"Ed Sirett" wrote in message
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On Sat, 02 Dec 2006 13:27:25 +0000, Doctor Drivel wrote:

"Andrew Gabriel" wrote in message
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In article ,
Moz writes:

About 40 years ago my Dad pressure tested a DIY plumbing installation
using a car tyre valve (soldered somehow into a 1/2 inch BSP
compression fitting), a foot pump and a car engine compression gauge.
After filling the system with compressed air he left it overnight and
checked for pressure drop.
Does anyone know if this would be an appropriate way to test a plastic
(JG Speedfit) central heating system prior to filling (the gas fitter
is coming to fit the boiler on Tuesday)? I can seal off the open ends.

Yes. You can buy an adaptor with a 15mm pushfit, a tyre valve, and
a pressure guage, e.g.
http://www.screwfix.com/app/sfd/cat/...10179&ts=53191

It's much easier to dry test in sections than it will be to do the
whole system at once, but if you've already constructed it all, I
wouldn't bother breaking it apart now. It takes a lot of effort to
pump up even a couple of radiators to 2 bar, and I wouldn't dare
go that high with a whole system, as the energy stored in it will
be massive -- if any part does break apart it will fly apart
explosively (release the pressure gradually when you're done, from
something like a bleed valve, not by pulling apart a fitting;-).
The relevant British Standard recommends evacuation of the
building when pressure testing pipework with air.

I would suggest getting a can of gas leak detector spray too.
You spray this on all the joints and it will give a much faster
and more accurate indication of any leaks than will watching for
a drop on the pressure guage

High pressure escapes will not blow bubbles.

But they can easily be heard, instead.

Depends on the pressure and the size of the hole.