air test vs water test

Now that the plumber is gone & I have finished the laundry hookups we are ready for the city plumbing inspector to come through next week. When talked to him on the phone I told him that we (me & plumber) would do an air pressure test @ 80lb; however he said it really wasn't necessary, that just doing test with water on would be fine. The plumber said he preferred an air pressure test and would come back to do it.

So my question is, other than having to drain water if there is a leak, are there any other advantages of an air pressure test over water test?

Thanks,
Matt

 

Air tests are usually tested at a higher PSI (I've seen systems tested at 130-150, your house may have anywhere from 30-80 PSI in the water lines. Less to cleanup if there is a leak with air though.

 

If the pipes have never had water through them, it's easier to fix a leak. Sometimes, you could probably just reheat and add a little more solder. But, if it didn't flow well, it may not have been cleaned and prepped well, so taking it apart may be better. If you do a water test, you don't have a choice, you must take it apart, clean, then resolder. that can be a pain if things are tight and you can't spread the pipes enough. My guess is it's probably easier to hear an air leak than maybe spot a drip, but that's just a guess. Course, your hearing has to be good.

 

testing with high pressure can be a safety issue so be careful if you do it that way. I worked on a job where we tested with air because there were a lot of "traps" the way the pipes ran. Pumped the lines with 50lbs of air. one of the plumbers heard a leak but it was hard to tell exactly where it was coming from. He went to feel an elbow and it blew apart, not soldered at all. had to bring him to the hospital for stitches as the pipe whiplashed and caught his hand.

 

The plumber told me it would be easier to fix also if was an air test but, he did not tell me why. He said he would fix any leaks on the work he did (he is very confident there won't be any). Do not feel right asking him to fix leaks on the plumbing I did. So now I am curious as to the mechanics of fixing a leak found via air test if one does occur in the laundry area plumbing that I did?

Thanks,
Matt

 

air test done

Ok, did air test and pumped it up to 80 psi. Evidently there is a slow leak somewhere since lost 4psi in 13 minutes on the pressure test of the whole system. Then when did test on just section between meter shutoff and the ball valve inserted in new supply line after meter, lost like 4psi in about 4 minutes. The pressure gauge is in between meter shutoff & new ball valve. Weird losing more psi quicker on just the small section (4') vs whole system.

So now get to start the fun process of figuring out location of leak(s). There is a small leak from water meter even though water is off. The city inspector said water pressure in city is around 50psi. Is it possible that the much higher 80psi test pressure is going back through the meter into the line through the known slow water leak from meter shutoff valve (old turn handle style).

Figured I would start with valves first - have total of 15 Nibco ball valves in system - maybe the nut on control stem needs to be tightened on one or two. Obviously I am hoping it is something relatively simple.

Any special solution, other soap/water mixture, used to test joints, etc. for leaks?

Thanks,
Matt