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Sizing storm leader,, 18,200L

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kami4444
kami4444 Member Posts: 33
With two roof drains in a storm system that runs to the storm building drain. The roof / storm drain takes 18,200L. What size should the leader / horizontal storm drain be?

a) 4"
b)5"
c)6
d)7

I would appreciate it, I want to understand it.

Comments

  • hot_rod
    hot_rod Member Posts: 22,251
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    Sounds like you are looking at some sort of plumbers test? They should supply you with study guides or recommended textbooks needed to research and study.

    There is a difference between knowing an answer and understanding as you mentioned.

    ecodes.biz is one of many places to find code books, one example below.


    http://www.ecodes.biz/ecodes_support/free_resources/Louisiana/Locked_PDFs/Appendix A_Roof Drain Sizing Method.pdf
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    Gordy
  • Zman
    Zman Member Posts: 7,572
    edited April 2017
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    In the US, you can find the code requirements in the UPC. You will need the pitch of the pipe. This should be included in the question. The actual flow rate would also be needed. Is liter per day? Year? Minute? Hour?
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
    Gordy
  • Gordy
    Gordy Member Posts: 9,546
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    Yeah, that's 4808 gallons. I would assume that is sized for a maximum event.

    Just to put things in perspective 1" of rain will produce 2800 gallons of water off of a 4500 SF roof. However if the 1" of rain happens in an hour, or if it happens in 24 hours is a whole different situation, and requires a different piping management to get that water away efficiently.


    So what I'm saying is any of those answers could work, or be right. However it depends on codes, pipe pitch as @zman said.

    From what I have seen posted the questions are a bit broad on description. Unless you are not relaying the exact wording of the question.

  • Gordy
    Gordy Member Posts: 9,546
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    Maybe if YOU could give us a little more information as to the type of testing, and country of origin since metrics is involved. We could help a bit more.

    strikes me as odd that water volume is in liters, and piping size is in inches.....
  • Gordy
    Gordy Member Posts: 9,546
    edited April 2017
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    As you can see in the table I have attached there are some code specific details that must be known to size the horizontal leader.

    Also note that the table is based on area of drainage. Which is based on a 4" per hour rainfall event.
  • Gordy
    Gordy Member Posts: 9,546
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    Also note the pipe pitch. By going from 1% to 4% slope you can double the area of drainage for the same amount of rainfall with in the same pipe size....
  • Jamie Hall
    Jamie Hall Member Posts: 23,426
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    The question as posed cannot be answered. Provide more information.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    Gordy