Any sprinkler contractors? Fluid dynamics engineers? Help determine water pressure
If you have a six inch line at pressure A, and then reduce that line down to two inches, the pressure will still be A. The difference will be how much flow (gpm) comes out of the two inch line versus the six inch line. If you can get 20 gpm at the end of the line at your value of 45 psi, then one 13 gpm head will work fine and the pressure will still be 45 psi. If you put two 13 gpm heads on that line, then you will need to increase you delivery capacity to 26 gpm- either by increasing line pressure or supply line diameter. What will happen is that at the same 45 psi, with two heads requesting 26 gpm total you will only get about 10 gpm to each head, assuming that they are equidistant from the pump. In reality, most likely the closest one will get a little more pressure, and subsequently a slightly higher output.
Or, you could just put a pressure gauge on the line.
If it's worth doing, it's worth doing right. If you wouldn't put your name on it, it ain't done right!
Last edited by downunder; 07-31-2009 at 07:25 PM.