Gas testing question

[heatho87]

Just doing level 3 now at collage, just a stupid question realy if you installing new pipe work to some older gas pipe work on a tightness test you are allowed 0.4 mb over 2 mins of test does it only go by that 2 mins anything after is fine as along it doesn't drop no more that .4 mb in them 2 mins also if there is a drop were does it usally come from appliances ?

Thanks

 

[jdstratton@btin]

I am not gas safe registered but have done some training in the past . Believe your allowance is as you say .4 mb in two minutes . You could have another .4 mb in the next two minutes . Believe the loss comes mainly from old appliances . Having said this I would want to check the pipework alone to be sure the loss is coming from the appliances . No doubt a GSR person will come along to clarify .

 

[beesley121]

Depending on what meter is installed, allows different perceptible drops. 6mbar being the highest drop over 2mins. Anything after 2 mins doesn't count. Only time a drop, even if it's allowed on that particulat meter cannot be left is if the customer smells gas.

So say your allowed a 6mbar drop on the meter but find it's only dropping by 1 mbar over 2 mins. It's well within range but if the customer smells gas, it has to be sorted.

Also drops are only allowed with appliances attached. Therefore you are not allowed a drop full stop on any meter for pipework only.

The drops come from the likes of gas taps on appliances. As I was told, there's clever'er people than us that have worked out that a drop of whatever on a certain meter is perfectly safe. Who are we to argue.

 

[Nostrum]

8mb

 

[heatho87]

Ok thanks for the replys is it worth buying a digital tester or stay with the old fashed manometer?

 

[kirkgas]

8mb

this post aside, the rest are giving me palpitations:20:

heatho87 i appreciate you are only learning and therefore asking a question, but there are too many variables to answer you without confusing you, have a look in your training notes for a table of permissable drops depending on pipe size and/or a specific meter being fitted or not, if by chance you are using bpec notes you want Module 6

 

[Bernie2]

Some drops are accounted for by temperature variations, some by slight leaks that do not bring the localised gas content above NG LEL. But as been said, any smell of gas regardless of drop has to be investigated. I suppose they reckon that if you can smell gas the gas content must be approaching NG LEL.

 

[SafeGasInstall]

And most inportant NO SMELL OF GAS !!!
u could have 0.25 drop but if there is a smell of GAS
!!!
must MAKE SAFE !!!

 

[heatho87]

this post aside, the rest are giving me palpitations:20:

heatho87 i appreciate you are only learning and therefore asking a question, but there are too many variables to answer you without confusing you, have a look in your training notes for a table of permissable drops depending on pipe size and/or a specific meter being fitted or not, if by chance you are using bpec notes you want Module 6

Thanks I'll have a look, just nicer to talk to experienced people also!

 

[Nostrum]

And most inportant NO SMELL OF GAS !!!
u could have 0.25 drop but if there is a smell of GAS
!!!
must MAKE SAFE !!!

but thats classed as no discernible drop to confuse the situation more! (0.2 on a digital)

 

[heatho87]

So anything that happens after the 2 mins of testing doesn't count
?

 

[kirkgas]

Thanks I'll have a look, just nicer to talk to experienced people also!

i agree but if you ask "whats the permissable drop on an existing installation with an E6 and 35mm copper pipe" you will (should) get a specific answer from us, but there are too many variables on "what is allowed" but keep asking and keep learning

 

[Nostrum]

You have to think about it logically, if you have no movvement for 2 mins then it drops 1 mb in the next, something is wrong, a leak should have a steady rate of drop.

The test time (2 mins after 1 min temperature stabilisation) and the pressure drop allowed depending on meter (and therefore volume) gives an indication of the amount of gas allowed to pass in a given time. 2 mb over 30 mins would obviously be a completely different rate to 2mb over 10 seconds when you look at the amount of gas that could escape in say a 24hr period.

 

[Simon F]

assuming you have already tested for let by
then temperature stabilisation
then yes the test is 2 minutes
but as said so many variables for different size pipes and different meters as to allowable drop,
but off course there is no pressure loss allowed on pipe work only on existing appliances

 

[kirkgas]

So anything that happens after the 2 mins of testing doesn't count
?

thats it, the test criteria is 2 minutes so i have never noticed what happens after that, as soon as it hits 2 minutes the guage is off, and whatever happened by then is recorded or dealt with, i have assessed a few guys who say they always test for longer but thats actually down to their lack of confidence in their own ability, gas is only at 20mb so it scares me they dont trust their pipe joints we fit plumbing at 6 bar without any prob so we shouldnt be getting leaks at 20mb

 

[cannon]

New pipework you are not allowed no drop (tolerance) existing pipe work you are allowed 4mb over 2 mins( providing diameter of pipe work does not excede 0.35 then you would have to test as up1a not 1b) not 0.4 providing their is no smell reported based on a u 6 metre, the e series meters you are allowed 8 mb .Thus if you did install a section of new pipe work it would be prudent to treat the whole installation as new pipe work and no leakage allowances allowed ,if it was a commercial installation you could splay off new section and hydraulic test or pressurised with air or nitrogen but you would not do this on a domestic senerio because you are only dealing with small volumes. yes you are right allowances were given to equipment connected to gas train.cookers rely on gas cock grease taper jet spring and knitting plate to seal gas tap into female housing ,you can get passing through multi functional valves when you turn boiler off to do a soundness test AR untill you no better, gas fire valves can pass, gas never no smell because it drawn up through the chimney. worst senerio very common some dick head installed compression fitting under floor boards and it is weepping ,or very old installations were they have used fairy liquid as a leak detector corrosion in evidence so and so on ! So to realiterate you are allowed 4mb permmisable leakage rate over 2 mins not 0.4 providing let by test ok ! and if you extended existing pipework with new treat the whole installation as a new install and no permmisable leak rate allowed hope this may help

