On Wed, 21 Oct 2009 08:43:33 -0400, Jim Elbrecht
wrote:

That solves the problem of not being able to have a vent pipe on the
drain where it is located and works with a P trap. It does not
eliminate the need for a P trap, which is what the stated problem is.

I am not a plumber-- and I know some codes don't allow them. But
they work fine as a vent, and don't allow sewer gas into the house.
[the latter being the purpose of the p-trap, right?]

Yes, but you are talking about two separate things. The p-trap keeps
gas from entering the house via the drain in question. The device you
are talking about lets you create a vent inside the living space
without letting sewer gas enter via the vent. The OP has the first
problem, not the second. He wants to keep gas from entering via a
trapless drain.