Pressure tests

Hi,

This may sound like a silly question but...

Is water pipe expected to be gas tight as well??

I have been doing some air pressure tests with an air compressor on the first fix plumbing, the pipe is plastic with compression fixings and all pipe runs are terminated with isolating valves. approx length of pipes is 70m of 1/2" and 60m of 3/4". I have pressureised the pipe to 6 bar and this found a few faults (some loose compression fixings and a couple of manufactoring faults in the pipe:( ), having fixed those the pressure only holds for a while, 30-45 minutes .

Regards,

Philip

CJhaughey

Is your testing apparatus able to hold pressure?
The reason I ask is because I did the same myself, and the gauge wouldn't hold pressure for long, you need to be able to isolate the gauge and associated pressure from the compressor and hose.
usually a ball valve will do the trick.
I tested all my plumbing with this and it tested fine but it didn't pick up the poor pushfit connection upstairs in the 3/4 Qualpex which blew off after a month of having pressure in it.
Luckily there is a floor trap in the utility that allowed the water to escape before it damaged the rest of the house.
I think the spec for qualpex is 4 bar for 2 hrs or something like that, but leave it overnight if you can.
Make a small length of pipe up with a stop and check that the gauge works with this small closed system.

CJhaughey

Thanks for info.

Yes I have a ball valve between the system and the compressor (and gauge),
Not ideal, just happened to be the way I assembled the test system, I will swap around the parts and try again

CJhaughey wrote:

I tested all my plumbing with this and it tested fine but it didn't pick up the poor pushfit connection upstairs in the 3/4 Qualpex which blew off after a month of having pressure in it..

That's why I decided to use compression fittings, heard too many stories about push fit ones.

awishawash

Sorry to butt in lads, just wondering where I can get a compressor for that. Would give me alot of piece of mind before turning the water on! Can it be used on bigger pipes aswell like waste and that?Heard of smoke matches but you cant beat a bar test.

I got mine off Ebay, cost £70. I originaly got it for driving an air nailer, so it was just available for pressure testing.

http://cgi.ebay.co.uk/SIP-COSMO-1-25HP-COMPRESSOR-AIR-KIT-NAILER_W0QQitemZ300027335234QQihZ020QQcategoryZ22662QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

As for pressure testing large diameter/long runs, not sure but I expect it would take a long time to get up to pressure, for soil pipes you would probably only need to go up 0.5 bar. I wouldn't expect it to be airtight.

CJhaughey

I used the 1hp compressor that I got with my finish nailer from senco.

awishawash

Cool I'll have to invest!Thanks

Thanks CJ,

I changed the layout of the test setup and fitted the gauge further down the system where a washbasin tap will eventually go, and a valve between the compressor and pipework. pressurised the system to 4 bar, still drops after one hour:mad: so tightned up suspect compression fittings, no joy:( .

Decided as I was unable to hear the escaping air, I filled the system with water, and then pressurised to 4 bar, the majority of the compression fittings weeped :eek: :eek: I had committed the cardinal sin of overtightening the fittings:o have spent the weekend applying PTFE tape to all the fittings repeated the test to 6 bar Monday afternoon, still at 5 bar tuesday morning, 4.5 bar two hours ago. just one wet joint, will fix that if pressure drops below 3 bar.

Pataman

As far as I remember plumbers only pressurise it to 3bar, mains pressure generally 2bar