Pressure Drop Through Pipe Calculation
 Darcy–Weisbach equation is an empirical equation to determine the head loss, or pressure loss, due to friction for a given length of pipe to the average velocity of the fluid flow for an incompressible fluid
 This formula is directly proportional to the square of the average velocity
Steps to determine the Pressure Drop through the duct
 Known Quantities:
 Density of the fluid, ρ
 Dynamic viscosity of the fluid, μ
 Hydraulic diameter of the duct, D = 2* a* b / (a + b)
 Average fluid velocity, ⟨v⟩
 Determine Reynolds Number: Re = ρ*⟨v⟩* D/μ
 Laminar flow: Re < 2100
 Turbulent Flow: Re > 4000
 Determine the friction factors (Fd) as a function of friction factor and Reynolds number
 Refer to the fluid Mechanics books to get different correlations for friction factor

 Commonly used the SwameeJain Equation for turbulent flow
 Determine Pressure drop per unit length of pipe (ΔP/L) in wg/ft
Pressure Drop Calculator
 Enter values in the column
 For hydraulic diameter:
 Enter the sectional sizes (a x b) for noncircular ducts
 Enter a diameter (D) directly for circular pipe
 Understand the type of flow: laminar or turbulent, however, the turbulent formula has been used
 Note SI or Imperial units