Question
Hi Matt,

I am mapping out an irrigation plan for my backyard.  I have a slope at the
back end of my property that is maybe 20' high.  When I run the numbers, it
seems like I dont have enough pressure to irrigate the slope.

I measure 54 psi static pressure at the point where i will tap in for my
irrigation.  Taking into account friction loss from Double Check Backflow
Preventer (8 psi), water meter, angle valves, 175' of pipe to farthest sprinkler
head, and loss from elevation (20' x .43 = 9), and rotary head (min psi
25).....it appears that the combined pressure loss from above exceeds my
starting pressure of 54 psi.

Are my calculations correct or am i missing something?  And if I am correct,
what can I do to irrigate my slope?

Thanks,

Ed

Answer
Ed,
You have calculated you pressure correctly. The 2 you can't change are the elevation and the backflow prevention, those are fixed losses.
Try lowering your water usage rate. At 10 GPM you auto valve will be 3PSI loss. Using 1" pipe the loss will be a couple # per 100'. So you would still have 25PSI at the sprinkler. It may cost you an additional valve but it is cheaper than the alternatives.

Matt