Pressure Loss

Pressure loss. Smooth horizontal pipe. 4000 ≤ Re ≤ 105  
Flow Rate, Q (m3/s): 
Pipe Inside Diameter, D (m): 
Pipe Length, L (m): 
Density, ρ (kg/m3): 
Dynamic Viscosity, μ (N-s/m2): 
Pressure Loss, P1-P2 (N/m2): 
Velocity, V(m/s): 
Reynolds Number, Re: 
Moody friction factor, f: 

Pressure Loss Diagram

Pressure loss diagram

Pressure Loss Equations

For steady flow of an incompressible fluid in a constant diameter horizontal pipe using the Darcy-Weisbach friction loss equation, the energy equation for flow from location 1 to 2 is expressed in terms of pressure loss as:

Pressure loss equation


Area, velocity for pressure loss derivation      Reynolds number for pressure loss derivation

For pressure loss, the Blasius equation represents the Moody friction factor for smooth pipes and 4000 ≤ Re ≤ 105 (Streeter et al., 1998, p. 291):

Pressure loss derivation - Moody friction factor

Pressure loss unit abbreviations, symbols: kg=kilogram, m=meter, N=Newton, s=second. A=Pipe area.

Reference for pressure loss: Streeter, V. L., Wylie, E. B, and Bedford, K. W. 1998. Fluid Mechanics. WCB/McGraw-Hill. 3ed.


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