Pressure drop equation & resistance coefficient values for fittings

[Ima1]

Hi,
I would like someone to help me confirm the Darcy-Weisbach pressure drop equation based on liquid flowrate. I would also like a reference to or scanned copy of resistance coefficients for fittings particularly reducers and y-type strainers.

 

[TD2K]

For Y type strainers you really should get this from the vendor since the strainer mesh and the open area is a key factor in how much pressure drop you will take.

For the reducers, do you have any engineers around with a copy of Crane? They have formulas in there to calculate the resistance coefficient of fittings. I have not seen tabulated values of these and frankly, the dP across a reducer is usually insignificant compared to the entire piping system.

 

[Ima1]

TD2K, Thanks for the tip.

 

[25362]

http://www.mcnallyinstitute.com/CDweb/graphics/gr025.htm

 

[LHA]

Darcy-Weisbach pressure drop equation:

delta p = f * L * v^2 * density / (2 * D * g) = headloss * density

Remember: The Chinese ideogram for “crisis” is comprised of the characters for “danger” and “opportunity.”
-Steve

 

[jmw]

I think one of the links (above) will take you to Crane who publish an excellent reference available in metric or imperial: "Flow of Fluids" (Through valves fittings and pipe)

http://www.craneco.com/flow_fluids.cfm

Mine is the 7th printing and has Darcy but i didn't find Darcy -weisbach... it may be in later editions?

JMW

http://www.ViscoAnalyser.com

 

[Montemayor]

Ima1:

The Darcy-Weisbach equation is the classical expression for the pressure drop of a liquid fluid through a hydraulic system. It is the one explained and employed in the Crane TP #410. The "Darcy" equation is a totally different beast.

You would waste your time in "confirming" the veracity of the Darcy-Weisbach equation. This has been done countless times and is an accepted fact for well over 75 years. Glenn Brown at Oklahoma State U has an excellent website dedicated to Henry Darcy:

biosystems.okstate.edu/darcy/DarcyWeisbach/ Darcy-WeisbachEq.htm

You might enjoy reading his explanations.