Down pipes are typically about 10 cm diameter. That way, they fit the rain gutter bottom width, and can handle heavy rainfall if the gutters are clear of leaves.
Your rainfall should be in meters per year, not kiloliters per year, unless you have already taken the roof area into account.
Hey
What size down pipe would I need, and how many if my roof area equals 1224.78 metres squared and I have average rainfall of 173kl per year?
Also how much plumbing would I need from my hypothetical tanks?
4 answers
The size downpipe does NOT depend on average rainfall per year, but the rate of rainfall (inches/hour). That is a statisctical exercise, because you probably wouldn't want to design for the max rainfall rate, but rather something like design to catch the flow of something like 90 percent of maximum rainfall. There is a cost tradeoff here.
If you lived in the desert, you might want to design for max rainfall.
If you lived in the desert, you might want to design for max rainfall.
Thanks. Talked to my Dad. Told me to assume that the down pipes had a width of 200mm as this is for a school auditoriam.
@ drwls. Yes, the roof area has already been taken into account
@ bobpursley. how would i design for max rainfall? The school is in the desert.
@ drwls. Yes, the roof area has already been taken into account
@ bobpursley. how would i design for max rainfall? The school is in the desert.
Max rainfall? That is what weather records are for. Look them up.
Then, you have the flow /min, and the length of pipe, and the pressure head (due to gravity). Bernoulli's equation rules, or you can use any number of online pipe flow calculators to figure this.
Then, you have the flow /min, and the length of pipe, and the pressure head (due to gravity). Bernoulli's equation rules, or you can use any number of online pipe flow calculators to figure this.
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