Pressure testing new plumbing with air

[islandboy]

Hi,

 

Does anyone have any experience of testing new plumbing with air? All I can find online about it is don’t! Im hoping to ensure that the pipework is leak proof before going any further. 

If anyone has tested their plumbing with air, can they advise to what pressure they took it and how long they held it for?

 

Many thanks

[Vijay]

I've done it before an didn't have any issues, left overnight. Why have people said not to?

[Big Jimbo]

I always prefer to do it. Id rather it leaked air than a load of water. I normally test at about 4bar. Higher than the crappy water pressure supplied to my house. I usually leave it for an hour.

[SteamyTea]

The reason that air is not used is for safety.  Air expands, water/oil does not.

[MJNewton]

1 hour ago, SteamyTea said:

The reason that air is not used is for safety.  Air expands [...]

 

...which in case you were still wondering 'so what?' means that it therefore stores energy (when compressed) which can be dangerous if something suddenly gives. Shouldn't be an issue with low pressure plumbing testing though I wouldn't have thought. (I have visions now of an AAV blowing a hole in the roof and landing in next door's garden...)

Edited September 25, 2020 by MJNewton

[nod]

14 hours ago, islandboy said:

Hi,

 

Does anyone have any experience of testing new plumbing with air? All I can find online about it is don’t! Im hoping to ensure that the pipework is leak proof before going any further. 

If anyone has tested their plumbing with air, can they advise to what pressure they took it and how long they held it for?

 

Many thanks

I pumped air into the UFH

as I was worried about the pipes freezing if I’d used water 

It held six bar of pressure for about six months 

[Temp]

With air you need to loose a lot to see a reduction in pressure. With water not so much.

[Nickfromwales]

4 hours ago, Temp said:

With air you need to loose a lot to see a reduction in pressure. With water not so much.

And water is obvious in seconds. Shows itself vs you having to go around every inch of pipework with a leak detection fluid.
PITA vs water. ?. 
FYI Water testing shows a leak WAY before you get to even 0.5 bar so doesn’t need to be spraying everywhere and causing ‘mass devastation’ so don’t fear that. A bit of blue roll and some mopping up is the worst that’ll happen. I’d rather see the problem there and then and get it identified and dealt with, and that’s been the method I’ve used for the last 25 years. Commissioned a system last week and pinched 2 drips up whilst pressurising.

Drama = zero. 

Edited September 26, 2020 by Nickfromwales

[Carrerahill]

On 25/09/2020 at 20:23, Vijay said:

I've done it before an didn't have any issues, left overnight. Why have people said not to?

You are not meant to pressurise water pipes with air because of the risk if something does let go, air is highly compressible, water is not, therefore if you pressurise a system with air then you will have far more of it than you would water, i.e. just the volume of the pipework with water, with air you can multiply it by the pressure. 1 litre of capacity at 2 bar is 2 litres of air (note compressibility of air changes as pressure increases, however from about 0 to 10bar it is about a factor of 1), I'd say you need to pressure test pipework at a little over local water pressure, so when I air pressure tested my pluming I ran it to 4 bar, I don't know the exact capacity of the pipework but I reckon about 15 litres for the runs I was doing, so I probably had about 60 litres of air contained in that pipework, imagine that then let rip at a loose connection, could take your eye out or worse! Also, arguably you could test at 2 bar because if it is going to leak it will probably leak at less then 2bar to be honest, but I was being naughty, however I also felt that going to 4bar would also show more clearly if there was a drop as air can leak out the smallest of holes at a very low rate.

 

I made a pressure test rig with a inline pressure valve and 2 isolation valves then a Schrader valve that let me use my air compressor, I could then isolate the inlet and leave the pipe under pressure over night and check for a drop, I took the risk, which for my test situation was deemed minimal because all the runs were under the floor.

 

 

Edited September 28, 2020 by Carrerahill

[Carrerahill]

On 25/09/2020 at 19:58, islandboy said:

Hi,

 

Does anyone have any experience of testing new plumbing with air? All I can find online about it is don’t! Im hoping to ensure that the pipework is leak proof before going any further. 

If anyone has tested their plumbing with air, can they advise to what pressure they took it and how long they held it for?

 

Many thanks

I did it, I took the risk to be honest and I know the risks and understand the reasons why I should not have done it, I actually believe if you MUST undertake air testing you are meant to display warning signs stating that air pressure testing is underway - that is how dangerous it is deemed.

 

Think pipe-bomb basically.

 

I did my pressure testing in an empty house, my house for that matter, and I undertook it with mitigation measures in place.

 

I had to bury pipework that would not go live for months after it as buried, I sure as heck was not going to bury it without knowing!

 

 

[Carrerahill]

On 25/09/2020 at 21:42, Big Jimbo said:

I always prefer to do it. Id rather it leaked air than a load of water. I normally test at about 4bar. Higher than the crappy water pressure supplied to my house. I usually leave it for an hour.

Same here, only I left it overnight.

Edited September 28, 2020 by Carrerahill

[Hobbiniho]

As nick has said when using air you would need to spray every joint with leak detect spray (soapy water) simply leaving it for an hour and measuring the pressure drop isnt sufficient.

 

I do a lot of pressure testing at work, both hydrostatic and with nitrogen i much prefer hydrostatic as it only takes a small leak for the pressure to drop and is easily seen, in a domestic situation im not really sure why you wouldnt use water considering the relatively small volumes involved and the added danger with using compressed air, i wonder if the manyfacturer rates their equipment for pressure testing with air ?