DWPC,

Distance of water throw per head is dependent upon pressure. heads usually have several distances called out for various pressure levels. The max distance is usually for the maximum pressure which is usually around 60 psi. What is your system's operating pressure? Once that is known then check the irrigation literature. All the top irrigation companies have sites to give you these details. If they don't have a write up on this you will probably be unhappy with the results of trial and error. JMHO Aloha

lehua13:
My supply pressure is 90 psi and I plan to install a pressure reducing valve to regulate it to 50. I can get Hunter MP1000 nozzles on pressure-regulating heads to get the 8' to 14' ft radius I need. I'd prefer to use Toro Precision series rotary nozzles but I'd have to cut it to 25 psi to get 14 ft with the Toro. I also have wondered if the flow control on the valve will reduce pressure significantly.

dwpc,

I will do some research on your irrigation heads some time soon. Pressure and orifice size corresponds directly to the distance of the water throw of the head. So unless the flow is reduced with the Toro it is unlikely to have a similar throw distance with a significantly lower pressure. 25 psi is a good low pressure for drip systems. Do not use a control valve to reduce pressure. You will get uneven flow and uneven pressure downstream. Does anyone think differently because this is JMHO. Aloha

dpwc,

The information I have perused states that radius of irrigation below 18 ft should be by spray head not rotor spray head. Aloha