[QUOTE 4924400, member: 9609"]that is a nice little calculator and gives even better increase in flow rates that my earlier guess, I had guessed 2.89x based on cross sectional diameter of pipe
but that shows increasing pipe from 12 to 20 mm would give nearly 4x - which would be what I am look for.
How do you think it works if a pipe with two differant diameters are used. out of the 3m if 1m was 20mm and 2m was 25mm, would ou use the average of 23.3mm ? (that would give me nearly 6x the flow)[/QUOTE]
I'm no expert, but I suspect it very much depends on where the different pipe diameters are used, and what the head is at each section. There are online calculators that deal with such complexities, but they may not be freeware.
Here's some stuff on equivalent straight pipe lengths, page 78.....
file:///C:/Users/Martin/AppData/Local/Microsoft/Windows/INetCache/IE/X8D4VNMR/copper_tube_handbook.pdf
I'm sorry it's in imperial units. Scratch about and you'll find stuff in metric ones.
I'm always disappointed by estimates of fluid flow, whether liquid or gaseous. Just oversize everything!
Edit: Sorry, bad link. I'll try and find another.