OLD CIPE EXAMPLE
Hello. I'm studying out of the old cipe exam review manual and I have a question about on of the examples, in the domestic water system section. The example illustrates the procedure for sizing a system with a booster pump.
The static pressure for highest outlet = 180ft. x .443 = 77.94psi
street pressure is 45psi
total length of run the farthest highest outlet = 350ft.
friction head loss is 5/100ft. elr = 350ft. x 1.5 = 525ft (5/100)x525 = 26.25psi
required outlet pressure = 20psi flush valve water closet
head loss through PRV at pump = 5ft. 5ft x .433 = 2.165
Total required initial pressure = 129.19
total fu load 4840fu = 582gpm
I don't understand where the 129.19psi required initial pressure comes from.
I believe the total initial pressure should be the 77.94psi + 26.25psi friction head loss which = 104.19psi I have a difference of 16 psi.
Question is where am I missing this 16psi or is the book wrong?
I see a few issues,
180 x .433 should be 77.94
350 x 1.5 x 5/100 should be 26.25
PRV loss - 5 x .433 = 2.165
Total all above = 106.355
Now add the min pressure at highest fixture = 20 + 106.355= 126.355psi
The writer of the book may have mean't 5 psi drop on the PRV and if so
it would add 2.835 psi to 126.355 resutling in 129.19 psi..