Started re-doing my bathroom and found this odd layout in the

Damn phone rotated the pic. It should be turned 90* clockwise.

Water hammer arrester. They should be full of air so that when a hammer of water comes in it can compress the air like a spring and normalize pressure gradually instead of making the pipes knock like crazy.

Something about your house probably needs them if it has them.

>>904580
Good to know! I couldn't figure it out from Google, but I know what you mean by rattling pipes!
House built 1890 so I bet it does need them petty bad

>>904609
If knocking pipes are still a problem you could call a plumber.

Your house might not have a pressure regulator if it's that old. The city could be supplying more pressure now than when it was built. If it's 1890 those arresters might be busted too. You could try recharging them. Internet says:

"The old style, low tech solution is simply a vertical length of line that naturally fills with air (as opposed to charging it) to absorb the vibration. Over time, the air is absorbed into the water and you get the hammer. To "recharge" the simple absorber, turn off the supply, open the lowest tap (usually a garden hose) and another tap inside the house to drain the system and allow air back into the vertical pipe. Turn the supply back on, purge the air from the lines and you're back in business for the next few years. QED."
http://forum.woodenboat.com/showthread.php?143262-Water-hammer-arrestor-replacement

>>904580
So basically capacitors?

>>904831
no, more like shocks....

File: oscda8[1].gif (30KB, 579x414px) Image search: [Google]

30KB, 579x414px

>>904834
>>904831
all of these things and others function on the same mathematical principles.

Science, bitches.

>>904831
https://en.wikipedia.org/wiki/Hydraulic_analogy
Wikipedia says that's not quite the right analogy.
These are more like inductors, indeed they are used in hydraulic ram pumps as the article states.

>>904836
Yeah sine waves are just simple harmonic motion so I'd imagine something compressible would just filter them accordingly.

>>904839
An inductor allows current to flow through it though. This water arrestor is a dead end, surely more like their diaphragm analogy?

>>904578
do you live in mass
i live in maine, and mass is the only place i have ever seen where air chambers are code

>>904869

That guy's off his ass. They're definitely more analogous to capacitors in that they damp or resist changes in pressure rather than changes in flow.

Keep in mind, that a water line has a finite capacity. When it is sitting there, moving no flow, it still has a static pressure. When you turn on a facet or shower, water starts flowing, and you can lose some of that static pressure until the entire line catches up with the flow. Then, when you turn the faucet off, there is a minor pressure wave that has to bounce back down the line, because the water keeps wanting to flow, but has no immediate place to go. Part of the reason for those units is to allow the pressure wave to compress the trapped air (momentarily) until the pressure in various parts of the pipe equalizes, and goes back to a static pressure with no flow. The first time I encountered those, they were galvanized stubs, in an older Florida house.

>>905010
so are they just hollow on the inside with nothing to keep the water out other than the air trapped in them? wonder how often people install them upside down and don't realize the air will bubble out?

>>905024
All the ones I have ever seen pointed up. So, unless there was a leak near the top, the air would stay there. I vaguely recall something about bleeding the line, would restore the level to original, because you remove all the water.

Now, to add one more thought ... The very first time I ran into these was in a house I lived in, and we began hearing a hissing sound in the wall, followed by a little water seeping under the cabinet. After considerable tearing apart of the cabinets and wall, it turned out that the 30 year old copper bounce pipes, had corroded exactly at the level where the water would have met the air pocket. Some older copper pipes had a real bad habit of corroding little pin holes. Major PITA of a repair.

>>905024
Some of them do have bladders in them, but ops look fairly old, and they would have dissolved anyway.

PLumber here, they are actually dildos

They are mostly found next to something like a clothes washing machine. The washer has electronic valves that open and close very quickly. The sudden snapping shut of the valve will cause a jolt of the water pressure in the line. This allows the pressure to escape into the tubes, rather than blowing out a weak joint or other damage to other fixtures.

>>904578
Fuck off terrierist.