DWV system query - vertical for 6" above flood level required?

[ZanneJ]

I'm asking here because on another forum, a person in Airzona had a plumber install the plumbing for her sink and he had a 90 elbow and a horizontal run below the flood level of the sink. We told her about the rule requiring a vertical run for at least 6" above the flood level of the highest fixture. When she asked her plumber about it, he claimed that the Arizona Plumbing Code had an exception to that rule and that it was not required if it was just a single sink tied in to the vent.

Is that true or is the plumber BSing her?

 

[jar546]

More specifics please. Are you talking about an AAV or vent connection, flat vent, etc?

 

[steveray]

Island vent?

 

[ZanneJ]

She was talking about the vent for a sink inside the wall. She posted this image:

The flood level of the sink will be above the first horizontal run of the vent pipe. Her plumber told her that it was ok to run the pipe like that, but some other plumbers said they did not think it was right.