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How to vent a floor sink when the nearest wall is ~10' away?

Discussion in 'Commercial Plumbing Codes' started by Michael.L, Jun 7, 2018.

  1. Michael.L

    Michael.L Sawhorse

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    I'm laying out the floor plan for a small cafe. There will be a coffee bar at the service counter with a 3-compartment sink. The 3-comp sink's drain will be indirectly plumbed to a floor sink below with a required air gap. But the closest wall is 9.6 feet from the location of this floor sink. Is it acceptable for the vent to be that far from the floor sink trap? Do I just upsize the fixture arm drain pipe to ensure that the vent connection opening remains above the trap weir?
     
  2. Keystone

    Keystone Sawhorse

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    Why not use an Auto Air Vent?
     
  3. Sifu

    Sifu Gold Member

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    Combination waste and vent.
     
  4. mtlogcabin

    mtlogcabin Sawhorse

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    If the 3 compartment sink is also being used as a food prep sink then it should be going to a grease interceptor

    3 " drain will allow 12 feet from the trap to the vent
     
    Michael.L and Pcinspector1 like this.
  5. Michael.L

    Michael.L Sawhorse

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    It's not a food prep sink, but it will be used to wash out milk steaming jugs and blender jars. It will be drained to our grease interceptor.

    Are you sure? According to this graphic, a 3" drain will only allow a max trap arm length of 6 feet, and that I'd need a 4" or larger to get the max trap arm length to 10 feet.

    [​IMG]
     
    #5 Michael.L, Jun 7, 2018
    Last edited: Jun 7, 2018
  6. Michael.L

    Michael.L Sawhorse

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    One reason is that they tend to make a noise like a "whoopie cushion." Not exactly what you want customers to hear at your cafe's service bar.
     
  7. Michael.L

    Michael.L Sawhorse

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    Like this?
    [​IMG]

    I don't know if the existing sewer line under the slab is deep enough to allow this type of configuration.
     
  8. Keystone

    Keystone Sawhorse

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    I can understand that.

    mtlogcabin is spot on, if your using local jurisdiction uses IPC then you will be okay. Chapter 9, Venting from the IPC allows up to 12ft when using 3" drain at 1/8" slope.
     
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  9. Pcinspector1

    Pcinspector1 Platinum Member

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    2012 IPC TABLE 909.1
     
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  10. Michael.L

    Michael.L Sawhorse

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    Thank you for the code reference. That's always better than random images culled from the interwebs. :p

    My apologies to Mtlogcabin for doubting you!
     
  11. ADAguy

    ADAguy Sawhorse

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    What you show is an island vent, commonly used on residential kitchens.
     
  12. Michael.L

    Michael.L Sawhorse

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    Our service bar will essentially be an island. I'm curious: why plumbers would install an island vent like that rather than just upsizing the trap arm pipe to 3" (or 4")?
     
  13. mtlogcabin

    mtlogcabin Sawhorse

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    My apologies for not including the code reference table
     
  14. HForester

    HForester Member

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    AAV = Air Admittance Valve
     

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