One for the LPG experts

[34127]

Hi all,
I have recently changed the gas pipework and fittings but on testing am getting a small leak. The gas connections were done by a ' gas safe' engineer but it didn't give me any confidence when he did the leak test for approx 1 minute and declared the system leak free. When I connect a manometer I am getting a fall of approx 10% over a 5 minute period. When you consider the volume in the pipework then this is a tiny amount of gas that is escaping.

I have tried to use a conventional spray on leak detection liquid on all the joints but nothing is showing up.
Would you expect a leak detector liquid to show up a leak of this size.

I have also placed a Honeywell EzSense gas detector directly below any fittings and left for some time and it does not alarm.
Would a gas detector like this be able to detect such a small leak.

Are there any standards for LPG testing that allows for a certain pressure drop over a fixed period of time

It is a possibility that it is the test manometer that has a minute leak but would need to get another one to prove this.

Any thoughts or comments would be most appreciated.

 

[Jimbohorlicks]

If you can pressurise your system you will find the leak

 

[andy63]

The test fluid or spray would show up any leak..it may take a while but even a tiny leak will show as a frothy spit around the area given time..

Don't know about the detector and how sensitive that is

The manometer is so basic I can't see you not been able to test right back to the connection point and the flexible rubber hose you use to connect it to the system ..if its good to there then the manometer will be ok..
Andy.

 

[Raul]

What pressure did you test at? You can test with pressurised air before you release the gas. Some say to test at regulator pressure, but, I found some guidelines that mentioned testing at 5 times the working pressure. Greg Virgoe on one of his build videos, brings this up, about the gas installation on a van.

 

[34127]

I am using an electronic manometer that had good reviews but wasn't expensive so not 100% confident about it being leak free.

I have pressurised the system and tried different pressures and also the standard gas pressure and there isn't a great deal of difference in the decay rate, slightly higher decay at higher pressure as you would expect.

I would have expected the leak spray to show up leak but as no experience of using them don't know what the limitations are with using it.

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[vantastic]

I was a bit concerned about gas leaking as well so I was checking out those cheap gas meters on Amazon. I think the consensus is they do work rather well but take a very long time to detect the leak.

Consider the leak may be in an appliance rather than a joint. Can you divide and conquer? As in, have you any valves you can turn off to make the test area any smaller? It might help rule out some joints at least leaving you focus on the remaining ones.

 

[34127]

..

I was a bit concerned about gas leaking as well so I was checking out those cheap gas meters on Amazon. I think the consensus is they do work rather well but take a very long time to detect the leak.

Consider the leak may be in an appliance rather than a joint. Can you divide and conquer? As in, have you any valves you can turn off to make the test area any smaller? It might help rule out some joints at least leaving you focus on the remaining ones.

I can isolate all the appliances and am only testing the pipework and isolating manifold valves. I have tried a pressure test on digital manometer only and the pressure is still dropping slowly but considering the extremely small volume of air in the tubing to the manometer then the leak could be minuscule and insignificant.
I was hoping someone with LPG knowledge and experience could have voiced an opinion about this.

 

[Raul]

You have to take it step by step. Isolate the regulator and the manifold to the appliances. Test the line, then, if all good open on the manifold one at the time. You pressurise, wait for 5 mins for the temp to even, then take a reading. There is a standard for motorhomes and caravans, but you have to pay for it. If you want to find out the relevant content, search for Greg Virgoe on YouTube. He has a build channel, and in one of the episodes describes the lpg installation in detail. Very helpful. He quotes and follows the standard EN xxxx, that is most up to date.