you should look at your pump chart to determine what your pump will put out.
You can compute the flow rate through an orfice but such that drill bits do
not make round holes your figures will be off. I cannot answer your
question but gave you some info for next time around.
Al

"Karl Townsend" wrote in message
anews.com...
Most unusual frost/freeze predicted tomorrow. We're looking at winds 18
gusting to 25 with freezing conditions. The strawberries are in bloom.

Standard protocol for still condition frost in strawberry is one sprinkler
every 60 feet by 60 feet with a 9/64 nozzle. At 70 psi you get about .1
inch per hour and protection down to 27 or 28. This don't get it for wind,
you need a lot more water. There's a convective cooling effect. I need to
be in the .3 inch per hour range.

I can double flow by protecting 1/2 the area and running a sprinkler every
30' by 60' spacing. Not quite there. My particular pump will run 40 9/64th
sprinklers at 70 psi. I don't know flow rate but its around 125 gallon per
minute.

Now for my question, I'm going to run 25 sprinklers on this pump and I
need to bore the ID out to match the pumps flow and get 70 psi. What
diameter should I try? I can't go smaller once bored, but I have time for
two trials. I'm guessing three hours work to remove 25 sprinkler nozzles,
bore, replace, and then test pressure.

Karl