Yet another "island" vent question

[JG@TL]

Is it permissible (in Chicago) for the drain line of a first floor kitchen island drain to run vertically to a drain in the basement floor below the kitchen, rather than "horizontally" (with 1/4" slope) to a vertical plumbing stack?

Thanks in advance for your help.

 

[Reach4]

Out of the trap, the trap arm must stay horizontal for at least 2 pipe diameters before the vent. The line must stay horizontal until at least the vent. At that point the line may turn down.

When the vertical line then turns horizontal, that is a common place for a blockage to occur. That turn at the bottom should be a long sweep. That may be under the basement floor already. So at least put a cleanout in to make cleaning that turn easier.

I am not a plumber.

 

[Sponsor]

 

[JG@TL]

Out of the trap, the trap arm must stay horizontal for at least 2 pipe diameters before the vent. The line must stay horizontal until at least the vent. At that point the line may turn down.

When the vertical line then turns horizontal, that is a common place for a blockage to occur. That turn at the bottom should be a long sweep. That may be under the basement floor already. So at least put a cleanout in to make cleaning that turn easier.

I am not a plumber.

 

[JG@TL]

Thanks for your reply, and that is good advice about potential blockages when the drain turns from vertical to horizontal, especially below the concrete basement floor.

But all the diagrams of island venting I have seen show traps emptying into vertical drain lines above the kitchen floor then turning "horizontal" (with slope) below just below the floor, with the looped vent line running sloped slightly upward above the drain line. Some diagrams show a drain connection downward from the vent line to the drain to handle blockages.

What I am asking is whether the island drain line can run straight down to to a drain in the basement floor, rather than turning "horizontal" a foot or so below the floor. This would mean that the drain line would run vertically about 10 feet before it goes horizontal below the floor.

 

[Reach4]

But all the diagrams of island venting I have seen show traps emptying into vertical drain lines above the kitchen floor then turning "horizontal" (with slope) below just below the floor

from https://terrylove.com/forums/index.php?threads/kitchen-sink-vent-issue.27999/ #12

 

[JG@TL]

from https://terrylove.com/forums/index.php?threads/kitchen-sink-vent-issue.27999/ #12

Yes, That diagram expresses my question exactly. Thanks for posting it. (I guess one picture is worth 1K words).
My issue is: my "ground" is 8 feet below my kitchen floor: Would that kind of drop be permissible? Would the accelerating water create suction that might empty the trap and/or cause other problems?

 

[Reach4]

My issue is: my "ground" is 8 feet below my kitchen floor: Would that kind of drop be permissible? Would the accelerating water create suction that might empty the trap and/or cause other problems?

Yes. Support PVC every 4 ft. I based that on http://www.engineeringtoolbox.com/drainage-pipe-supports-d_1106.html

I would presume that the venting requirements take that into account. It seems to me that there are actuall two paths for venting in practice, regardless of any official designations.

 

[hj]

IF you do the rest of it properly, it does not make any difference how long the drop is below the "vent tee".