Vacuum breakers

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Rich Feldman
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Vacuum breakers

Post by Rich Feldman » Thu May 24, 2018 9:03 pm

What this has in common with fusors is vacuum and leaks.
My house water pipes had a persistent leak that got as bad as a cubic foot per day.
Until yesterday, when a crew removed the 60 year old galvanized pipes, and replaced all of them with copper.
The job included some apparently unnecessary details to please the city inspector, since this job was done with a permit.

Every outdoor hose bibb, including one unrelated to the repiping job, now has a vacuum breaker. Those are required by code, as protection against a rare but catastrophic event: water main pressure going negative (sucking) at the same time somebody has a hose running with the end in a filthy puddle or a pesticide-mixing container.

I knew about these but had never seen one. They are short extenders with female and male garden hose threads (untapered 1 1/16 - 11.5).
Screwed on tightly and then locked with a setscrew:
DSCN0436.JPG
Pictured above is the one specimen where they forgot to tighten the setscrew until its head torqued off. The others look like this:
DSCN0435.JPG
I think the idea is to deter casual tampering. Policy makers expect that most consumers will be OK with using their hoses on vacuum breakers. Maybe I will do a maximum-flow test on the faucet in upper picture, with and without the doohickey, before the second visits by contractor and inspector. (there's drywall and plywood to be patched).
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John Futter
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Re: Vacuum breakers

Post by John Futter » Fri May 25, 2018 7:54 am

aaaaah
fixing a problem that could exist on a 1,000,000,000,000, : 1chance of somebody actually usinng a hose when a negative pressure event caused by alien invasion is taking place.
I'm glad your city has senior idiots empowered to think of of all these implausible happenings - this of course after they have removed gun ownership from the plebians

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Rich Feldman
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Re: Vacuum breakers

Post by Rich Feldman » Sat May 26, 2018 5:16 am

By the way, the expensive repiping job didn't stop my mysterious cubic-foot-per-day leak. :-( It did stop the liter-per-day seeps and oozes for which there was plenty of evidence in the old pipe plant, and tedious water meter watching records.

Fortunately, all the new valves actually close properly. Made it easy to locate the "big" leak. Improbable combination of leaky toilet tank flush valve, a float valve whose hysteresis often fails, and a shutoff valve that didn't fully shut. It has an equilibrium state with tank silently draining into bowl, while a matching flow silently enters from the water supply line. I'd foolishly dismissed the toilet as source of problem, because the leak rate didn't cycle on and off. ref: time lapse recordings of water meter dial.
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Richard Feldman

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Rich Feldman
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Re: Vacuum breakers

Post by Rich Feldman » Tue Jun 05, 2018 4:55 pm

Some old sprinkler valves (with more vacuum breakers) started to exhibit Bourdon-tube-like behavior
after the repiping exercise.
You can see it on video, if this link works. Then scroll to the next video for explanation.
https://www.flickr.com/photos/r_k_f/416 ... 025260349/
DSCN0521r.JPG
They're in the same album as my old shock diamond images.
Richard Feldman

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Rich Feldman
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Re: Vacuum breakers

Post by Rich Feldman » Fri Jun 08, 2018 10:58 pm

Just learned that those telescoping PVC repair couplings are supposed to move freely, unlike my original union with O-ring face seal. Duh!
The smoochy valve problem went away when the pipes below the coupling were restrained.
Repiping contractor, here to fix an unrelated problem, did that by putting dirt in the hole.
Richard Feldman

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