Water pipe sizing flush valves

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by yngwie_69, Apr 4, 2014.

  1. yngwie_69

    yngwie_69 New Member

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    Sep 8, 2009
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    Prince Rupert, BC
    Is there a code for a certian amount of flush valve toilets where you have to increase the size?
     
  2. Sluggo

    Sluggo Member

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    Mar 28, 2014
    Location:
    WA
    What is the situation? A residence? A dormitory? A prison? I don't know about Canadian requirements, but since a modern toilet will only use about 6 liters, and the tanks refill quickly, and the likelihood of a lot of people flushing a lot of toilets all at the same time is low, I would find it hard to believe that this would be a practical or code issue. Just my 2 cents...
     
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  4. hj

    hj Moderator & Master Plumber Staff Member

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    Quote; Is there a code for a certian amount of flush valve toilets where you have to increase the size?

    Assuming that by "flush valves" you mean "flushometers", then of course there is, and even if there were not you would have to do it to maintain volume when they were operated in unison.
     
  5. yngwie_69

    yngwie_69 New Member

    Joined:
    Sep 8, 2009
    Location:
    Prince Rupert, BC
    FLush Valves


    There may be a possibility of 8, first one requires 1". If i recall you had to up size to at least 2 1/2 to had worst case scenerio.
     
  6. hj

    hj Moderator & Master Plumber Staff Member

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    Location:
    Cave Creek, Arizona
    The actual pipe sizes, depend on the locations of the valves relative to each other and the length of the supply piping. Normally, you could feed 8 of them with a 1 1/2" line, but job conditions could alter that.
     
  7. yesky

    yesky New Member

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    Jul 19, 2015
    Location:
    Toronto, ON
    I have the same question: since almost all the states in the US and Canada have same requirement in the codes: the first flush valve water closet has 40 Fixture unit, second has 30 FU, third has 20FU, the fourth has 10 FU. The plumbing code now is changing from 10 FU in the past for public use to 40 + 30 +20 +10.... should we increase the water supply main size? The 1-1/2" pipe now can support 8 WCs under the new plumbing code?
     
  8. Terry

    Terry Administrator Staff Member

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    Aug 17, 2004
    Occupation:
    Plumber
    Location:
    Bothell, Washington
    You work backwards on the pipe sizing charts. If after adding up the fixture counts you have to increase size to the meter, then yes.
    With Flushometer toilet and urinals, you need a big enough supply to handle it.
    Tank type toilets can typically get by with smaller main supply sizing than Flushometer types.
     
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