(Design) formulae for reducers - contraction angles etc.

[XL83NL]

Does anyone knows of any publication, design info sheet or such (I couldn't find it in any ASME code/standard anywhere),
where I can find the (physical) design, with respect to dimensions and angles, for a (concentric) reducer?

I'm having a hard time defining the K-factor as I don't know several parameters like the exact angle of contraction, etc.
I do know the overall dimensions, and inside radii, but there's more info required for determining the K-factor.
Also, are there any limits as to how fast/sharp the contraction/reduction may occur, or how smoothened it should start?

Thanks in advance.

 

[XL83NL]

Anyone having some suggestions?

 

[ione]

http://www.wermac.org/fittings/dim_reducers.html

 

[ione]

You can use table 7-4 (Loss Coefficients for Expansions and Contractions) chapter 7- page 217 from "Chemical engineering fluid mechanics – second edition , Revised and Expanded" by Ron Darby.

 

[katmar]

There is so much variation between different manaufacturers, and even within the tolerances from one manufacturer, that it is impossible to be accurate with your K-factors. All you can do is choose a conservative average and apply a reasonable safety factor.

For some indication of the variablilty in the real world have a look at

http://rp.ashrae.biz/page/ASHRAE-D-28842-20061024.pdf

Then you can laugh when people argue over whether the K-factor of a fitting is actually 0.26 or 0.28.

Katmar Software - Engineering & Risk Analysis Software

http://katmarsoftware.com

"An undefined problem has an infinite number of solutions"

 

[XL83NL]

Thanks ione, but you first post was already overcome in my original post. I will see if i can find a copy of Darby's book, it may be useful.

Thanks katmar, for the useful link. As you implied, I already thought it's almost impossible to define 'the' K-factor of a fitting. Knowing the range it may operate in at least gives a better engineering approach.