Piping loss's

[cammax]

Just looking for input, I have an engineer telling me of some piping voodoo

We have a higher then normal pressure drop thru an 8" condenser line. calc = 10ft drop while actual drop is 18ft.

One engineer states that due to some tight transitions (ie: close coupled 90 deg elbows that the CV for each fitting in not valid and you cant get an accurate cv for close coupled fittings..... ????

another engineer thinks there may be a blockage in the pipe
at multiple points, as we took readings at many locations down the riser, and found 2 locations with higher loss's

 

[Latexman]

cammax,

If the 90's are connected so the flow is going in a circular or slight spiral pattern, the 90's that follow the first have less dP than the first 90.

If each 90 changes the direction of flow significantly away from circular or a slight spiral pattern, each 90 has the same dP as the first.

Based on this, I'd suspect blockage.

Good luck,
Latexman

 

[KiwiMace]

If the pipe is old, i'd check the roughness allowance in the calculation. Ever seen inside an old condenser pipe? Scale on scale, little stalagtites, nasty stuff.

 

[cammax]

First off Thanks- I’m just trying to digest what I have been told as it contradicts my thoughts.
Brand new pipe, so if you had multiple 90's to make a dbl offset you CAN accurately calculate the loss ?

If anyone would like to see actual data from balancing I will share if anyone wants to ponder it.

 

[BigInch]

Let's see the spool with the data and the data points marked off.

Going the Big Inch!

http://virtualpipeline.spaces.msn.com

 

[Latexman]

cammax,

Take a look at this abstract:

http://nctam2006.fpms.ac.be/preparation_cdrom/Abstract_57_K.Clement_T.Persoons_E.Vandenbulck_KUL.pdf

It was about the closest thing I found (in a short amount of time) using Google and it does speak to dP being dependent on the combination angle of the two close coupled bends.

Good luck,
Latexman

 

[Zapster]

I am unsure what fluid you are talking about when you reference the line as a condenser line. Is this the supply or discharge from your condenser? What is the fluid? Is it possible that you have a different flow regime than your calculations reflect? If it is a discharge line, could part of the fluid stream be flashing around one of then bends?