plumbcrazy, a word of advice on an air test for dwv. on a small system no problem. on a 200 unit apt. building 6 stories, good luck. sounds simple until you need to locate a leak. dripping water easy to locate. dripping air, good luck:confused:.
can't say it can't be done, but at a certain point it's a drag. remember a large system will take a long time o show a pressure drop on a small leak. sort of like a nail in a wheel barrow tire and a nail in a big truck tire. the wheel barrow will go flat real fast. the truck real slow.
I couldn't agree more Rick. I myself rarly use an air test, I was just giving him the legal options.
The other concern is the danger is pumping all the potential energy (air pressure) into the piping system. for materials that can shatter or crack, this is not a good idea (brittle materials like Cast Iron, PVC, etc), because if you have ever seen a PVC pipe blow up with 15 or 20 PSI of air in it, you wouldn't want to be anywhere near it. Unless you clear the building of all personnel, you never know who could be in the wrong place at the right time. :(
I remember doing an air test on a large hotel complex some years ago. We did it in sections of course but still we were pumping up a couple thousand feet of copper up to 4" diameter at a time. The high rise hotel tower sections were done three floors at a time (32 hotel rooms per floor IIRC).
We used a large compressor like you would need to power a couple jack hammers, don't remember the size but it was powered by a 6 cyc engine. It would take about 20 minutes to get to 30 PSI using 1" hose, then we would hold that for a while (drop test) and go hunt down any leaks; this was our internal test before presenting to the inspector. We were looking for leaks, marking any that we found, then go back and fix them.
With a work force of roughly 120 plumbers and fitters on the job, and people coming and going over the duration of the job, it was important to monitor the quality of the work. Ya know, some guy gets ticked off because he didn't get to work OT and someone else did, or they are getting laid off the end of the week, so they 'get back' at the contractor by 'fixing' a few things for them before they leave (yeah, believe it or not it happens :) ) , or someone just plain forgets to solder a joint or its in a tight spot and they leave a pinhole or you've got a bad fitting (it happens even with copper fittings, though rare).
Any one of these can do expensive damage if the system is not checked before putting water in it. Once we got a good drop test with air we would go back and do a water test for the inspector.