Testing with air

JH

During cold weather, some people switchover to doing their pressure testing with air. Can the testing pressures be reduced when using air? If so, is there some written justification that might satisfy organizations like the Corps of Engineers.

steve gates

depends

I test water and heat @60#. soil %5#

GMcD

Testing with air

We specify an air test (usually 100 psig), and hold that pressure, with air, during cold installation of radiant tubing. This would apply to any kind of hydronic piping unless the building/space where the pipe is has temporary heat. The risk is too high otherwise. A recent incident here drives that home: 8 storeys of concrete core conditioning (radiant slabs) system, contractor elected to leave the water in the radiant tubing over Christmas break, got cold, the pipes froze, blew out in many locations and spalled out concrete in over 85 locations, plus created linear cracks along the tubes. Some of the exposed concrete ceilings were already painted and finished....not nice, especially in a seismic zone where the slab integrity is critical....The Contractor was likely trying to save the cost and time of draining and re-filling the system and gambled. The other solution to this would have been to anticipate that temp. heat would not be available, and fill the system with an antifreeze mix, a small cost versus the consequences....Think ahead....

Alan(CaliforniaRadiant)Forbes

The code

specifies a hydrostatic test because it's safer than an air test (air will compress where water won't), so if you do an air test, you've got to be careful: someone might get hurt.

Make sure everyone on the jobsite knows what's going on and that if the tubing breaks, it'll be like a bomb blast.

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Arthur

Funny story

We were doing an installation for chilled water using black pipe with welded fittings mostly 2" pipe. we had pumped the system up with compressed air to about 70psi. I happened to be away at the time But the welder I had (who should have known better) found a leak on a welded joint (We use a soapy spray to find leaks) and put the gas torch on the joint without dropping the pressure, He got it nicely red hot and then bang it blew out in a big way. There was about 1/2 dozen tradesmen electricans, chippies, painters etc and apparently the building was cleared with a great stampede out the door.
Some thought it was a gas line but there was no gas in the building, We still laugh over it. Wished I'd been there mind you I would have got the pressure dropped if I had've been.