction Factor

𝐿 − Pipe Length [ft]

𝐷 − Internal Pipe Diameter [in]

𝑣 − Flowing Velocity [ft/sec]

𝑔 − Gravitational Constant [ft²/sec]

 
Friction factor is solved using Newton-Raphson method.

𝑓 − Friction Factor

D – Inside Pipe Diameter[in]

𝜀 − Pipe Roughness[in]

 

Where:

∆𝜌 − Pressure Loss [psi]

𝜆 – Darcy-Weisbach Fiction Coefficient

𝐿 − Pipe Length [ft]

𝐷_ℎ − Hydraulic Diameter [in]

𝑣 − Velocity [ft/sec]

𝜌 − density [lb/ft²]

 

Input Parameters

1. To create a new case, click the “Add Case” button
2. Select the Darcy-Weisbach – Pressure Drop per Mile application from the Hydraulics module.
3. Enter Case Name, Location, Date and any necessary notes.
4. Fill out all required fields.
5. Make sure the values you are inputting are in the correct units.
6. Click the CALCULATE button.

• Pipe Type
• Pipe Outside Diameter
• Pipe Wall Thickness
• Flowing Temperature (°F)
• Absolute Pipe Roughness
• Specific Gravity
• Flow Rate (MCFD)
• Internal Pipe Diameter(in)
• Kinematic Viscosity
• Length of Pipeline(mi)
• Upstream Elevation(ft)
• Downstream Elevation(ft)

Pressure Drop per Mile

 

 

Outputs/Reports

1. View the results.
2. If an input parameter needs to be edited be sure to hit the CALCULATE button after the change.
3. To SAVE, fill out all required case details then click the SAVE button.
4. To rename an existing file, click the SAVE As button. Provide all case info then click SAVE.
5. To generate a REPORT, click the REPORT button.
6. The user may export the Case/Report by clicking the Export to Excel/PowerPoint icon.
7. To delete a case, click the DELETE icon near the top of the widget.

• Friction Factor
• Heal Loss (ft)
• Pressure Drop (psi/mi)
• Average Velocity (ft/sec)
• Erosional Velocity (ft/sec.)
• Sonic Velocity (ft/sec.)

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