What is this fixture and why is it leaking?

[Danspot]

I'm trying to fix a leaky shower head in the kids' bathroom - figured I'd just remove it, add some pipe tape, and tighten back up.

But doing that didn't fix the leak, which was farther up, coming from some kind of a gasket that connected the wall to the flexible hose. It has a metal part with a hole in the center and a ring of holes around the outside, and two each rubber and plastic gaskets. I think it has something to do with letting air back into the pipe, or preventing backflow... maybe it's called a vacuum breaker or a backflow preventer?

I first tried to tighten it up all the way, which just stopped the water completely. I then loosened it to the point that water came out the center hole (for the hose and showerhead), but there was still leaking from at least one of the "outside" holes. I also experimented with different orders of applying the gaskets. Right now they are 1-2-3-4 per the picture, in that orientation.

I'm _guessing_ that I probably have the gasket order right and one of the rubber gaskets is failing (not obviously, but maybe it's not compressing enough), so I just need to replace the doohickey. But to do that, I need to know its name...

Any help on the name and our potential root cause would be very much appreciated.

 

[Jadnashua]

I think that it's a vacuum relief safety device. If the hand-held showerhead were to be submerged, it will prevent that dirty bathwater from being sucked into the supply line in rare conditions, potentially polluting your drinking water. Often, it's easier to replace, but you might be able to buy a repair kit. There's a similar type device on most new hose bibs you use for watering the garden, or washing the car outside.

 

[Sponsor]

 

[Danspot]

Perfect, thanks @jadnashua Using that info I found it online: Hansgrohe 06510000 vacuum breaker. http://www.hansgrohefixtures.com/hansgrohe-06510000-external-vacuum-breaker-chrome.html

Seems like these fail every few years due to the rubber gasket, so I might try another company's just to test.