Basic formula to calculate pressure drop
Basic formula to calculate pressure drop
(OP)
Hi Experts,
Just got a task to do some calculation about our hydraulic control system. I have enough education to understand the dynamics, etc but almost never worked on such real problems.
Spent tody online and already got some ideas about how to calculate pressure drop in pipes. But need to know more cause our system got a lot of components such 90 or 45 deg elblows, branch and running tees, enlarger/reducer without approach lines (abrupt change on diameter) etc. Wondering if anyone can point me at here I can find the formula to calculate those. I don't mind seting up my own spreadsheet or matchcad or matlab, whatever :D, but available spreadsheet is certainly welcome.
Also a basic question, is there a max limit for flow rate in a pipe given a internal diameter? What is limiting factor if any? How to calculate it?
Thanks a lot in advance.
salmon2
Just got a task to do some calculation about our hydraulic control system. I have enough education to understand the dynamics, etc but almost never worked on such real problems.
Spent tody online and already got some ideas about how to calculate pressure drop in pipes. But need to know more cause our system got a lot of components such 90 or 45 deg elblows, branch and running tees, enlarger/reducer without approach lines (abrupt change on diameter) etc. Wondering if anyone can point me at here I can find the formula to calculate those. I don't mind seting up my own spreadsheet or matchcad or matlab, whatever :D, but available spreadsheet is certainly welcome.
Also a basic question, is there a max limit for flow rate in a pipe given a internal diameter? What is limiting factor if any? How to calculate it?
Thanks a lot in advance.
salmon2





RE: Basic formula to calculate pressure drop
http://en.
For minor losses due to fittings you can read
http://www.cheresources.com/eqlength.shtml
You can also look for Hooper 2k method and Darby 3k method (there are around several threads on this topic)
RE: Basic formula to calculate pressure drop
There was a recent thread (I believe it was in this forum on eng-tip.com, but I'm not certain) on this subject that discusses limitations of the various techniques, but it would be a lot easier to follow if you had a Crane #410 in your hands while going through it.
David
RE: Basic formula to calculate pressure drop
http:
Good luck,
Latexman
RE: Basic formula to calculate pressure drop
Thanks
katmar
RE: Basic formula to calculate pressure drop
http://www.pr.com/press-release/199848
Access to calculator at the link below
http://www.flowoffluids.com/calculators.aspx
Note: As unit converter I definitely prefer Uconeer (found a bug in °C to °R conversion in flowfluid tool)
RE: Basic formula to calculate pressure drop
I had it shipped to a new engineer at one of our plants. I didn't even see it.
Good luck,
Latexman
RE: Basic formula to calculate pressure drop
David
RE: Basic formula to calculate pressure drop
RE: Basic formula to calculate pressure drop
But seems like no formula available to calculate either f or K for valves or fittings, which is what I really need.
RE: Basic formula to calculate pressure drop
Just recently in thread407-292861: Minor Loss Coefficients a very similar question was asked, and several links and tables were included there. If you Google for the specific pressure loss in which you are interested - e.g. "pressure loss in elbows" I'm sure you will find more than you will ever be able to read.
There is also a completely free, but fairly simple calculator available from http://www.elefantin.nl/dP/index.htm There are others online as well if you don't like SI units.
Katmar Software
Engineering & Risk Analysis Software
http://katmarsoftware.com
RE: Basic formula to calculate pressure drop
Informative. I didnot know crane 410 at all before. I usually don't buy
Books any more given Internet resoures. Also when you got the
Book you will never read it again.
RE: Basic formula to calculate pressure drop
David
RE: Basic formula to calculate pressure drop
Please take a look here for a some basic understandings and values (credted to IUPUI university):
local losses
Two good links to start looking for some k values on Internet:
Local Coeff 01
Local Coeff 02
I'm sure you'll find more by googling.
And here's a free Excel sheet:
Friction Excel
Finally, I recommend to download Epanet (it's free) and model your system easily with this software. you can have user-defined elements to assign your desired K values to them.
About your last question: Do you have a gravity line or pumped one? With gravity, the available static head dictates your pipe diameter. you can not make the pipe smaller cause there will be more head loss and less flow. so you should tale a diameter that passes your desired flow. on the other hand you don't want unnecessary large pipe to pay extra money for larger pipe.
if it's a pumped pipeline then there's no limitation! unless you want to restrain your flow velocity due to:
- high friction loss (more speed-->more friction loss-->bigger pump, higher pipe pressure class, more energy cost)
- your pipe lining can not tolerate the erosion
In water sector, normal water velocity range is between 0.5 to 3 m/s. economic diameter could be around 1.5 to 2 meter depending on where in the world you are located.
Hope this would help.
RE: Basic formula to calculate pressure drop
RE: Basic formula to calculate pressure drop
Here's what is supposed to be updated (the forward goes into a bit more detail, but basically says the same thing)...
New in the 2009 Edition:
For the 2009 edition, additional valves and their resistance coefficients were added based on tests performed within the Crane Engineering Laboratories. Industry research was gathered on the latest calculation methods for hydraulic resistance and in resistance values for wyes and tees. Chapters on pumps, control valves, and flow meters were included and over thirty-five new sources have been added to the book.
RE: Basic formula to calculate pressure drop
Here's the correct link to the Exceel spreadsheet mentioned by waterpipe
ht
RE: Basic formula to calculate pressure drop
Katmar Software
Engineering & Risk Analysis Software
http://katmarsoftware.com
RE: Basic formula to calculate pressure drop
@CarlB: Thanks for the cover! I don't know what went wrong with the link.
RE: Basic formula to calculate pressure drop
RE: Basic formula to calculate pressure drop
Let your acquaintances be many, but your advisors one in a thousand' ... Book of Ecclesiasticus
RE: Basic formula to calculate pressure drop
Mott MacDonald was my one time employer
Regards
athomas236