Is it typical for the rough plubing (drainage and vent pipes) to bleed off pressure or is this a big concern. I failed the first plumbing rough inspection with 0 pressure (min 5 psi). I passed on reinspection at 6psi . After foundation beams were dug several days later, I was back to 1 psi. On friday I was at just below 5 psi. The plumber re-pressurized when he put in the water lines (which are holding pressure nicely). On Sunday I was back down to around 1.5 psi. Is this a big concern with rough plumbing drain lines or is it insignificant? Plumber is stating it is very typical and not overly concerned about it. Should I be pushing this?
Thanks in advance for your time.
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My experience on chasing down pressure-test leaks is that it's almost always the caps and temporary blocks used for the testing procedure. Check those first - I must subconciously think, "Oh, i've got to take this back out; I won't tighten it to death, or prime it well, or whatever.
Leaks even in a drain can be a lot harder to fix after the house is done and has spots . . . .
Another thing this time of year is temperature fluctuations making pressure fluctuations - just saw this is the attic I'm working in now. Pressurized it to 60 psi in the afternoon (75 degrees under the roof), 54 psi next morning (25 degrees); back to 60 by the late afternoon.
Forrest
I just have to ask: Did you "dry lab" those numbers?
If you start at 60 psi and drop the temperature from 75 F (534 Rankine) to 25 F (484 Rankine), the perfect gas law says the pressure drops to 54.4 psi.
(60 psi) X (484/534) = (54.4 psi)
Man, that's freaky! I actually wrote the numbers down on the stud; was worried that I was leaking. That's exactly what I wrote down.
Who new Redlich-Kwong could be so accurate!
Forrest - proving physics all over again
Here the drains must hold 5 psi. for 20 min. As was stated eariler, drain lines because of the size and nature of the pipe will fluctuate with the temperature.
If you passed at six pounds you are in great shape.
Do not under any circumstance increase the psi looking for a leak, this has on occassion proved fatal.
Man, I really appreciate the piece of mind. Since we are holding some level of pressure (5 psi to 1.5 psi) for 48 hrs, it is likely ok. It will hold 6 for several hours.
The plumber does not seem to be concerned. I was just worrying because we are adding stuff on top of it daily and will cover with concrete by Friday. It is approaching too late to fix it there was acutally a problem it seems.
Again, thanks for the piece of mind.
Just for your peace of mind, make up a soap solution and bubble test anything that looks a litte suspect.
As McPlumb says the leakage is generally at temporary caps, the inflatable or screw typt plugs, and at the threaded fitting were tair valve is installed.
Slather those areas with soapy water and look for bubbles. If you are still not convinced do a wet test. Plug all of the low pipes stubbed up and slowly fill everything with water, giving it enough time to not trap air. Mark the high water level on the tallest pipe stubbed up and check it the next morning. Look for where it may have leaked out. Don't expect it to be dead on the next morning though. You are going to trap some air as you fill it up, and it will find it's way out overnight.
We do wet test in my area all the time. It is what the inspectors want. They will do a wet test in the middle of the winter as long as they can watch it being filled up, and of course it is drained immediately. They don't like air test except on domestic water and gas supply lines.
Dave
man you are lucky you can use air.... we have to use water out the roof... cap and fill every DWV (block or cap line to sewer) I don't know the pressure but... with a 40 ft top out... and miles of pipe from 6" up.... you can only guess the pressure... btw i have 95lbs of water pressure from the city and it still takes 4-6hrs to fill....
we had a few temp caps blow before replace'n em with sch 40 caps... took 2 days to chase & correct leaks but we just got it passed last week...
on the water side all 98% pex... 3 main 1 1/2" lines... miles of red white & blue pex... fed thru a 3" back flow preventor... held 95lbs of pressure first try.... hae to love pex...
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