Gas Testing

[rudeboy]

I intend to use an existing run of 15mm copper to supply bottled propane to a hob - roughly 10m. The pipe run was installed to supply a fridge but never used. The hob will be re-jetted and installed by a CORGI installer as well as the gas changeover valve to switch between 2 bottles located outside.

I want to fit some cabinets which will make part of the relevant piping inaccessible. How can I go about gas testing the existing pipework before the gas fitting is completed? If I can establish the existing copper is gas tight, this will hopefully minimise the need to access the joints hidden by the cabinets.

Thanks

 

[petit_pablo]

You cant really, would need a RGI to tightness test installation.

That said, it could be air tested if the gas is disconnected.

 

[gas4you]

New LPG pipe work should be air tested before any tightness testing.

 

[rudeboy]

Thanks guys. I think air testing is probably what I had in mind, there's no connected supply yet, its open 15mm copper at both ends.

how exactly is an air test performed and what equipment is needed?
What is tightness testing? Sounds like taking your plumber out for a drink to see if he parts with his cash!

 

[billy bob]

If you do not know how to carry out the test, or what equipment is required, then you should not be attempting to do it, you are obviously not competent to do so, I am not having a go, but as the law stands, even a DIYer must be competent to carry out any gas work on their house, but you do not know how to carry out the procedure, so are not competent.

I think all proffessionals on this site should refrain from explaining the test procedure for gas.

 

[rudeboy]

Right on Billy Bob, in the most part I agree with you.

I am a more than competent plumber, and have every confidence I could complete this work with NO testing at all. HOWEVER the slight risk of killing my wife and kids is my incentive to have the job done by a pro.

That said, I think you are missing the point here. It's not the gas work I'm doing - I'm simply fitting some cabinets. So chicken and egg situation: Mr CORGI needs the hob to be suspended in a cabinet. Cabinet(s) when fitted will obscure 2-3 joints which may or may not leak when tested, so common sense dictates it would be prudent to know the pipe is airtight before fitting the cabs. The same applies to checking a cable for continuity, or a waste pipe for blockages and I don't think anyone making these checks would be claiming 'competence'.

All I want to do is isolate one end of the pipe and apply pressure in some manner at the other. I don't know the kit, or the terminology - maybe someone could help me out here??

 

[doitall]

As a Competent DIYer I will tell you what to do

Slide a roll of 10mm through the middle of the existing pipe = no joints

 

[rudeboy]

Cheers, a solution at least. One I would only be inclined to explore if there was significant risk of a failure. Also I may come a-cropper trying to squeeze the 10mm around elbows.

Another consideration is throughput. As this is a longish run, I believe I need 15mm to deliver enough gas to the hob.

 

[Terrywookfit]

In these circumstances I would call and first fix the gas supply test etc!!

I then know the installation is compliant!!

 

[doitall]

10m + 2 elbows and a valve will deliver 10.84 Kw or 0.42M3/hr, more than enough for most hobs.

Alternatively you could use 12mm and sleeve it through the wall.

You will need to leave the pipe/sleeve exposed where it goes through the wall, so the RHI can check and seal with flexible mastic.

LPG is not an DIY job and should not be treated as such.

Pre-test is 1.5 x maximum pressure e.g. 9bar

 

[Agile]

Pre-test is 1.5 x maximum pressure e.g. 9bar

Assuming this is to be supplied AFTER the regulator at the cylinder then surely the tightness test should be based on 37 mB ???

Tony

 

[doitall]

Pre-test is 1.5 x maximum pressure e.g. 9bar

Assuming this is to be supplied AFTER the regulator at the cylinder then surely the tightness test should be based on 37 mB ???

Tony

No Tony, the tighness test is 1.5 x vessel pressure.

37mb is the operating pressure after the second stage regulator 55mb, without appliances connected.

 

[Terrywookfit]

Pre-test is 1.5 x maximum pressure e.g. 9bar

Assuming this is to be supplied AFTER the regulator at the cylinder then surely the tightness test should be based on 37 mB ???

Tony

No Tony, the tighness test is 1.5 x vessel pressure.

37mb is the operating pressure after the second stage regulator 55mb, without appliances connected.

Low pressure installations should be tested with air @45mb!

NO drop allowed over 2 min period!

Boats are tested at higher pressure!

 

[doitall]

Yes, sorry I'm thinking of Bulk tank and service pipework intended to operate at 0.75 mbar up to the second stage regulator. which would be a test pressure of 1.125bar.

 

[kirkgas]

i don't do LPG so can't comment on the testing, but that aside any good gas guy would not be happy to connect and sign off a pipe he hasn't fitted/inspected ( ie you test, fit cabinets and then call him in) even if he tested successfully himself after the units he hasn't confirmed as visually safe, he still could not guarantee that it was properly fitted and sealed, you say there are joints on the pipe but we don't know how they are sealed, i would suggest a gas guys visits changes pipe and tests, you fit cabinets and he returns and connects hob and tests again everyone is happy that everything is done properly and we all sleep well.