What is it?

[Tom Rees]

Found this at inspection today and I have never seen this before. At the top of pipe off of disposal this was screwed on, you can see the threads at top of white pipe. It has a clear plastic diaphragm on top. Also the kitchen sink was on an island and where I would expect to see a mechanical vent there is a rubber cap. What is going on?

[Chuck Moeschberger]

Found this at inspection today and I have never seen this before. At the top of pipe off of disposal this was screwed on, you can see the threads at top of white pipe. It has a clear plastic diaphragm on top. Also the kitchen sink was on an island and where I would expect to see a mechanical vent there is a rubber cap. What is going on?

Looks like a handyman mess to me. I was a pipe fitter for 3 years and we found things like this sometimes. It doesn't serve a purpose if you ask me.

[Jerry Peck]

You've got two problems shown there, one where the incorrect drain piping is connected to the disposer and the other where there should be an AAV, which looks like someone removed it and capped off the top of the VENT, which means that sucker ain't gonna vent like it should.

[Tom Rees]

Jerry, Have you seen this diaphragm thing before?

[Jerry Peck]

Jerry, Have you seen this diaphragm thing before?

Tom,

Yes ... sort of ... ;)

In your second photo, see that white slip fitting nut with the two wings on it to allow tightening it (some slip fitting nuts do not have the wings on them), now take a scrape piece of copper or steel, maybe even the cut out top of a soup can, use a hammer and pound it down into that slip nut, and ... ;)

You'll have a matching white nut with diaphragm. :)

That piece is a tailpiece/tailpiece extension with a side inlet for another line, in this the disposer is connected into it. Notice, though, that the connection is a slip joint fitting - the discharge pressure from the disposer 'could' push the slip fitting and nut off the end of the disposer discharge ... makes a big mess when that happens.