Gradual contractions in pipe
Gradual contractions in pipe
(OP)
Hello,
I am looking at page A-26 in Crane's manual. It shows that for pipe with a gradual contraction with an angle of convergence of between 45 and 180, we are to use Formula 4.
Formula 4 is dependant on the sine of half the angle.
If I use an angle of 180 (abrupt change in diameter) then should this correlation not be equal to Equation 2-10 on page 2-11???
This does not make sense, since Formula 4 is divided by Beta ^ 4, there can't be legitimacy here?? They must equal if the wall angle = 180!!
Please explain this to me.
Thank you.
I am looking at page A-26 in Crane's manual. It shows that for pipe with a gradual contraction with an angle of convergence of between 45 and 180, we are to use Formula 4.
Formula 4 is dependant on the sine of half the angle.
If I use an angle of 180 (abrupt change in diameter) then should this correlation not be equal to Equation 2-10 on page 2-11???
This does not make sense, since Formula 4 is divided by Beta ^ 4, there can't be legitimacy here?? They must equal if the wall angle = 180!!
Please explain this to me.
Thank you.





RE: Gradual contractions in pipe
√(sin(180/2)) = √(sin(90)) = √1 = 1
Equation 2-10 gives the value for K1, which is based on the smaller pipe diameter. Formula 2 gives the value for K2, which is based on the larger diameter. K1 and K2 are related by equations 2-5 and 2-11.
Katmar Software
Engineering & Risk Analysis Software
http://katmarsoftware.com
RE: Gradual contractions in pipe
Or is 1/B^4 just a factor that need not be considered when comparing the two equations?
Thanks katmar
RE: Gradual contractions in pipe
Yes. Formula 2 is Equation 2-10 (Κ1) divided by Β4; that's what the second "=" is telling you.
Yes. You need to consider the Β4 when comparing the two equations. Κ1 ≠ Κ2.
As katmar stated, it's because Equation 2-10 is in terms of Κ1, while Formula 2 is in terms of Κ2. (Actually this applies to all the formulas on page A-26)
Patricia Lougheed
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RE: Gradual contractions in pipe
Makes sense now.