Vent pipe under sink??

[Kelm130]

Hi - I was replacing my bathroom faucet and saw this under the sink. Looks like the vent for the gray tank. Can that be?? Do others have this setup?




Thanks
Ben

[Kelm130]

Ok after about 5 minutes of google research I see that it's fairly common setup. Its supposed to have a flap of some sort to let air down into it but not up out from it.



Just seemed a little squirrely when I saw it. I'm having a difficult time stepping down form a Winnebago Journey to a small camper lol. There is a world of difference in how they are put together. Sigh "Serenity Now"

[Old-Biscuit]

That is an AAV....Air Admittance Valve.
Installed downstream of sink drain 'P' traps.
They OPEN due to negative pressure being created in drain line when dumping grey tank....allows air in breaking the negative pressure and preventing 'P' trap from getting sucked dry.
You have a better quality AAV then is normally used in RVs (Oatey Sure-Vent)