I do not remember seeing one but I will go look specifically for that water trap.
In my old house I had a galvanized flat attic vent the straddled a strut.
That made so easy to drill and attach directly to the strut.
I wanted to try this fume vent to avoid any drilling.
I have seen people attach clamps directly to the exterior of the vents but my vents are so short...
I will definitely not plug the TV antenna piping, I want those fumes to keep on going up
VReihen in Arizona the standard is to use PVC from roof down to the drain pipe.
Then a galvanized fitting that shrouds the PVC is installed to make a negative seal with the roof.
Finally they curl the galvanized fitting into the PVC so no rain water can slip between the fitting and PVC.
My current house has six of these fume vents, and a rather tall furnace fume stack none of which are grounded...
My other option is to clamp to the furnace fume pipe (galvanized)
I am still debating on that one instead of the drain vent...
Randall