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Wednesday, April 7th 2004, 5:42pm

Flow Rate

I am in the process of double checking my design before making the order. I would like to confirm the following:

My house does not have a water meter. The line from the city is 1" poly (the black pipe). The sprinkler line is also 1" poly and tees off from the main line once this line enters the basement. Using a pressure gauge on the water hose bib, I measured a static pressure of 60 psi. According to all of the design tables that I have found, the maximum flow for my 1" poly sprinkler line should be 23 gpm. The design books that I've read have suggested designing the system to 80% of the maximum flow so as to allow for future expansion and water use in the house. 80% of 23 gpm is 18 gpm, which I have used for my design.

Does anyone see a problem with my design flow rate? For what it is worth, I will be using 1 1/4" CL200 poly pipe for the laterals and 1 1 1/4" Sch40 PVC from the main line to the control valves.


rain man

Active Member


Thursday, April 8th 2004, 4:03pm

Your flow rate is fine. At 18gpm you will have a water velocity of 6.7 ft/s, you want to keep this under 7.5 ft/s to avoid damage to system. How do you not have a water meter from the city?

rain man

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