Replies to this message

Re: Darcy's Equation
Re: Darcy's Equation -- ABANG1967	Post Reply	Top of thread	Forum

Posted by: mbeychok ® 11/01/2005, 17:42:38 Author Profile Mail author Edit

ABANG1967: The Darcy-Weisbach Equation used in conjuction with the Moody Diagram (for obtaining Fanning friction factors) is considered by many people to be the most reliable method for calculating either frictional pressure loss or frictional head loss for the flow of incompressible fluids in pipes. The Darcy-Weisbach Equation for pressure loss due to friction (in the SI metric system) is: ΔP = 4f(L/D)(ρ v2)/(2 gc) where: ΔP = pressure loss in Pascals f = Fanning friction factor (dimensionless) from Moody's diagram L = pipe length in meters D = pipe diameter in meters ρ = fluid density in kilograms per cubic meter v = fluid velocity in meters per second gc = gravitational conversion constant = 1 (kg-m)/(N-s2) in the SI metric system And for head loss due to friction, the equation is: Δh = f(L/D)(v2)/(2 g) where: Δh = head loss in meters f = friction factor (dimensionless) L = pipe length in meters D = pipe diameter in meters v = fluid velocity in meters per second g = local gravitational acceleration of 9.807 m/s2 Make sure that you are using the Fanning friction factors and not the Darcy friction factors (which are 4 time as large as the Fanning factors). Milton Beychok (Visit me at www.air-dispersion.com) Modified by mbeychok at Wed, Nov 02, 2005, 18:49:06

Post Reply | Recommend | Alert

Where am I? Original Top of thread