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Line Sizing


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#1 process101

process101

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Posted 22 May 2008 - 10:14 AM

Hello to every one:
Is there any one who can tell me that how to do line sizing by hand. I am using
Pro-max for simulation but I also need to check line sizing by hand,which i never did. So please
if anyone in this Forums can help me out.

Thank you very much for help in advance.

#2 Art Montemayor

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Posted 22 May 2008 - 12:11 PM

Are you saying that you are running a process simulation program and you don't know how to do a pressure drop calculation?

The best thing to do is download the fluid flow articles and other material that is offered for free and others for a price on this Website. Phil Leckner has an excellent article that discusses equivalent lengths versus the 2-K & 3-K methods. Also, obtain a copy of Crane's Technical Paper #410. That will be a start into Fluid Flow and Fluid Mechanics.


#3 djack77494

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Posted 22 May 2008 - 01:21 PM

Crane's TP410 is the closest thing to a "Line Sizing Bible" that there is; you should definitely get yourself a copy.

Theoretically speaking, sizing a line should consist of selecting the optimum size in terms of overall cost. Larger line sizes are good from the viewpoint of less likelihood of erosion due to lower velocity, lower pumping/compression costs due to smaller hydraulic losses, and less noise. Smaller line sizes are good from the viewpoint of lower installed cost, less heat losses, higher velocity limits deposition, less space requirements. In theory at least, all these factors can be translated to net present cost, and to "size" your line, you simply select the size resulting in the lowest net present cost.

Practically speaking, it is not so easy to perform the theoretical calculations. Others have already done them, and, so long as the relative costing does not differ too much from the original values, the previously determined "guidelines" should remain valid. Essentially, the sum total of all considerations is generally distilled down to velocity and/or pressure drop limits. This is inherently sensible because various negative phenomena rapidly become unacceptable beyond the optimum size. Oftentimes, you will find that various factors combine to essentially "pick your line size for you". For example, in an existing system you may have a fixed differential pressure available and you must size the line to fit your hydraulic constraints. Slurry lines may have a narrow range between saltation velocities and the velocity where erosion becomes excessive, and so their size may be essentially fixed. Other times your company's technical manuals will guide you to selecting a line size based on a maximum velocity (most common) or pressure losses (less common).




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