Tail Pipe on Fixture or Drain
Tail Pipe on Fixture or Drain
(OP)
The Uniform Plumbing Code details that a tail pipe, i.e. vertical run of pipe underneath a fixture before the the trap occurs, may only be a maximum of 24" long or must be a 45 degree angle with a maximum 24" vertical distance. I understand the purpose of the maximum length such that a plugged trap would only hold a static head of only so much. On my project I have several situations where structural beams are over 24" deep, some cases more than 36", that support the floor above. I have two questions:
1) Does this plumbing standard only apply to fixtures and not floor drains?
2) Does anyone have a suggestion as to how one would pipe this. The beam depth depicts the total vertical distance that must be accommodated before the horizontal wasteline can begin. The material of the pipe is cast iron.
Thanks.
Togel
1) Does this plumbing standard only apply to fixtures and not floor drains?
2) Does anyone have a suggestion as to how one would pipe this. The beam depth depicts the total vertical distance that must be accommodated before the horizontal wasteline can begin. The material of the pipe is cast iron.
Thanks.
Togel





RE: Tail Pipe on Fixture or Drain
Thanks.
RE: Tail Pipe on Fixture or Drain
John Peterson
www.wba-arch.com
RE: Tail Pipe on Fixture or Drain
RE: Tail Pipe on Fixture or Drain
In general, if possible, run parallel to the structure until you can get to a wall or something else to vent the pipe. Then you can drop vertically and go below the structure.
If this is not practical, contact the code official and let them know your situation. I had a situation where there complying with the 24" rule would have cost $$$$ in modifications to the fire protection to the building structure. Therefore, we could exceed the 24".
RE: Tail Pipe on Fixture or Drain
I think (and I may be wrong) that the reason it limits it to 24" is becasuse if it gets longer, the water from the fixture will have extra momentum on the vertical drop which transfers directly to the trap-seal water. This of course can cause the water in the trap to be "pushed out" or drain (partially) thereby eliminating or reducing the water seal (although some water will probably still remain in the trap).
At any rate, the code officials may allow a variance, but the particular fixture may be more inclined to siphon.
RE: Tail Pipe on Fixture or Drain
But the 24" maximum is to reduce odor and the growth of bacteria upstream of the trap. Buildup on the wall of the fixture outlet pipe will breed bacteria and cause odors to develop.
This is an excerpt from the IPC Code Commentary.
This 24" rule is often violated with washer machine standpipes which typically have a long vertical section prior to being trapped. It was not until recently (at least in the IPC) that washer standpipes had to be vented. This was probably due to the self siphoning you mentioned.