 

[heatho87]

thats it, the test criteria is 2 minutes so i have never noticed what happens after that, as soon as it hits 2 minutes the guage is off, and whatever happened by then is recorded or dealt with, i have assessed a few guys who say they always test for longer but thats actually down to their lack of confidence in their own ability, gas is only at 20mb so it scares me they dont trust their pipe joints we fit plumbing at 6 bar without any prob so we shouldnt be getting leaks at 20mb

Thats realy cleared it up for me thanks after 2 mins the test is over I just find myself doing it for longer but I shouldnt your right, maybe just doubting myself

 

[kirkgas]

Thats realy cleared it up for me thanks after 2 mins the test is over I just find myself doing it for longer but I shouldnt your right, maybe just doubting myself

no prob

 

[heatho87]

New pipework you are not allowed no drop (tolerance) existing pipe work you are allowed 4mb over 2 mins( providing diameter of pipe work does not excede 0.35 then you would have to test as up1a not 1b) not 0.4 providing their is no smell reported based on a u 6 metre, the e series meters you are allowed 8 mb .Thus if you did install a section of new pipe work it would be prudent to treat the whole installation as new pipe work and no leakage allowances allowed ,if it was a commercial installation you could splay off new section and hydraulic test or pressurised with air or nitrogen but you would not do this on a domestic senerio because you are only dealing with small volumes. yes you are right allowances were given to equipment connected to gas train.cookers rely on gas cock grease taper jet spring and knitting plate to seal gas tap into female housing ,you can get passing through multi functional valves when you turn boiler off to do a soundness test AR untill you no better, gas fire valves can pass, gas never no smell because it drawn up through the chimney. worst senerio very common some dick head installed compression fitting under floor boards and it is weepping ,or very old installations were they have used fairy liquid as a leak detector corrosion in evidence so and so on ! So to realiterate you are allowed 4mb permmisable leakage rate over 2 mins not 0.4 providing let by test ok ! and if you extended existing pipework with new treat the whole installation as a new install and no permmisable leak rate allowed hope this may help

Thanks very detailed and helpful, I just find the u gauge while testing is a pain that's why I want to no wether it's worth getting a digital one also easier and quicker I'm I correct

 

[Nostrum]

Personally, rather than test the whole installation as new when adding to it I always test twice. Once before you do anything at all, then once you have completed the work. Otherwise you end up taking on other peoples problems, and the customers always say ' it was ok before you touched it' and your thinking ' how the heck would you know love, and get the kettle on!

 

[kirkgas]

New pipework you are not allowed no drop (tolerance) existing pipe work you are allowed 4mb over 2 mins( providing diameter of pipe work does not excede 0.35 then you would have to test as up1a not 1b) not 0.4 providing their is no smell reported based on a u 6 metre, the e series meters you are allowed 8 mb .Thus if you did install a section of new pipe work it would be prudent to treat the whole installation as new pipe work and no leakage allowances allowed ,if it was a commercial installation you could splay off new section and hydraulic test or pressurised with air or nitrogen but you would not do this on a domestic senerio because you are only dealing with small volumes. yes you are right allowances were given to equipment connected to gas train.cookers rely on gas cock grease taper jet spring and knitting plate to seal gas tap into female housing ,you can get passing through multi functional valves when you turn boiler off to do a soundness test AR untill you no better, gas fire valves can pass, gas never no smell because it drawn up through the chimney. worst senerio very common some dick head installed compression fitting under floor boards and it is weepping ,or very old installations were they have used fairy liquid as a leak detector corrosion in evidence so and so on ! So to realiterate you are allowed 4mb permmisable leakage rate over 2 mins not 0.4 providing let by test ok ! and if you extended existing pipework with new treat the whole installation as a new install and no permmisable leak rate allowed hope this may help

i agree with everything you say here except the bit about adding to an existing install and treating it all as new with no drop, unless im misunderstanding what you are describing, if i test an existing install with appliances and get a 1mb drop i would tee in my new section and retest when done expecting to get no more than 1mb proving (as i need to ) that my new section is gas tight.

 

[tamz]

Ok thanks for the replys is it worth buying a digital tester or stay with the old fashed manometer?

A manometer will never lie and never needs calibrating.

 

[Doodlebug]

A manometer will never lie and never needs calibrating.

Im with tamz on this, get yourself a manometer mate.

 

[SafeGasInstall]

I have useda digital ...... Would not recomend them as when there is change of the outside air temperatureit gives wrong reading , i am speaking of Anton digital ma ometer not the analiser !

 

[SilentMike]

Another point is that these drops you are allowed are the same amount of gas just show up different due to the size of the meter and pipe work