Testing water pipework for leaks, prior to first use??

I used compressed air (compressed with a bicycle pump) and looked for pressure drop and checked joints with gas leak detector spray.

BIG WARNING: This is really dangerous though. If some part of the system fails, the energy stored in the compressed air could have brass fittings flying around like bullets. For amusement value, I released a JG pushfit endcap after testing a section of plumbing. It probably ricocheted off the walls floor and ceiling about 10 times before it slowed enough for me to see it, and I was deaf for an hour or so from the noise of the air rushing out.

What you're supposed to do is fill with water with just a little air to pressurise it, but once you've got the system wet, resoldering any joins becomes harder. Also air leaks much faster than water, so if it's airtight, you know it's even more watertight. Leaking air doesn't damage any furnishings either. Even the gas leak detector spray is specifically non-staining to furnishings.

If you do an air test, probably best to make sure there's no one else in the vacinity of the plumbing, and no kids in the house at all, in case something goes bang.

leak detector spray - how's that work then?

Jim K

It's generally a soapy-type stuff - spray it on a joint and if bubbles appear you've found your leak.

... but someone near enough to come to the rescue.

It's a fancy version of washing up liquid solution, except not corrosive (unlike washing up liquid, so no harmful residue left when it dries), it grows much smaller bubbles so you get clumps of what looks like white cuckoo-spit, and it seems to have a penetrating oil like ability to get right into connections, even when that means flowing up.

The one I usually pick up from local plumbers merchant is called LD90 in an airosol can with an internal weighted takeup so can works at any angle.

Cap the open ends off and try one of these...

of air pressure testing, as mentioned by an earlier reply.

Lee Nowell wrote in news:621774a9-2177-4c62-a768- snipped-for-privacy@v41g2000yqv.googlegroups.com:

Thank you - that looks like a very functional solution. I was tentatively hoping someone would have a method that doesn't cost as much. But at the end of the day, I suppose it might be better to spend £29.88+p&p rather than risk the damage that a water leak could cause.

Al

snipped-for-privacy@cucumber.demon.co.uk (Andrew Gabriel) wrote in news:i43caf$3mi$1 @news.eternal-september.org:

Thanks for the input. What method did you use to test for pressure drop?

Al

I hired a water pressure pump and meter for a couple of days for a fiver from the builders merchant.

It's diluted fairy liquid, it bubbles where a leak is allowing gas to escape

I have written on this subject before.

If the leak detection fluid is applied to a joint and the leak is big enough to blow the detection fluid away before forming a bubble, then you fall into the trap of assuming there is no leak.

I have used the following way to detect leaks in all sorts of dangerous gasses from CO2 through oxygen, to hydrazine (rocket fuel.) Once you get as far as oxygen, then you can't use normal soaps and have to change to something that is less volatile when mixed with the gas.

To test a low volatile gas pipe for leaks, after pressurising the pipe, take a small container full of the fluid and with a brush try to create a collar of small bubbles all around the joint. If you find you can't do this, suspect a leak and investigate. It will be the leak blowing the detection fluid out of its way.

If you get a collar all around the joint, examine closely with good light and a mirror to see if there is any growth in the number of bubbles. If there is, suspect a pin hole leak and investigate. If the collar is stable, or the bubbles are slowly popping away, but leaving a full collar behind, then you have a sound joint. The observations should be taken over about a minute.

Nearly forgot, if checking a compression joint, bubble up everything from before the first nut to after the second one. A leak can occur anywhere in-between the two pipes.

HTH

Dave

I've used one of these for the same purpose, with appropriate adapters: seems to be essentially the same, but a helluva lot cheaper:

David

I would have thought just putting an inflated balloon over an outlet would have told you enough.

Ah, but sprays are already full of bubbles. Even when one uses detergent solution it can sometimes be difficult to tell which bubbles are from a leak and which you just made when you squirted.

Just do a tightness test as for gas work i.e. up to 20mbar or so with a manometer (which you can make yourself with winemaker's tubing if you're not already kitted out). Use an airbed inflator (manual) or bicycle pump (carefully) to pressurise. If that holds with no drop over several minutes then pressure test with water at mains pressure (which is typically 2 or 3 times as much as you'll be running at for central heating.)

The advantage of the air test gauge is the valve, both for attaching a footpump and letting down the pressure gently - though that doesn't explain the price difference.

When using either of them for repetitive testing, you need to make up a set of adapters to pipes so the the gauge joint doesn't get worn/ damaged by repeated cycling.

Dry Pressure Tester:

I've had it some years now, and I've had to replace the O ring seal. Buy a handfull of 15 and 22mm JG pushfit endcaps too, for sealing. Also, the 15mm ones are the same O ring when the Dry Pressure Tester's one wears out.

When I was doing the heating, I was only in the house at weekends to work on it. I usually left a new section of circuit pumped up over the week and checked if it lost pressure next weekend. Probably not such a good idea if the house is occupied at the time.

I originally intended to pump up to 3 bar, but a) It occured to me how dangerous this is, b) pumping up a circuit which includes, say, 2 radiators to 3 bar with my punge type bicycle pump was killing me (much harder than pumping up a bicycle tyre to 3 bar). c) because air is orders of magnitude less viscous than water, it leaks orders of magnitude faster, so leaks which you'd never notice with water with still get found and fixed, even at lower test pressure. Usually went for 1 - 2 bar -- enough to blow apart any missed joints.

Let the pressure out by depressing the valve pin in the tester, or a radiator bleed key, not by opening a pipe or any other sudden release method.

Just finishing adding to/altering my CH system, so lots of remade compression joints and about 20 new solder joints. This topic came up at just the right time.

Now, it's a combi boiler so made to run at 1 - 1.5 Bar, with a max. of 3 Bar. Would it be reasonable to pump up the system to about 2.5 Bar and use the boiler's gauge to monitor the pressure? I've a track pump that can manage about 6 Bar into a tyre in about a dozen strokes, so shouldn't be to onerous for 8 rads. Apart from the relatively large amount of air at low pressure (rather than the small amount of expansion of water normally present) the system will be within its design pressure, so would pressurising the boiler with air instead of water cause any damage? It'd certainly be a cheap and easy method :-)