Pipe Reducer Head Loss Equation

[dmarquis]

Hi All:
Can someone help me find the reference/source of this equation? It's for calculating the head loss through a reducer. It was posted by BigInch in 2006.

Hf_Temp = (1 / CC - 1) ^ 2 * V2 ^ 2 / (2 * g_SI)
where
CC = 0.582 + 0.418 / (1 - D2 / D1)

It seems to work, but I need the reference before I can confidently use it in my calculations.

Thanks

 

[pipesnpumps]

maybe Crane 410 manual

Real world knowledge doesn't fall out of the sky on a parachute, but rather is gained in small increments during moments of panic or curiosity.

 

[dmarquis]

Finally, got a copy of Crane 410 and while it does have an equation of the resistant coefficient, it does not actually have an equation for the equivalent length

Any other ideas?

It was interesting though that this equation does not consider the quickness of the reduction/enlargement; i.e. the included angle. I know that in general, pipes have consistent reduction/expansion rates, but having the full story would be great as a teaching tool too.

Thanks

 

[katmar]

I do not recognize the equation you posted, but the equation which I generally use for reducers (in the contraction mode) also does not include the taper angle or fitting length. This equation comes from the article "Calculate head loss caused by change in pipe size" by William B. Hooper in Chem Eng, Nov 7, 1988, pgs 89-92.

Hooper's equation is K₁ = [0.1 + 50/Re₁][ (D₁/D₂)⁴ - 1]

where subscript 1 is for upstream and 2 for downstream.

Hooper implies that provided the corners of the reducer are well rounded the length is unimportant. Hooper pointed out that very little published data was available at the time. The data (published after Hooper's article) I referenced in thread378-307284 indicates that Hooper's numbers may be a little bit optimistic, but there is a large spread in the available data so it is hard to say who is accurate.

Crane, and basically every other book that talks about reducers, gives data for straight sided conical reducers which I have seen only very rarely out in the field. It seems that conical reducers are only used by instrument engineers when installing a control valve smaller than the line size and where they want a minimum of pressure drop in the reducers. But I suspect it is more for historical reasons than good engineering. (Ducks and runs for cover as control engineers attack)

Katmar Software - Engineering & Risk Analysis Software

http://katmarsoftware.com

"An undefined problem has an infinite number of solutions"

 

[BigInch]

I think that would be the
Piping Design Handbook
McKetta & Dekker 1992

Only put off until tomorrow what you are willing to die having left undone. - Pablo Picasso

 

[psafety]

Cameron Hydraulic Data also has it.

 

[dmarquis]

Sweet. Thanks to all.