bigger pipe = greater pressure = higher flow rate!

[Vortechs]

My hydro used to have a 250 meter run of pipe which was half 3" and half 2". My summer nozzle was 9mm and used 1.5 liters per second, which was perfect for getting me through the summer drought, but last winter I upgraded the pipe to all 3" and it wasn't until I ran out of water yesterday that I realized: bigger pipe = greater pressure = higher flow rate!   
Is there a way to calculate the nozzle size I need now from these figures to get back to the 1.5 Ltr/sec, or am I just going to have to try and do it the hard way with a bucket and stopwatch and get soaked until I find the right size? (Standing pressure is 48psi, running 44psi)
Thanks 

[gizmo]

The larger pipe wont affect your standing pressure, but can affect your running pressure, especially for a long feed pipe. Was the 44 PSI the running pressure before the pipe upgrade? If so, you could add a restrictor to the inlet to get back to the same running pressure, and then expect the same water usage.

Glenn

[Flux]

If there was no pipe loss the consumption would be proportional to nozzle area.

If the pipe was restricting effective head then the big pipe would increase spouting velocity and hence flow.

Assuming the pipe is not now restricting head much, if you measure the flow now, you know the nozzle area so you can calculate the new area for the flow you want. Calculate diameter from the new area,

This will be approximate as there lots of assumptions about the pipe loss but it may get you in the right region.

You will make better use of your new pipe by reducing jet size rather than restricting to get back to the old pipe loss but if it worked before then it should work again

Flux

[hydrosun]

Just put in the next smaller sized nozzle and check your amp meter. If it is close to the output you got before the pipe upgrade you are done. With the larger pipe you should get a bit more power with the same amount of water. You will have to decide if you want to fine tune it to get the maximum power at exactly 1.5 lt/sec.
How are you changing the nozzle size? Is it the type where you cut off the tip until you get the right opening?
Chris