# Pressure Drop Through Pipe Calculation

## 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 Swamee-Jain 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 non-circular 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