Advice required on air testing Polyplumb pipe

[Plucky]

Having a bit of trouble at the moment at work. Basically got 24 rads plumbed in 10mm polyplumb. Each with a flow and return going back to 2 x 12port polyplumb manifolds. Under each rad the flow and returns go into a 10mm x 15mm reducer, into a 15mm elbow and through the floor in 15mm copper. Each rad tail is capped off with a speedfir stop end.

The house is now being drylined and pipework is slowly being hidden in floors. Trouble is on an air test I am losing pressure. I pumped it up to 3bar and it dropped quarter of a bar in about 16 hours. I have found every single joint and sprayed them with LDF and nothing. Taken nearly every fitting apart to check all bits were in tact. Cant find this leak anywhere.

A colleague of mine has mentioned that he things an air test on plastic pipe is no good and that when the system is full of water that it would be OK. Anyone else got any views or advice.

I dont really want the ceilings plastered etc only to find it still leaks with water when the system is commisioned.

 

[dontknowitall]

I've learned that if you pressure test with water in the pipes you can expect a drop in pressure (due to the water contracting under pressure?)

I wonder if the plastic has expanded a little under pressure and, with a large system as you have, whether that equates to the 1/2 bar drop.

If it was me I'd be happy with that test (assuming the final pressure will be around 1-1.5 bar). If there was a leak I'd expect the pressure to be nearly 0 after 16 hours.

Another thought ... was the pump attached all the time or did you take it off? I use a bicycle pump (standing up one) and remove it after applying the pressure as the valve can often leak a little when it's still attached.

 

[bobpape]

Down "TO" a quarter of a bar..

or "A" quarter of a bar

 

[dontknowitall]

I read it as dropping from 3bar to 2.75bar.

As to why I said 1/2 bar drop I'm not so sure!

 

[so-solar]

why are you not wet testing the installation?

 

[stevetheplumber]

Having a bit of trouble at the moment at work. Basically got 24 rads plumbed in 10mm polyplumb. Each with a flow and return going back to 2 x 12port polyplumb manifolds. Under each rad the flow and returns go into a 10mm x 15mm reducer, into a 15mm elbow and through the floor in 15mm copper. Each rad tail is capped off with a speedfir stop end.

The house is now being drylined and pipework is slowly being hidden in floors. Trouble is on an air test I am losing pressure. I pumped it up to 3bar and it dropped quarter of a bar in about 16 hours. I have found every single joint and sprayed them with LDF and nothing. Taken nearly every fitting apart to check all bits were in tact. Cant find this leak anywhere.

A colleague of mine has mentioned that he things an air test on plastic pipe is no good and that when the system is full of water that it would be OK. Anyone else got any views or advice.

I dont really want the ceilings plastered etc only to find it still leaks with water when the system is commisioned.

not sure you can air test plasic as it will pass some air through the fitting although it wont leak water 16 hours is a bit excessive as well 30 mins is plenty i do air test but more to make sure theres nothing drastic like an open end

 

[Plucky]

It had dropped from 3 bar to 2.75bar. The reason we are not possible to test wet as we are in a remote location with no mains at the moment. The 16 hour test was simply just being left from overnight until I returned the next day.

Im going to try and find someway of filling the system with water.

 

[Bernie2]

Hi! Plucky

Hire a hydraulic testing manual hand pump with a reservoir. You just pump water in, bleed air out and you pressure test the same as any other pressure test. Its fairly straight forward for copper pipe and the like but a bit more complicated for plastic.

To save me writing it out, try the UK copperboard website there is a good article by Brian Curry called Pressure Testing Piping Systems.

That way you can quote a recognized reputable source for your procedures beside Water Regulation 12.

The reason I say that, is simple, if you get into aggro later on, say for a leak, you can prove you followed a recognized procedure. It may not stop the aggro, but it may lessen it a bit.

 

[justlead1]

Hi If you leave the system on test, for long periods say over night the temp drop will have an effect on the pressure you recorded initially. When testing with air. Good Luck

 

[migoplumber]

nothing wrong with an air test, i do regular and take them to about 3 bar, remember compressed air is quite dangerous, read manuals well and be careful.

after the air test to prove nothings gonna pop, then do your wet test, really usefull on plastic pushfit as it expands the pipe and makes the gripper ring in the fitting really dig into the pipe.

 

[Plucky]

Bernie we have a test bucket but the issue is lack of water on site until mains is connected in.

Anyhow traced the drop to a section of pipe and took all the fittings apart for inspection. Didnt find anything but put it all back and it was all fine for 1 hour.

I have left it on overnight and will see what it reads in the morning. Hopefully it was just a bit of grit or something.